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

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Stefano Sabatini 2012-03-03 19:19:40 +01:00
parent bf807a5e87
commit 4ecfb91b85
1 changed files with 10 additions and 11 deletions
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doc/ffmpeg.texi
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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}] @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 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. be mapped on all the audio streams.
Using "-1" instead of 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 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" 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 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 input and output channel layouts don't match (for instance two "-map_channel"
6"). options and "-ac 6").
You can also extract each channel of an @var{INPUT} to specific outputs; the You can also extract each channel of an input to specific outputs; the following
following command extract each channel of the audio stream (file 0, stream 0) command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0)
to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1}: to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs:
@example @example
ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1 ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1
@end example @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 @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 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 @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) 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 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 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. is possible.
If you need this feature, a possible workaround is to use the @emph{amerge} 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 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 mono audio streams into one single stereo channel audio stream (and keep the
video stream): video stream), you can use the following command:
@example @example
ffmpeg -i input.mkv -f lavfi -i " ffmpeg -i input.mkv -f lavfi -i "
amovie=input.mkv:si=1 [a1]; amovie=input.mkv:si=1 [a1];