Document the preset files system.

Originally committed as revision 15563 to svn://svn.ffmpeg.org/ffmpeg/trunk
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Stefano Sabatini 2008-10-05 09:45:54 +00:00
parent 5b9ce252a9
commit 4a60e574bb

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@ -780,6 +780,40 @@ Set the maximum demux-decode delay.
Set the initial demux-decode delay.
@end table
@section Preset files
A preset file contains a sequence of @var{option}=@var{value} pairs,
one for each line, specifying a sequence of options which would be
awkward to specify on the command line. Lines starting with the hash
('#') character are ignored and are used to provide comments. Check
the @file{ffpresets} directory in the FFmpeg source tree for examples.
Preset files are specified with the @code{vpre}, @code{apre} and
@code{spre} options. The options specified in a preset file are
applied to the currently selected codec of the same type as specified
by the preset option.
The argument passed to the preset options identifies the preset file
to use according to the following rules.
First ffmpeg searches for a file named @var{arg}.ffpreset in the
directories @file{$HOME/.ffmpeg}, @file{/usr/local/share/ffmpeg} and
@file{/usr/share/ffmpeg} in that order. For example, if the argument
is @code{libx264-max}, it will search for the file
@file{libx264-max.ffpreset}.
If no such file is found, then ffmpeg will search for a file named
@var{codec_name}-@var{arg}.ffpreset in the above-mentioned
directories, where @var{codec_name} is the name of the codec to which
the preset file options will be applied. For example, if you select
the video codec with @code{-vcodec libx264} and use @code{-vpre max},
then it will search for the file @file{libx264-max.ffpreset}.
Finally, if the above rules failed and the argument specifies an
absolute pathname, ffmpeg will search for that filename. This way you
can specify the absolute and complete filename of the preset file, for
example @file{./ffpresets/libx264-max.ffpreset}.
@node FFmpeg formula evaluator
@section FFmpeg formula evaluator