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doc/ffmpeg.texi: apply misc fixes to the -map_channel documentation

This commit is contained in:
Stefano Sabatini 2012-03-03 19:19:40 +01:00
parent bf807a5e87
commit 4ecfb91b85

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@ -798,7 +798,7 @@ Note that using this option disables the default mappings for this output file.
@item -map_channel [@var{input_file_id}.@var{stream_specifier}.@var{channel_id}|-1][:@var{output_file_id}.@var{stream_specifier}]
Map an audio channel from a given input to an output. If
@var{output_file_id}.@var{stream_specifier} are not set, the audio channel will
@var{output_file_id}.@var{stream_specifier} is not set, the audio channel will
be mapped on all the audio streams.
Using "-1" instead of
@ -820,18 +820,18 @@ The order of the "-map_channel" option specifies the order of the channels in
the output stream. The output channel layout is guessed from the number of
channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac"
in combination of "-map_channel" makes the channel gain levels to be updated if
channel layouts don't match (for instance two "-map_channel" options and "-ac
6").
input and output channel layouts don't match (for instance two "-map_channel"
options and "-ac 6").
You can also extract each channel of an @var{INPUT} to specific outputs; the
following command extract each channel of the audio stream (file 0, stream 0)
to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1}:
You can also extract each channel of an input to specific outputs; the following
command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0)
to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs:
@example
ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1
@end example
The following example split the channels of a stereo input into streams:
The following example splits the channels of a stereo input into two separate
streams, which are put into the same output file:
@example
ffmpeg -i stereo.wav -map 0:0 -map 0:0 -map_channel 0.0.0:0.0 -map_channel 0.0.1:0.1 -y out.ogg
@end example
@ -841,14 +841,13 @@ input stream; you can't for example use "-map_channel" to pick multiple input
audio channels contained in different streams (from the same or different files)
and merge them into a single output stream. It is therefore not currently
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
stream. However splitting 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):
video stream), you can use the following command:
@example
ffmpeg -i input.mkv -f lavfi -i "
amovie=input.mkv:si=1 [a1];