@settitle Libavfilter Documentation
@titlepage
-@sp 7
@center @titlefont{Libavfilter Documentation}
-@sp 3
@end titlepage
+@top
-@chapter Introduction
-
-Libavfilter is the filtering API of FFmpeg. 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
-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:
+@contents
-@example
- svn checkout svn://svn.ffmpeg.org/soc/libavfilter
-@end example
+@chapter Introduction
-And then read the README file in the top directory to learn how to
-integrate it into ffmpeg and ffplay.
+Libavfilter is the filtering API of Libav. It replaces 'vhooks', and
+started as a Google Summer of Code project.
-But note that there may still be serious bugs in the code and its API
+Note that there may still be serious bugs in the code and its API
and ABI should not be considered stable yet!
@chapter Tutorial
+------> fifo --> crop --> vflip --------+
@end example
-splits the stream in two streams, sends one stream through the crop filter
-and the vflip filter before merging it back with the other stream by
+splits the stream in two streams, then sends one stream through the crop filter
+and the vflip filter, before merging it back with the other stream by
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]
+./avconv -i input -vf "[in] split [T1], fifo, [T2] overlay=0:H/2 [out]; [T1] fifo, crop=iw:ih/2:0:ih/2, vflip [T2]" output
@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.
+The result will be that the top half of the video is mirrored
+onto the bottom half of the output video.
-Video filters are loaded using the @var{-vfilters} option passed to
-ffmpeg or to ffplay. 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
-brackets. In our example, that is @var{[T1]} and @var{[T2]}. The magic
+Video filters are loaded using the @var{-vf} option passed to
+avconv or to avplay. Filters in the same linear chain are separated by
+commas. In our example, @var{split}, @var{fifo}, and @var{overlay} are in one
+linear chain, and @var{fifo}, @var{crop}, and @var{vflip} are in another. The
+points where the linear chains join are labeled by names enclosed in square
+brackets. In our example, they join at @var{[T1]} and @var{[T2]}. The magic
labels @var{[in]} and @var{[out]} are the points where video is input
and output.
-Some filters take in input a list of parameters: they are specified
-after the filter name and an equal sign, and are separated each other
+Some filters take a list of parameters: they are specified
+after the filter name and an equal sign, and are separated
by a semicolon.
-There exist so-called @var{source filters} that do not have a video
-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.
+There are so-called @var{source filters} that do not take video
+input, and we expect that some @var{sink filters} will
+not have video output, at some point in the future.
-@section crop
+@chapter graph2dot
-Crop the input video to x:y:width:height.
+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 "crop=0:0:0:240" out.avi
+graph2dot -h
@end example
-``x'' and ``y'' specify the position of the top-left corner of the
-output (non-cropped) area.
+to see how to use @file{graph2dot}.
-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:
+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
-"crop=100:100:0:0"
+echo @var{GRAPH_DESCRIPTION} | \
+tools/graph2dot -o graph.tmp && \
+dot -Tpng graph.tmp -o graph.png && \
+display graph.png
@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
+can be used to create and display an image representing the graph
+described by the @var{GRAPH_DESCRIPTION} string.
-Convert the input video to one of the specified pixel formats.
-Libavfilter will try to pick one that is supported for the input to
-the next filter.
-
-The filter accepts a list of pixel format names, separated by ``:'',
-for example ``yuv420p:monow:rgb24''.
-
-The following command:
-
-@example
-./ffmpeg -i in.avi -vfilters "format=yuv420p" out.avi
-@end example
-
-will convert the input video to the format ``yuv420p''.
-
-@section noformat
-
-Force libavfilter not to use any of the specified pixel formats for the
-input to the next filter.
-
-The filter accepts a list of pixel format names, separated by ``:'',
-for example ``yuv420p:monow:rgb24''.
-
-The following command:
-
-@example
-./ffmpeg -i in.avi -vfilters "noformat=yuv420p, vflip" out.avi
-@end example
-
-will make libavfilter use a format different from ``yuv420p'' for the
-input to the vflip filter.
-
-@section null
-
-Pass the source unchanged to the output.
-
-@section vflip
-
-Flip the input video vertically.
-
-@example
-./ffmpeg -i in.avi -vfilters "vflip" out.avi
-@end example
+@include filters.texi
@bye
projects / ffmpeg / blobdiff