@settitle Libavfilter Documentation
@titlepage
-@sp 7
@center @titlefont{Libavfilter Documentation}
-@sp 3
@end titlepage
+@top
+
+@contents
@chapter Introduction
-Libavfilter is the filtering API of FFmpeg. It is the substitute of the
+Libavfilter is the filtering API of Libav. It is the substitute of the
now deprecated 'vhooks' and started as a Google Summer of Code project.
-Integrating libavfilter into the main FFmpeg repository is a work in
+Integrating libavfilter into the main Libav repository is a work in
progress. If you wish to try the unfinished development code of
libavfilter then check it out from the libavfilter repository into
some directory of your choice by:
@example
- svn checkout svn://svn.ffmpeg.org/soc/libavfilter
+ svn checkout svn://svn.libav.org/soc/libavfilter
@end example
And then read the README file in the top directory to learn how to
-integrate it into ffmpeg and ffplay.
+integrate it into ffmpeg and avplay.
But note that there may still be serious bugs in the code and its API
and ABI should not be considered stable yet!
overlaying it on top. You can use the following command to achieve this:
@example
-./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]
+./ffmpeg -i in.avi -s 240x320 -vf "[in] split [T1], fifo, [T2] overlay= 0:240 [out]; [T1] fifo, crop=0:0:-1:240, vflip [T2]
@end example
where input_video.avi has a vertical resolution of 480 pixels. The
result will be that in output the top half of the video is mirrored
onto the bottom half.
-Video filters are loaded using the @var{-vfilters} option passed to
-ffmpeg or to ffplay. Filters in the same linear chain are separated by
+Video filters are loaded using the @var{-vf} option passed to
+ffmpeg or to avplay. Filters in the same linear chain are separated by
commas. In our example, @var{split, fifo, overlay} are in one linear
chain, and @var{fifo, crop, vflip} are in another. The points where
the linear chains join are labeled by names enclosed in square
input, and we expect in the future some @var{sink filters} that will
not have video output.
-@chapter Available video filters
-
-When you configure your FFmpeg build, you can disable any of the
-existing video filters.
-The configure output will show the video filters included in your
-build.
-
-Below is a description of the currently available video filters.
-
-@section crop
-
-Crop the input video to x:y:width:height.
-
-@example
-./ffmpeg -i in.avi -vfilters "crop=0:0:0:240" out.avi
-@end example
-
-``x'' and ``y'' specify the position of the top-left corner of the
-output (non-cropped) area.
-
-The default value of ``x'' and ``y'' is 0.
-
-The ``width'' and ``height'' parameters specify the width and height
-of the output (non-cropped) area.
-
-A value of 0 is interpreted as the maximum possible size contained in
-the area delimited by the top-left corner at position x:y.
-
-For example the parameters:
-
-@example
-"crop=100:100:0:0"
-@end example
-
-will delimit the rectangle with the top-left corner placed at position
-100:100 and the right-bottom corner corresponding to the right-bottom
-corner of the input image.
-
-The default value of ``width'' and ``height'' is 0.
-
-@section format
+@chapter graph2dot
-Convert the input video to one of the specified pixel formats.
-Libavfilter will try to pick one that is supported as the input to
-the next filter.
-
-The filter takes as argument a list of pixel format names, separated
-by ``:'', for example ``yuv420p:monow:rgb24''.
-
-The following command:
+The @file{graph2dot} program included in the Libav @file{tools}
+directory can be used to parse a filter graph description and issue a
+corresponding textual representation in the dot language.
+Invoke the command:
@example
-./ffmpeg -i in.avi -vfilters "format=yuv420p" out.avi
+graph2dot -h
@end example
-will convert the input video to the format ``yuv420p''.
-
-@section noformat
-
-Force libavfilter not to use any of the specified pixel formats as the
-input to the next filter.
+to see how to use @file{graph2dot}.
-The filter takes as argument a list of pixel format names, separated
-by ``:'', for example ``yuv420p:monow:rgb24''.
-
-The following command:
+You can then pass the dot description to the @file{dot} program (from
+the graphviz suite of programs) and obtain a graphical representation
+of the filter graph.
+For example the sequence of commands:
@example
-./ffmpeg -i in.avi -vfilters "noformat=yuv420p, vflip" out.avi
+echo @var{GRAPH_DESCRIPTION} | \
+tools/graph2dot -o graph.tmp && \
+dot -Tpng graph.tmp -o graph.png && \
+display graph.png
@end example
-will make libavfilter use a format different from ``yuv420p'' as the
-input to the vflip filter.
-
-@section null
-
-Pass the source unchanged to the output.
-
-@section vflip
+can be used to create and display an image representing the graph
+described by the @var{GRAPH_DESCRIPTION} string.
-Flip the input video vertically.
-
-@example
-./ffmpeg -i in.avi -vfilters "vflip" out.avi
-@end example
+@include filters.texi
@bye
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