[FFmpeg-user] How to crop extra audio channels?

Carl Eugen Hoyos cehoyos at ag.or.at
Sat Mar 17 12:46:18 CET 2012

Deron <deron <at> pagestream.org> writes:

> ffmpeg -i "file.mov" -f s8 -vn -ac 2 -ar 48000 -acodec pcm_s8 -y 
> "file.audio"

Sorry for my first comment, please try the following and report back:
ffmpeg -i file.mov -f s8 -map_channel 0.0.1 -map_channel 0.0.2 file.audio

As explained in ticket #1088, -ac 2 would downmix from 16 to two channels, 
since the layout for 16 channels is unknown, this is generally impossible.

Carl Eugen

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