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. 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 comma-separated list of requested sample formats.
139 A comma-separated list of requested sample rates.
141 @item channel_layouts
142 A comma-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 Show a line containing various information for each input audio frame.
198 The input audio is not modified.
200 The shown line contains a sequence of key/value pairs of the form
201 @var{key}:@var{value}.
203 A description of each shown parameter follows:
207 sequential number of the input frame, starting from 0
210 Presentation timestamp of the input frame, in time base units; the time base
211 depends on the filter input pad, and is usually 1/@var{sample_rate}.
214 presentation timestamp of the input frame in seconds
223 sample rate for the audio frame
226 number of samples (per channel) in the frame
229 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
230 the data is treated as if all the planes were concatenated.
232 @item plane_checksums
233 A list of Adler-32 checksums for each data plane.
238 Split input audio into several identical outputs.
240 The filter accepts a single parameter which specifies the number of outputs. If
241 unspecified, it defaults to 2.
245 avconv -i INPUT -filter_complex asplit=5 OUTPUT
247 will create 5 copies of the input audio.
250 Synchronize audio data with timestamps by squeezing/stretching it and/or
251 dropping samples/adding silence when needed.
253 The filter accepts the following named parameters:
257 Enable stretching/squeezing the data to make it match the timestamps. Disabled
258 by default. When disabled, time gaps are covered with silence.
261 Minimum difference between timestamps and audio data (in seconds) to trigger
262 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
263 this filter, try setting this parameter to 0.
266 Maximum compensation in samples per second. Relevant only with compensate=1.
270 Assume the first pts should be this value. The time base is 1 / sample rate.
271 This allows for padding/trimming at the start of stream. By default, no
272 assumption is made about the first frame's expected pts, so no padding or
273 trimming is done. For example, this could be set to 0 to pad the beginning with
274 silence if an audio stream starts after the video stream or to trim any samples
275 with a negative pts due to encoder delay.
279 @section channelsplit
280 Split each channel in input audio stream into a separate output stream.
282 This filter accepts the following named parameters:
285 Channel layout of the input stream. Default is "stereo".
288 For example, assuming a stereo input MP3 file
290 avconv -i in.mp3 -filter_complex channelsplit out.mkv
292 will create an output Matroska file with two audio streams, one containing only
293 the left channel and the other the right channel.
295 To split a 5.1 WAV file into per-channel files
297 avconv -i in.wav -filter_complex
298 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
299 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
300 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
305 Remap input channels to new locations.
307 This filter accepts the following named parameters:
310 Channel layout of the output stream.
313 Map channels from input to output. The argument is a comma-separated list of
314 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
315 @var{in_channel} form. @var{in_channel} can be either the name of the input
316 channel (e.g. FL for front left) or its index in the input channel layout.
317 @var{out_channel} is the name of the output channel or its index in the output
318 channel layout. If @var{out_channel} is not given then it is implicitly an
319 index, starting with zero and increasing by one for each mapping.
322 If no mapping is present, the filter will implicitly map input channels to
323 output channels preserving index.
325 For example, assuming a 5.1+downmix input MOV file
327 avconv -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
329 will create an output WAV file tagged as stereo from the downmix channels of
332 To fix a 5.1 WAV improperly encoded in AAC's native channel order
334 avconv -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
338 Join multiple input streams into one multi-channel stream.
340 The filter accepts the following named parameters:
344 Number of input streams. Defaults to 2.
347 Desired output channel layout. Defaults to stereo.
350 Map channels from inputs to output. The argument is a comma-separated list of
351 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
352 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
353 can be either the name of the input channel (e.g. FL for front left) or its
354 index in the specified input stream. @var{out_channel} is the name of the output
358 The filter will attempt to guess the mappings when those are not specified
359 explicitly. It does so by first trying to find an unused matching input channel
360 and if that fails it picks the first unused input channel.
362 E.g. to join 3 inputs (with properly set channel layouts)
364 avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
367 To build a 5.1 output from 6 single-channel streams:
369 avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
370 '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'
375 Convert the audio sample format, sample rate and channel layout. This filter is
376 not meant to be used directly, it is inserted automatically by libavfilter
377 whenever conversion is needed. Use the @var{aformat} filter to force a specific
382 Adjust the input audio volume.
384 The filter accepts the following named parameters:
388 Expresses how the audio volume will be increased or decreased.
390 Output values are clipped to the maximum value.
392 The output audio volume is given by the relation:
394 @var{output_volume} = @var{volume} * @var{input_volume}
397 Default value for @var{volume} is 1.0.
400 Mathematical precision.
402 This determines which input sample formats will be allowed, which affects the
403 precision of the volume scaling.
407 8-bit fixed-point; limits input sample format to U8, S16, and S32.
409 32-bit floating-point; limits input sample format to FLT. (default)
411 64-bit floating-point; limits input sample format to DBL.
419 Halve the input audio volume:
423 volume=volume=-6.0206dB
427 Increase input audio power by 6 decibels using fixed-point precision:
429 volume=volume=6dB:precision=fixed
433 @c man end AUDIO FILTERS
435 @chapter Audio Sources
436 @c man begin AUDIO SOURCES
438 Below is a description of the currently available audio sources.
442 Null audio source, never return audio frames. It is mainly useful as a
443 template and to be employed in analysis / debugging tools.
445 It accepts as optional parameter a string of the form
446 @var{sample_rate}:@var{channel_layout}.
448 @var{sample_rate} specify the sample rate, and defaults to 44100.
450 @var{channel_layout} specify the channel layout, and can be either an
451 integer or a string representing a channel layout. The default value
452 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
454 Check the channel_layout_map definition in
455 @file{libavutil/channel_layout.c} for the mapping between strings and
456 channel layout values.
458 Follow some examples:
460 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
468 Buffer audio frames, and make them available to the filter chain.
470 This source is not intended to be part of user-supplied graph descriptions but
471 for insertion by calling programs through the interface defined in
472 @file{libavfilter/buffersrc.h}.
474 It accepts the following named parameters:
478 Timebase which will be used for timestamps of submitted frames. It must be
479 either a floating-point number or in @var{numerator}/@var{denominator} form.
485 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
488 Channel layout of the audio data, in the form that can be accepted by
489 @code{av_get_channel_layout()}.
492 All the parameters need to be explicitly defined.
494 @c man end AUDIO SOURCES
497 @c man begin AUDIO SINKS
499 Below is a description of the currently available audio sinks.
503 Null audio sink, do absolutely nothing with the input audio. It is
504 mainly useful as a template and to be employed in analysis / debugging
508 This sink is intended for programmatic use. Frames that arrive on this sink can
509 be retrieved by the calling program using the interface defined in
510 @file{libavfilter/buffersink.h}.
512 This filter accepts no parameters.
514 @c man end AUDIO SINKS
516 @chapter Video Filters
517 @c man begin VIDEO FILTERS
519 When you configure your Libav build, you can disable any of the
520 existing filters using --disable-filters.
521 The configure output will show the video filters included in your
524 Below is a description of the currently available video filters.
528 Detect frames that are (almost) completely black. Can be useful to
529 detect chapter transitions or commercials. Output lines consist of
530 the frame number of the detected frame, the percentage of blackness,
531 the position in the file if known or -1 and the timestamp in seconds.
533 In order to display the output lines, you need to set the loglevel at
534 least to the AV_LOG_INFO value.
536 The filter accepts the syntax:
538 blackframe[=@var{amount}:[@var{threshold}]]
541 @var{amount} is the percentage of the pixels that have to be below the
542 threshold, and defaults to 98.
544 @var{threshold} is the threshold below which a pixel value is
545 considered black, and defaults to 32.
549 Apply boxblur algorithm to the input video.
551 This filter accepts the parameters:
552 @var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
554 Chroma and alpha parameters are optional, if not specified they default
555 to the corresponding values set for @var{luma_radius} and
558 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
559 the radius in pixels of the box used for blurring the corresponding
560 input plane. They are expressions, and can contain the following
564 the input width and height in pixels
567 the input chroma image width and height in pixels
570 horizontal and vertical chroma subsample values. For example for the
571 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
574 The radius must be a non-negative number, and must not be greater than
575 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
576 and of @code{min(cw,ch)/2} for the chroma planes.
578 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
579 how many times the boxblur filter is applied to the corresponding
582 Some examples follow:
587 Apply a boxblur filter with luma, chroma, and alpha radius
594 Set luma radius to 2, alpha and chroma radius to 0
600 Set luma and chroma radius to a fraction of the video dimension
602 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
609 Copy the input source unchanged to the output. Mainly useful for
614 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
616 The parameters are expressions containing the following constants:
620 the corresponding mathematical approximated values for e
621 (euler number), pi (greek PI), PHI (golden ratio)
624 the computed values for @var{x} and @var{y}. They are evaluated for
628 the input width and height
631 same as @var{in_w} and @var{in_h}
634 the output (cropped) width and height
637 same as @var{out_w} and @var{out_h}
640 the number of input frame, starting from 0
643 timestamp expressed in seconds, NAN if the input timestamp is unknown
647 The @var{out_w} and @var{out_h} parameters specify the expressions for
648 the width and height of the output (cropped) video. They are
649 evaluated just at the configuration of the filter.
651 The default value of @var{out_w} is "in_w", and the default value of
652 @var{out_h} is "in_h".
654 The expression for @var{out_w} may depend on the value of @var{out_h},
655 and the expression for @var{out_h} may depend on @var{out_w}, but they
656 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
657 evaluated after @var{out_w} and @var{out_h}.
659 The @var{x} and @var{y} parameters specify the expressions for the
660 position of the top-left corner of the output (non-cropped) area. They
661 are evaluated for each frame. If the evaluated value is not valid, it
662 is approximated to the nearest valid value.
664 The default value of @var{x} is "(in_w-out_w)/2", and the default
665 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
666 the center of the input image.
668 The expression for @var{x} may depend on @var{y}, and the expression
669 for @var{y} may depend on @var{x}.
671 Follow some examples:
673 # crop the central input area with size 100x100
676 # crop the central input area with size 2/3 of the input video
677 "crop=2/3*in_w:2/3*in_h"
679 # crop the input video central square
682 # delimit the rectangle with the top-left corner placed at position
683 # 100:100 and the right-bottom corner corresponding to the right-bottom
684 # corner of the input image.
685 crop=in_w-100:in_h-100:100:100
687 # crop 10 pixels from the left and right borders, and 20 pixels from
688 # the top and bottom borders
689 "crop=in_w-2*10:in_h-2*20"
691 # keep only the bottom right quarter of the input image
692 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
694 # crop height for getting Greek harmony
695 "crop=in_w:1/PHI*in_w"
698 "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)"
700 # erratic camera effect depending on timestamp
701 "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)"
703 # set x depending on the value of y
704 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
709 Auto-detect crop size.
711 Calculate necessary cropping parameters and prints the recommended
712 parameters through the logging system. The detected dimensions
713 correspond to the non-black area of the input video.
715 It accepts the syntax:
717 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
723 Threshold, which can be optionally specified from nothing (0) to
724 everything (255), defaults to 24.
727 Value which the width/height should be divisible by, defaults to
728 16. The offset is automatically adjusted to center the video. Use 2 to
729 get only even dimensions (needed for 4:2:2 video). 16 is best when
730 encoding to most video codecs.
733 Counter that determines after how many frames cropdetect will reset
734 the previously detected largest video area and start over to detect
735 the current optimal crop area. Defaults to 0.
737 This can be useful when channel logos distort the video area. 0
738 indicates never reset and return the largest area encountered during
744 Suppress a TV station logo by a simple interpolation of the surrounding
745 pixels. Just set a rectangle covering the logo and watch it disappear
746 (and sometimes something even uglier appear - your mileage may vary).
748 The filter accepts parameters as a string of the form
749 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
750 @var{key}=@var{value} pairs, separated by ":".
752 The description of the accepted parameters follows.
757 Specify the top left corner coordinates of the logo. They must be
761 Specify the width and height of the logo to clear. They must be
765 Specify the thickness of the fuzzy edge of the rectangle (added to
766 @var{w} and @var{h}). The default value is 4.
769 When set to 1, a green rectangle is drawn on the screen to simplify
770 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
771 @var{band} is set to 4. The default value is 0.
775 Some examples follow.
780 Set a rectangle covering the area with top left corner coordinates 0,0
781 and size 100x77, setting a band of size 10:
787 As the previous example, but use named options:
789 delogo=x=0:y=0:w=100:h=77:band=10
796 Draw a colored box on the input image.
798 It accepts the syntax:
800 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
806 Specify the top left corner coordinates of the box. Default to 0.
809 Specify the width and height of the box, if 0 they are interpreted as
810 the input width and height. Default to 0.
813 Specify the color of the box to write, it can be the name of a color
814 (case insensitive match) or a 0xRRGGBB[AA] sequence.
817 Follow some examples:
819 # draw a black box around the edge of the input image
822 # draw a box with color red and an opacity of 50%
823 drawbox=10:20:200:60:red@@0.5"
828 Draw text string or text from specified file on top of video using the
831 To enable compilation of this filter you need to configure Libav with
832 @code{--enable-libfreetype}.
834 The filter also recognizes strftime() sequences in the provided text
835 and expands them accordingly. Check the documentation of strftime().
837 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
840 The description of the accepted parameters follows.
845 The font file to be used for drawing text. Path must be included.
846 This parameter is mandatory.
849 The text string to be drawn. The text must be a sequence of UTF-8
851 This parameter is mandatory if no file is specified with the parameter
855 A text file containing text to be drawn. The text must be a sequence
856 of UTF-8 encoded characters.
858 This parameter is mandatory if no text string is specified with the
859 parameter @var{text}.
861 If both text and textfile are specified, an error is thrown.
864 The offsets where text will be drawn within the video frame.
865 Relative to the top/left border of the output image.
866 They accept expressions similar to the @ref{overlay} filter:
870 the computed values for @var{x} and @var{y}. They are evaluated for
874 main input width and height
877 same as @var{main_w} and @var{main_h}
880 rendered text width and height
883 same as @var{text_w} and @var{text_h}
886 the number of frames processed, starting from 0
889 timestamp expressed in seconds, NAN if the input timestamp is unknown
893 The default value of @var{x} and @var{y} is 0.
896 The font size to be used for drawing text.
897 The default value of @var{fontsize} is 16.
900 The color to be used for drawing fonts.
901 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
902 (e.g. "0xff000033"), possibly followed by an alpha specifier.
903 The default value of @var{fontcolor} is "black".
906 The color to be used for drawing box around text.
907 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
908 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
909 The default value of @var{boxcolor} is "white".
912 Used to draw a box around text using background color.
913 Value should be either 1 (enable) or 0 (disable).
914 The default value of @var{box} is 0.
916 @item shadowx, shadowy
917 The x and y offsets for the text shadow position with respect to the
918 position of the text. They can be either positive or negative
919 values. Default value for both is "0".
922 The color to be used for drawing a shadow behind the drawn text. It
923 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
924 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
925 The default value of @var{shadowcolor} is "black".
928 Flags to be used for loading the fonts.
930 The flags map the corresponding flags supported by libfreetype, and are
931 a combination of the following values:
938 @item vertical_layout
942 @item ignore_global_advance_width
944 @item ignore_transform
951 Default value is "render".
953 For more information consult the documentation for the FT_LOAD_*
957 The size in number of spaces to use for rendering the tab.
961 If true, check and fix text coords to avoid clipping.
964 For example the command:
966 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
969 will draw "Test Text" with font FreeSerif, using the default values
970 for the optional parameters.
974 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
975 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
978 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
979 and y=50 (counting from the top-left corner of the screen), text is
980 yellow with a red box around it. Both the text and the box have an
983 Note that the double quotes are not necessary if spaces are not used
984 within the parameter list.
986 For more information about libfreetype, check:
987 @url{http://www.freetype.org/}.
991 Apply fade-in/out effect to input video.
993 It accepts the parameters:
994 @var{type}:@var{start_frame}:@var{nb_frames}
996 @var{type} specifies if the effect type, can be either "in" for
997 fade-in, or "out" for a fade-out effect.
999 @var{start_frame} specifies the number of the start frame for starting
1000 to apply the fade effect.
1002 @var{nb_frames} specifies the number of frames for which the fade
1003 effect has to last. At the end of the fade-in effect the output video
1004 will have the same intensity as the input video, at the end of the
1005 fade-out transition the output video will be completely black.
1007 A few usage examples follow, usable too as test scenarios.
1009 # fade in first 30 frames of video
1012 # fade out last 45 frames of a 200-frame video
1015 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1016 fade=in:0:25, fade=out:975:25
1018 # make first 5 frames black, then fade in from frame 5-24
1024 Transform the field order of the input video.
1026 It accepts one parameter which specifies the required field order that
1027 the input interlaced video will be transformed to. The parameter can
1028 assume one of the following values:
1032 output bottom field first
1034 output top field first
1037 Default value is "tff".
1039 Transformation is achieved by shifting the picture content up or down
1040 by one line, and filling the remaining line with appropriate picture content.
1041 This method is consistent with most broadcast field order converters.
1043 If the input video is not flagged as being interlaced, or it is already
1044 flagged as being of the required output field order then this filter does
1045 not alter the incoming video.
1047 This filter is very useful when converting to or from PAL DV material,
1048 which is bottom field first.
1052 ./avconv -i in.vob -vf "fieldorder=bff" out.dv
1057 Buffer input images and send them when they are requested.
1059 This filter is mainly useful when auto-inserted by the libavfilter
1062 The filter does not take parameters.
1066 Convert the input video to one of the specified pixel formats.
1067 Libavfilter will try to pick one that is supported for the input to
1070 The filter accepts a list of pixel format names, separated by ":",
1071 for example "yuv420p:monow:rgb24".
1073 Some examples follow:
1075 # convert the input video to the format "yuv420p"
1078 # convert the input video to any of the formats in the list
1079 format=yuv420p:yuv444p:yuv410p
1084 Convert the video to specified constant framerate by duplicating or dropping
1085 frames as necessary.
1087 This filter accepts the following named parameters:
1091 Desired output framerate.
1098 Apply a frei0r effect to the input video.
1100 To enable compilation of this filter you need to install the frei0r
1101 header and configure Libav with --enable-frei0r.
1103 The filter supports the syntax:
1105 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1108 @var{filter_name} is the name to the frei0r effect to load. If the
1109 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1110 is searched in each one of the directories specified by the colon
1111 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1112 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1113 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1115 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1116 for the frei0r effect.
1118 A frei0r effect parameter can be a boolean (whose values are specified
1119 with "y" and "n"), a double, a color (specified by the syntax
1120 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1121 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1122 description), a position (specified by the syntax @var{X}/@var{Y},
1123 @var{X} and @var{Y} being float numbers) and a string.
1125 The number and kind of parameters depend on the loaded effect. If an
1126 effect parameter is not specified the default value is set.
1128 Some examples follow:
1130 # apply the distort0r effect, set the first two double parameters
1131 frei0r=distort0r:0.5:0.01
1133 # apply the colordistance effect, takes a color as first parameter
1134 frei0r=colordistance:0.2/0.3/0.4
1135 frei0r=colordistance:violet
1136 frei0r=colordistance:0x112233
1138 # apply the perspective effect, specify the top left and top right
1140 frei0r=perspective:0.2/0.2:0.8/0.2
1143 For more information see:
1144 @url{http://piksel.org/frei0r}
1148 Fix the banding artifacts that are sometimes introduced into nearly flat
1149 regions by truncation to 8bit colordepth.
1150 Interpolate the gradients that should go where the bands are, and
1153 This filter is designed for playback only. Do not use it prior to
1154 lossy compression, because compression tends to lose the dither and
1155 bring back the bands.
1157 The filter takes two optional parameters, separated by ':':
1158 @var{strength}:@var{radius}
1160 @var{strength} is the maximum amount by which the filter will change
1161 any one pixel. Also the threshold for detecting nearly flat
1162 regions. Acceptable values range from .51 to 64, default value is
1163 1.2, out-of-range values will be clipped to the valid range.
1165 @var{radius} is the neighborhood to fit the gradient to. A larger
1166 radius makes for smoother gradients, but also prevents the filter from
1167 modifying the pixels near detailed regions. Acceptable values are
1168 8-32, default value is 16, out-of-range values will be clipped to the
1172 # default parameters
1181 Flip the input video horizontally.
1183 For example to horizontally flip the input video with @command{avconv}:
1185 avconv -i in.avi -vf "hflip" out.avi
1190 High precision/quality 3d denoise filter. This filter aims to reduce
1191 image noise producing smooth images and making still images really
1192 still. It should enhance compressibility.
1194 It accepts the following optional parameters:
1195 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1199 a non-negative float number which specifies spatial luma strength,
1202 @item chroma_spatial
1203 a non-negative float number which specifies spatial chroma strength,
1204 defaults to 3.0*@var{luma_spatial}/4.0
1207 a float number which specifies luma temporal strength, defaults to
1208 6.0*@var{luma_spatial}/4.0
1211 a float number which specifies chroma temporal strength, defaults to
1212 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1215 @section lut, lutrgb, lutyuv
1217 Compute a look-up table for binding each pixel component input value
1218 to an output value, and apply it to input video.
1220 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1221 to an RGB input video.
1223 These filters accept in input a ":"-separated list of options, which
1224 specify the expressions used for computing the lookup table for the
1225 corresponding pixel component values.
1227 The @var{lut} filter requires either YUV or RGB pixel formats in
1228 input, and accepts the options:
1230 @item @var{c0} (first pixel component)
1231 @item @var{c1} (second pixel component)
1232 @item @var{c2} (third pixel component)
1233 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
1236 The exact component associated to each option depends on the format in
1239 The @var{lutrgb} filter requires RGB pixel formats in input, and
1240 accepts the options:
1242 @item @var{r} (red component)
1243 @item @var{g} (green component)
1244 @item @var{b} (blue component)
1245 @item @var{a} (alpha component)
1248 The @var{lutyuv} filter requires YUV pixel formats in input, and
1249 accepts the options:
1251 @item @var{y} (Y/luminance component)
1252 @item @var{u} (U/Cb component)
1253 @item @var{v} (V/Cr component)
1254 @item @var{a} (alpha component)
1257 The expressions can contain the following constants and functions:
1261 the corresponding mathematical approximated values for e
1262 (euler number), pi (greek PI), PHI (golden ratio)
1265 the input width and height
1268 input value for the pixel component
1271 the input value clipped in the @var{minval}-@var{maxval} range
1274 maximum value for the pixel component
1277 minimum value for the pixel component
1280 the negated value for the pixel component value clipped in the
1281 @var{minval}-@var{maxval} range , it corresponds to the expression
1282 "maxval-clipval+minval"
1285 the computed value in @var{val} clipped in the
1286 @var{minval}-@var{maxval} range
1288 @item gammaval(gamma)
1289 the computed gamma correction value of the pixel component value
1290 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1292 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1296 All expressions default to "val".
1298 Some examples follow:
1300 # negate input video
1301 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1302 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1304 # the above is the same as
1305 lutrgb="r=negval:g=negval:b=negval"
1306 lutyuv="y=negval:u=negval:v=negval"
1311 # remove chroma components, turns the video into a graytone image
1312 lutyuv="u=128:v=128"
1314 # apply a luma burning effect
1317 # remove green and blue components
1320 # set a constant alpha channel value on input
1321 format=rgba,lutrgb=a="maxval-minval/2"
1323 # correct luminance gamma by a 0.5 factor
1324 lutyuv=y=gammaval(0.5)
1331 This filter accepts an integer in input, if non-zero it negates the
1332 alpha component (if available). The default value in input is 0.
1336 Force libavfilter not to use any of the specified pixel formats for the
1337 input to the next filter.
1339 The filter accepts a list of pixel format names, separated by ":",
1340 for example "yuv420p:monow:rgb24".
1342 Some examples follow:
1344 # force libavfilter to use a format different from "yuv420p" for the
1345 # input to the vflip filter
1346 noformat=yuv420p,vflip
1348 # convert the input video to any of the formats not contained in the list
1349 noformat=yuv420p:yuv444p:yuv410p
1354 Pass the video source unchanged to the output.
1358 Apply video transform using libopencv.
1360 To enable this filter install libopencv library and headers and
1361 configure Libav with --enable-libopencv.
1363 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1365 @var{filter_name} is the name of the libopencv filter to apply.
1367 @var{filter_params} specifies the parameters to pass to the libopencv
1368 filter. If not specified the default values are assumed.
1370 Refer to the official libopencv documentation for more precise
1372 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1374 Follows the list of supported libopencv filters.
1379 Dilate an image by using a specific structuring element.
1380 This filter corresponds to the libopencv function @code{cvDilate}.
1382 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1384 @var{struct_el} represents a structuring element, and has the syntax:
1385 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1387 @var{cols} and @var{rows} represent the number of columns and rows of
1388 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1389 point, and @var{shape} the shape for the structuring element, and
1390 can be one of the values "rect", "cross", "ellipse", "custom".
1392 If the value for @var{shape} is "custom", it must be followed by a
1393 string of the form "=@var{filename}". The file with name
1394 @var{filename} is assumed to represent a binary image, with each
1395 printable character corresponding to a bright pixel. When a custom
1396 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1397 or columns and rows of the read file are assumed instead.
1399 The default value for @var{struct_el} is "3x3+0x0/rect".
1401 @var{nb_iterations} specifies the number of times the transform is
1402 applied to the image, and defaults to 1.
1404 Follow some example:
1406 # use the default values
1409 # dilate using a structuring element with a 5x5 cross, iterate two times
1410 ocv=dilate=5x5+2x2/cross:2
1412 # read the shape from the file diamond.shape, iterate two times
1413 # the file diamond.shape may contain a pattern of characters like this:
1419 # the specified cols and rows are ignored (but not the anchor point coordinates)
1420 ocv=0x0+2x2/custom=diamond.shape:2
1425 Erode an image by using a specific structuring element.
1426 This filter corresponds to the libopencv function @code{cvErode}.
1428 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1429 with the same syntax and semantics as the @ref{dilate} filter.
1433 Smooth the input video.
1435 The filter takes the following parameters:
1436 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1438 @var{type} is the type of smooth filter to apply, and can be one of
1439 the following values: "blur", "blur_no_scale", "median", "gaussian",
1440 "bilateral". The default value is "gaussian".
1442 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1443 parameters whose meanings depend on smooth type. @var{param1} and
1444 @var{param2} accept integer positive values or 0, @var{param3} and
1445 @var{param4} accept float values.
1447 The default value for @var{param1} is 3, the default value for the
1448 other parameters is 0.
1450 These parameters correspond to the parameters assigned to the
1451 libopencv function @code{cvSmooth}.
1456 Overlay one video on top of another.
1458 It takes two inputs and one output, the first input is the "main"
1459 video on which the second input is overlayed.
1461 It accepts the parameters: @var{x}:@var{y}.
1463 @var{x} is the x coordinate of the overlayed video on the main video,
1464 @var{y} is the y coordinate. The parameters are expressions containing
1465 the following parameters:
1468 @item main_w, main_h
1469 main input width and height
1472 same as @var{main_w} and @var{main_h}
1474 @item overlay_w, overlay_h
1475 overlay input width and height
1478 same as @var{overlay_w} and @var{overlay_h}
1481 Be aware that frames are taken from each input video in timestamp
1482 order, hence, if their initial timestamps differ, it is a a good idea
1483 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1484 have them begin in the same zero timestamp, as it does the example for
1485 the @var{movie} filter.
1487 Follow some examples:
1489 # draw the overlay at 10 pixels from the bottom right
1490 # corner of the main video.
1491 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1493 # insert a transparent PNG logo in the bottom left corner of the input
1494 avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
1496 # insert 2 different transparent PNG logos (second logo on bottom
1498 avconv -i input -i logo1 -i logo2 -filter_complex
1499 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
1501 # add a transparent color layer on top of the main video,
1502 # WxH specifies the size of the main input to the overlay filter
1503 color=red@.3:WxH [over]; [in][over] overlay [out]
1506 You can chain together more overlays but the efficiency of such
1507 approach is yet to be tested.
1511 Add paddings to the input image, and places the original input at the
1512 given coordinates @var{x}, @var{y}.
1514 It accepts the following parameters:
1515 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1517 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1518 expressions containing the following constants:
1522 the corresponding mathematical approximated values for e
1523 (euler number), pi (greek PI), phi (golden ratio)
1526 the input video width and height
1529 same as @var{in_w} and @var{in_h}
1532 the output width and height, that is the size of the padded area as
1533 specified by the @var{width} and @var{height} expressions
1536 same as @var{out_w} and @var{out_h}
1539 x and y offsets as specified by the @var{x} and @var{y}
1540 expressions, or NAN if not yet specified
1543 input display aspect ratio, same as @var{iw} / @var{ih}
1546 horizontal and vertical chroma subsample values. For example for the
1547 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1550 Follows the description of the accepted parameters.
1555 Specify the size of the output image with the paddings added. If the
1556 value for @var{width} or @var{height} is 0, the corresponding input size
1557 is used for the output.
1559 The @var{width} expression can reference the value set by the
1560 @var{height} expression, and vice versa.
1562 The default value of @var{width} and @var{height} is 0.
1566 Specify the offsets where to place the input image in the padded area
1567 with respect to the top/left border of the output image.
1569 The @var{x} expression can reference the value set by the @var{y}
1570 expression, and vice versa.
1572 The default value of @var{x} and @var{y} is 0.
1576 Specify the color of the padded area, it can be the name of a color
1577 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1579 The default value of @var{color} is "black".
1583 Some examples follow:
1586 # Add paddings with color "violet" to the input video. Output video
1587 # size is 640x480, the top-left corner of the input video is placed at
1589 pad=640:480:0:40:violet
1591 # pad the input to get an output with dimensions increased bt 3/2,
1592 # and put the input video at the center of the padded area
1593 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1595 # pad the input to get a squared output with size equal to the maximum
1596 # value between the input width and height, and put the input video at
1597 # the center of the padded area
1598 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1600 # pad the input to get a final w/h ratio of 16:9
1601 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1603 # double output size and put the input video in the bottom-right
1604 # corner of the output padded area
1605 pad="2*iw:2*ih:ow-iw:oh-ih"
1608 @section pixdesctest
1610 Pixel format descriptor test filter, mainly useful for internal
1611 testing. The output video should be equal to the input video.
1615 format=monow, pixdesctest
1618 can be used to test the monowhite pixel format descriptor definition.
1622 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1624 The parameters @var{width} and @var{height} are expressions containing
1625 the following constants:
1629 the corresponding mathematical approximated values for e
1630 (euler number), pi (greek PI), phi (golden ratio)
1633 the input width and height
1636 same as @var{in_w} and @var{in_h}
1639 the output (cropped) width and height
1642 same as @var{out_w} and @var{out_h}
1645 input display aspect ratio, same as @var{iw} / @var{ih}
1648 input sample aspect ratio
1651 horizontal and vertical chroma subsample values. For example for the
1652 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1655 If the input image format is different from the format requested by
1656 the next filter, the scale filter will convert the input to the
1659 If the value for @var{width} or @var{height} is 0, the respective input
1660 size is used for the output.
1662 If the value for @var{width} or @var{height} is -1, the scale filter will
1663 use, for the respective output size, a value that maintains the aspect
1664 ratio of the input image.
1666 The default value of @var{width} and @var{height} is 0.
1668 Some examples follow:
1670 # scale the input video to a size of 200x100.
1673 # scale the input to 2x
1675 # the above is the same as
1678 # scale the input to half size
1681 # increase the width, and set the height to the same size
1684 # seek for Greek harmony
1688 # increase the height, and set the width to 3/2 of the height
1691 # increase the size, but make the size a multiple of the chroma
1692 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1694 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1695 scale='min(500\, iw*3/2):-1'
1699 Select frames to pass in output.
1701 It accepts in input an expression, which is evaluated for each input
1702 frame. If the expression is evaluated to a non-zero value, the frame
1703 is selected and passed to the output, otherwise it is discarded.
1705 The expression can contain the following constants:
1718 the sequential number of the filtered frame, starting from 0
1721 the sequential number of the selected frame, starting from 0
1723 @item prev_selected_n
1724 the sequential number of the last selected frame, NAN if undefined
1727 timebase of the input timestamps
1730 the PTS (Presentation TimeStamp) of the filtered video frame,
1731 expressed in @var{TB} units, NAN if undefined
1734 the PTS (Presentation TimeStamp) of the filtered video frame,
1735 expressed in seconds, NAN if undefined
1738 the PTS of the previously filtered video frame, NAN if undefined
1740 @item prev_selected_pts
1741 the PTS of the last previously filtered video frame, NAN if undefined
1743 @item prev_selected_t
1744 the PTS of the last previously selected video frame, NAN if undefined
1747 the PTS of the first video frame in the video, NAN if undefined
1750 the time of the first video frame in the video, NAN if undefined
1753 the type of the filtered frame, can assume one of the following
1765 @item interlace_type
1766 the frame interlace type, can assume one of the following values:
1769 the frame is progressive (not interlaced)
1771 the frame is top-field-first
1773 the frame is bottom-field-first
1777 1 if the filtered frame is a key-frame, 0 otherwise
1781 The default value of the select expression is "1".
1783 Some examples follow:
1786 # select all frames in input
1789 # the above is the same as:
1795 # select only I-frames
1796 select='eq(pict_type\,I)'
1798 # select one frame every 100
1799 select='not(mod(n\,100))'
1801 # select only frames contained in the 10-20 time interval
1802 select='gte(t\,10)*lte(t\,20)'
1804 # select only I frames contained in the 10-20 time interval
1805 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1807 # select frames with a minimum distance of 10 seconds
1808 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1814 Set the Display Aspect Ratio for the filter output video.
1816 This is done by changing the specified Sample (aka Pixel) Aspect
1817 Ratio, according to the following equation:
1818 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1820 Keep in mind that this filter does not modify the pixel dimensions of
1821 the video frame. Also the display aspect ratio set by this filter may
1822 be changed by later filters in the filterchain, e.g. in case of
1823 scaling or if another "setdar" or a "setsar" filter is applied.
1825 The filter accepts a parameter string which represents the wanted
1826 display aspect ratio.
1827 The parameter can be a floating point number string, or an expression
1828 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1829 numerator and denominator of the aspect ratio.
1830 If the parameter is not specified, it is assumed the value "0:1".
1832 For example to change the display aspect ratio to 16:9, specify:
1835 # the above is equivalent to
1839 See also the @ref{setsar} filter documentation.
1843 Change the PTS (presentation timestamp) of the input video frames.
1845 Accept in input an expression evaluated through the eval API, which
1846 can contain the following constants:
1850 the presentation timestamp in input
1862 the count of the input frame, starting from 0.
1865 the PTS of the first video frame
1868 tell if the current frame is interlaced
1877 wallclock (RTC) time in microseconds
1880 wallclock (RTC) time at the start of the movie in microseconds
1884 Some examples follow:
1887 # start counting PTS from zero
1899 # fixed rate 25 fps with some jitter
1900 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1902 # generate timestamps from a "live source" and rebase onto the current timebase
1903 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
1909 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1911 Note that as a consequence of the application of this filter, the
1912 output display aspect ratio will change according to the following
1914 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1916 Keep in mind that the sample aspect ratio set by this filter may be
1917 changed by later filters in the filterchain, e.g. if another "setsar"
1918 or a "setdar" filter is applied.
1920 The filter accepts a parameter string which represents the wanted
1921 sample aspect ratio.
1922 The parameter can be a floating point number string, or an expression
1923 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1924 numerator and denominator of the aspect ratio.
1925 If the parameter is not specified, it is assumed the value "0:1".
1927 For example to change the sample aspect ratio to 10:11, specify:
1934 Set the timebase to use for the output frames timestamps.
1935 It is mainly useful for testing timebase configuration.
1937 It accepts in input an arithmetic expression representing a rational.
1938 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1939 default timebase), and "intb" (the input timebase).
1941 The default value for the input is "intb".
1943 Follow some examples.
1946 # set the timebase to 1/25
1949 # set the timebase to 1/10
1952 #set the timebase to 1001/1000
1955 #set the timebase to 2*intb
1958 #set the default timebase value
1964 Show a line containing various information for each input video frame.
1965 The input video is not modified.
1967 The shown line contains a sequence of key/value pairs of the form
1968 @var{key}:@var{value}.
1970 A description of each shown parameter follows:
1974 sequential number of the input frame, starting from 0
1977 Presentation TimeStamp of the input frame, expressed as a number of
1978 time base units. The time base unit depends on the filter input pad.
1981 Presentation TimeStamp of the input frame, expressed as a number of
1985 position of the frame in the input stream, -1 if this information in
1986 unavailable and/or meaningless (for example in case of synthetic video)
1992 sample aspect ratio of the input frame, expressed in the form
1996 size of the input frame, expressed in the form
1997 @var{width}x@var{height}
2000 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2001 for bottom field first)
2004 1 if the frame is a key frame, 0 otherwise
2007 picture type of the input frame ("I" for an I-frame, "P" for a
2008 P-frame, "B" for a B-frame, "?" for unknown type).
2009 Check also the documentation of the @code{AVPictureType} enum and of
2010 the @code{av_get_picture_type_char} function defined in
2011 @file{libavutil/avutil.h}.
2014 Adler-32 checksum of all the planes of the input frame
2016 @item plane_checksum
2017 Adler-32 checksum of each plane of the input frame, expressed in the form
2018 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2023 Split input video into several identical outputs.
2025 The filter accepts a single parameter which specifies the number of outputs. If
2026 unspecified, it defaults to 2.
2030 avconv -i INPUT -filter_complex split=5 OUTPUT
2032 will create 5 copies of the input video.
2036 Transpose rows with columns in the input video and optionally flip it.
2038 It accepts a parameter representing an integer, which can assume the
2043 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2051 Rotate by 90 degrees clockwise, that is:
2059 Rotate by 90 degrees counterclockwise, that is:
2067 Rotate by 90 degrees clockwise and vertically flip, that is:
2077 Sharpen or blur the input video.
2079 It accepts the following parameters:
2080 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2082 Negative values for the amount will blur the input video, while positive
2083 values will sharpen. All parameters are optional and default to the
2084 equivalent of the string '5:5:1.0:5:5:0.0'.
2089 Set the luma matrix horizontal size. It can be an integer between 3
2090 and 13, default value is 5.
2093 Set the luma matrix vertical size. It can be an integer between 3
2094 and 13, default value is 5.
2097 Set the luma effect strength. It can be a float number between -2.0
2098 and 5.0, default value is 1.0.
2100 @item chroma_msize_x
2101 Set the chroma matrix horizontal size. It can be an integer between 3
2102 and 13, default value is 5.
2104 @item chroma_msize_y
2105 Set the chroma matrix vertical size. It can be an integer between 3
2106 and 13, default value is 5.
2109 Set the chroma effect strength. It can be a float number between -2.0
2110 and 5.0, default value is 0.0.
2115 # Strong luma sharpen effect parameters
2118 # Strong blur of both luma and chroma parameters
2119 unsharp=7:7:-2:7:7:-2
2121 # Use the default values with @command{avconv}
2122 ./avconv -i in.avi -vf "unsharp" out.mp4
2127 Flip the input video vertically.
2130 ./avconv -i in.avi -vf "vflip" out.avi
2135 Deinterlace the input video ("yadif" means "yet another deinterlacing
2138 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2140 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2145 output 1 frame for each frame
2147 output 1 frame for each field
2149 like 0 but skips spatial interlacing check
2151 like 1 but skips spatial interlacing check
2156 @var{parity} specifies the picture field parity assumed for the input
2157 interlaced video, accepts one of the following values:
2161 assume top field first
2163 assume bottom field first
2165 enable automatic detection
2168 Default value is -1.
2169 If interlacing is unknown or decoder does not export this information,
2170 top field first will be assumed.
2172 @var{auto} specifies if deinterlacer should trust the interlaced flag
2173 and only deinterlace frames marked as interlaced
2177 deinterlace all frames
2179 only deinterlace frames marked as interlaced
2184 @c man end VIDEO FILTERS
2186 @chapter Video Sources
2187 @c man begin VIDEO SOURCES
2189 Below is a description of the currently available video sources.
2193 Buffer video frames, and make them available to the filter chain.
2195 This source is mainly intended for a programmatic use, in particular
2196 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2198 It accepts the following parameters:
2199 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
2201 All the parameters need to be explicitly defined.
2203 Follows the list of the accepted parameters.
2208 Specify the width and height of the buffered video frames.
2210 @item pix_fmt_string
2211 A string representing the pixel format of the buffered video frames.
2212 It may be a number corresponding to a pixel format, or a pixel format
2215 @item timebase_num, timebase_den
2216 Specify numerator and denomitor of the timebase assumed by the
2217 timestamps of the buffered frames.
2219 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2220 Specify numerator and denominator of the sample aspect ratio assumed
2221 by the video frames.
2226 buffer=320:240:yuv410p:1:24:1:1
2229 will instruct the source to accept video frames with size 320x240 and
2230 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2231 square pixels (1:1 sample aspect ratio).
2232 Since the pixel format with name "yuv410p" corresponds to the number 6
2233 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
2234 this example corresponds to:
2236 buffer=320:240:6:1:24
2241 Provide an uniformly colored input.
2243 It accepts the following parameters:
2244 @var{color}:@var{frame_size}:@var{frame_rate}
2246 Follows the description of the accepted parameters.
2251 Specify the color of the source. It can be the name of a color (case
2252 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2253 alpha specifier. The default value is "black".
2256 Specify the size of the sourced video, it may be a string of the form
2257 @var{width}x@var{height}, or the name of a size abbreviation. The
2258 default value is "320x240".
2261 Specify the frame rate of the sourced video, as the number of frames
2262 generated per second. It has to be a string in the format
2263 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2264 number or a valid video frame rate abbreviation. The default value is
2269 For example the following graph description will generate a red source
2270 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2271 frames per second, which will be overlayed over the source connected
2272 to the pad with identifier "in".
2275 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2280 Read a video stream from a movie container.
2282 Note that this source is a hack that bypasses the standard input path. It can be
2283 useful in applications that do not support arbitrary filter graphs, but its use
2284 is discouraged in those that do. Specifically in @command{avconv} this filter
2285 should never be used, the @option{-filter_complex} option fully replaces it.
2287 It accepts the syntax: @var{movie_name}[:@var{options}] where
2288 @var{movie_name} is the name of the resource to read (not necessarily
2289 a file but also a device or a stream accessed through some protocol),
2290 and @var{options} is an optional sequence of @var{key}=@var{value}
2291 pairs, separated by ":".
2293 The description of the accepted options follows.
2297 @item format_name, f
2298 Specifies the format assumed for the movie to read, and can be either
2299 the name of a container or an input device. If not specified the
2300 format is guessed from @var{movie_name} or by probing.
2302 @item seek_point, sp
2303 Specifies the seek point in seconds, the frames will be output
2304 starting from this seek point, the parameter is evaluated with
2305 @code{av_strtod} so the numerical value may be suffixed by an IS
2306 postfix. Default value is "0".
2308 @item stream_index, si
2309 Specifies the index of the video stream to read. If the value is -1,
2310 the best suited video stream will be automatically selected. Default
2315 This filter allows to overlay a second video on top of main input of
2316 a filtergraph as shown in this graph:
2318 input -----------> deltapts0 --> overlay --> output
2321 movie --> scale--> deltapts1 -------+
2324 Some examples follow:
2326 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2327 # on top of the input labelled as "in".
2328 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2329 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2331 # read from a video4linux2 device, and overlay it on top of the input
2333 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2334 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2340 Null video source, never return images. It is mainly useful as a
2341 template and to be employed in analysis / debugging tools.
2343 It accepts as optional parameter a string of the form
2344 @var{width}:@var{height}:@var{timebase}.
2346 @var{width} and @var{height} specify the size of the configured
2347 source. The default values of @var{width} and @var{height} are
2348 respectively 352 and 288 (corresponding to the CIF size format).
2350 @var{timebase} specifies an arithmetic expression representing a
2351 timebase. The expression can contain the constants "PI", "E", "PHI",
2352 "AVTB" (the default timebase), and defaults to the value "AVTB".
2356 Provide a frei0r source.
2358 To enable compilation of this filter you need to install the frei0r
2359 header and configure Libav with --enable-frei0r.
2361 The source supports the syntax:
2363 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
2366 @var{size} is the size of the video to generate, may be a string of the
2367 form @var{width}x@var{height} or a frame size abbreviation.
2368 @var{rate} is the rate of the video to generate, may be a string of
2369 the form @var{num}/@var{den} or a frame rate abbreviation.
2370 @var{src_name} is the name to the frei0r source to load. For more
2371 information regarding frei0r and how to set the parameters read the
2372 section @ref{frei0r} in the description of the video filters.
2374 Some examples follow:
2376 # generate a frei0r partik0l source with size 200x200 and framerate 10
2377 # which is overlayed on the overlay filter main input
2378 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2381 @section rgbtestsrc, testsrc
2383 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2384 detecting RGB vs BGR issues. You should see a red, green and blue
2385 stripe from top to bottom.
2387 The @code{testsrc} source generates a test video pattern, showing a
2388 color pattern, a scrolling gradient and a timestamp. This is mainly
2389 intended for testing purposes.
2391 Both sources accept an optional sequence of @var{key}=@var{value} pairs,
2392 separated by ":". The description of the accepted options follows.
2397 Specify the size of the sourced video, it may be a string of the form
2398 @var{width}x@var{height}, or the name of a size abbreviation. The
2399 default value is "320x240".
2402 Specify the frame rate of the sourced video, as the number of frames
2403 generated per second. It has to be a string in the format
2404 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2405 number or a valid video frame rate abbreviation. The default value is
2409 Set the sample aspect ratio of the sourced video.
2412 Set the video duration of the sourced video. The accepted syntax is:
2414 [-]HH[:MM[:SS[.m...]]]
2417 See also the function @code{av_parse_time()}.
2419 If not specified, or the expressed duration is negative, the video is
2420 supposed to be generated forever.
2423 For example the following:
2425 testsrc=duration=5.3:size=qcif:rate=10
2428 will generate a video with a duration of 5.3 seconds, with size
2429 176x144 and a framerate of 10 frames per second.
2431 @c man end VIDEO SOURCES
2433 @chapter Video Sinks
2434 @c man begin VIDEO SINKS
2436 Below is a description of the currently available video sinks.
2440 Buffer video frames, and make them available to the end of the filter
2443 This sink is intended for a programmatic use through the interface defined in
2444 @file{libavfilter/buffersink.h}.
2448 Null video sink, do absolutely nothing with the input video. It is
2449 mainly useful as a template and to be employed in analysis / debugging
2452 @c man end VIDEO SINKS