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doc: document amerge filter as an alternative for the -map_channel limitation.

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Clément Bœsch 2012-01-10 11:47:46 +01:00 committed by Clément Bœsch
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12
doc/ffmpeg.texi
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@ -835,6 +835,18 @@ possible, for example, to turn two separate mono streams into a single stereo
stream. However spliting a stereo stream into two single channel mono streams
is possible.
If you need this feature, a possible workaround is to use the @emph{amerge}
filter. For example, if you need to merge a media (here @file{input.mkv}) with 2
mono audio streams into one single stereo channel audio stream (and keep the
video stream):
@example
ffmpeg -i input.mkv -f lavfi -i "
amovie=input.mkv:si=1 [a1];
amovie=input.mkv:si=2 [a2];
[a1][a2] amerge" -c:a pcm_s16le -c:v copy output.mkv
@end example
@item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
Set metadata information of the next output file from @var{infile}. Note that
those are file indices (zero-based), not filenames.

17
doc/filters.texi
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@ -189,6 +189,23 @@ Example: merge two mono files into a stereo stream:
amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
@end example
If you need to do multiple merges (for instance multiple mono audio streams in
a single video media), you can do:
@example
ffmpeg -f lavfi -i "
amovie=input.mkv:si=0 [a0];
amovie=input.mkv:si=1 [a1];
amovie=input.mkv:si=2 [a2];
amovie=input.mkv:si=3 [a3];
amovie=input.mkv:si=4 [a4];
amovie=input.mkv:si=5 [a5];
[a0][a1] amerge [x0];
[x0][a2] amerge [x1];
[x1][a3] amerge [x2];
[x2][a4] amerge [x3];
[x3][a5] amerge" -c:a pcm_s16le output.mkv
@end example
@section anull
Pass the audio source unchanged to the output.