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Makefile
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documentation: $(addprefix doc/, developer.html faq.html ffmpeg-doc.html \
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                                 ffplay-doc.html ffserver-doc.html       \
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                                 general.html vfilters.html $(ALLMANPAGES))
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                                 general.html libavfilter.html $(ALLMANPAGES))
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doc/%.html: doc/%.texi
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	texi2html -monolithic -number $<
doc/libavfilter.texi
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\input texinfo @c -*- texinfo -*-
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@settitle Libavfilter Documentation
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@titlepage
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@sp 7
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@center @titlefont{Libavfilter Documentation}
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@sp 3
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@end titlepage
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@chapter Introduction
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Libavfilter is the filtering API of FFmpeg. It is the substitute of the
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now deprecated 'vhooks' and started as a Google Summer of Code project.
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Integrating libavfilter into the main FFmpeg repository is a work in
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progress. If you wish to try the unfinished development code of
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libavfilter then check it out from the libavfilter repository into
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some directory of your choice by:
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@example
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   svn checkout svn://svn.ffmpeg.org/soc/libavfilter
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@end example
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And then read the README file in the top directory to learn how to
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integrate it into ffmpeg and ffplay.
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But note that there may still be serious bugs in the code and its API
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and ABI should not be considered stable yet!
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@chapter Tutorial
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In libavfilter, it is possible for filters to have multiple inputs and
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multiple outputs.
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To illustrate the sorts of things that are possible, we can
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use a complex filter graph. For example, the following one:
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@example
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input --> split --> fifo -----------------------> overlay --> output
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            |                                        ^
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            |                                        |
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            +------> fifo --> crop --> vflip --------+
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@end example
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splits the stream in two streams, sends one stream through the crop filter
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and the vflip filter before merging it back with the other stream by
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overlaying it on top. You can use the following command to achieve this:
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@example
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./ffmpeg -i in.avi -s 240x320 -vfilters "[in] split [T1], fifo, [T2] overlay= 0:240 [out]; [T1] fifo, crop=0:0:-1:240, vflip [T2]
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@end example
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where input_video.avi has a vertical resolution of 480 pixels. The
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result will be that in output the top half of the video is mirrored
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onto the bottom half.
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Video filters are loaded using the @var{-vfilters} option passed to
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ffmpeg or to ffplay. Filters in the same linear chain are separated by
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commas. In our example, @var{split, fifo, overlay} are in one linear
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chain, and @var{fifo, crop, vflip} are in another. The points where
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the linear chains join are labeled by names enclosed in square
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brackets. In our example, that is @var{[T1]} and @var{[T2]}. The magic
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labels @var{[in]} and @var{[out]} are the points where video is input
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and output.
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Some filters take in input a list of parameters: they are specified
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after the filter name and an equal sign, and are separated each other
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by a semicolon.
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There exist so-called @var{source filters} that do not have a video
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input, and we expect in the future some @var{sink filters} that will
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not have video output.
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@chapter Available video filters
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When you configure your FFmpeg build, you can disable any of the
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existing video filters.
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The configure output will show the video filters included in your
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build.
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Below is a description of the currently available video filters.
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@section null
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Pass the source unchanged to the output.
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@bye
doc/vfilters.texi
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\input texinfo @c -*- texinfo -*-
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@settitle Video Filter Documentation
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@titlepage
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@sp 7
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@center @titlefont{Video Filter Documentation}
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@sp 3
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@end titlepage
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@chapter Introduction
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Libavfilter is the filtering API of FFmpeg. It is the substitute of the
14
now deprecated 'vhooks' and started as a Google Summer of Code project.
15

  
16
Integrating libavfilter into the main FFmpeg repository is a work in
17
progress. If you wish to try the unfinished development code of
18
libavfilter then check it out from the libavfilter repository into
19
some directory of your choice by:
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@example
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   svn checkout svn://svn.ffmpeg.org/soc/libavfilter
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@end example
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And then read the README file in the top directory to learn how to
26
integrate it into ffmpeg and ffplay.
27

  
28
But note that there may still be serious bugs in the code and its API
29
and ABI should not be considered stable yet!
30

  
31
@chapter Tutorial
32

  
33
In libavfilter, it is possible for filters to have multiple inputs and
34
multiple outputs.
35
To illustrate the sorts of things that are possible, we can
36
use a complex filter graph. For example, the following one:
37

  
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@example
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input --> split --> fifo -----------------------> overlay --> output
40
            |                                        ^
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            |                                        |
42
            +------> fifo --> crop --> vflip --------+
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@end example
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splits the stream in two streams, sends one stream through the crop filter
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and the vflip filter before merging it back with the other stream by
47
overlaying it on top. You can use the following command to achieve this:
48

  
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@example
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./ffmpeg -i in.avi -s 240x320 -vfilters "[in] split [T1], fifo, [T2] overlay= 0:240 [out]; [T1] fifo, crop=0:0:-1:240, vflip [T2]
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@end example
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53
where input_video.avi has a vertical resolution of 480 pixels. The
54
result will be that in output the top half of the video is mirrored
55
onto the bottom half.
56

  
57
Video filters are loaded using the @var{-vfilters} option passed to
58
ffmpeg or to ffplay. Filters in the same linear chain are separated by
59
commas. In our example, @var{split, fifo, overlay} are in one linear
60
chain, and @var{fifo, crop, vflip} are in another. The points where
61
the linear chains join are labeled by names enclosed in square
62
brackets. In our example, that is @var{[T1]} and @var{[T2]}. The magic
63
labels @var{[in]} and @var{[out]} are the points where video is input
64
and output.
65

  
66
Some filters take in input a list of parameters: they are specified
67
after the filter name and an equal sign, and are separated each other
68
by a semicolon.
69

  
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There exist so-called @var{source filters} that do not have a video
71
input, and we expect in the future some @var{sink filters} that will
72
not have video output.
73

  
74
@chapter Available video filters
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When you configure your FFmpeg build, you can disable any of the
77
existing video filters.
78
The configure output will show the video filters included in your
79
build.
80

  
81
Below is a description of the currently available video filters.
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@section null
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Pass the source unchanged to the output.
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@bye

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