[FFmpeg-user] swopping channels in a 5.1 layout

Youri Feenstra youri.feenstra at gmail.com
Sun Jan 29 14:46:14 CET 2012

Hi all,
I'm trying to reverse left and right audio channels from a 5.1 audio source.
My command is
ffmpeg -i 6.wav -map_channel 0.0.1 -map_channel 0.0.0 -map_channel 0.0.2
-map_channel 0.0.3 -map_channel 0.0.5 -map_channel 0.0.4 -y 6rev.wav

But the resulting file will sound exactly the same.
However, when I downmix to two channels, like so
ffmpeg -i 6.wav -ac 2 -map_channel 0.0.1 -map_channel 0.0.0 -map_channel
0.0.2 -map_channel 0.0.3 -map_channel 0.0.5 -map_channel 0.0.4 -y 2rev.wav

...the resulting audio will have the left and right channels swopped. The
fact that this will be a 2-channeld audio stream isn't a big problem since
I'll be using this command on video files which I will play on my phone
with headphones.
But, downmixing results in a much lower volume, which is an issue for me.

Does anyone know why the map_channel option won't work on a 5.1 output


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