[FFmpeg-user] Multiple audio tracks

Carl Eugen Hoyos cehoyos at ag.or.at
Thu Dec 1 15:37:50 CET 2011

Mike Rotondo <Rbigm101 <at> gmail.com> writes:

> Here is the mediainfo output

I do not remember a report where this was useful ...

> Channel positions                : Front: L C R, Side: L R, Back: L R, LFE

... otoh, this looks interesting (I thought the AAC specification required 8
channel audio to be "wide" - C LC L RC R BL BR LFE):
If you extract the audio stream - ffmpeg -i Sample.mkv -acodec copy -map 0.1
out.aac or mplayer -dumpaudio - do the positions look identical? If yes, could
you provide the sample (audio only)?


> I don't think the fact that there is 8 channels in the audio is hurting it.


> Here's the output:
> ffmpeg version 0.8.7, Copyright (c) 2000-2011 the FFmpeg developers

If you are a user (and not a distributor), please consider using current git
head: It contains less bugs and more features than any released version.


>     Stream #0.1(eng): Audio: aac, 48000 Hz, 7.1(wide), s16

The (Dolby) specification that the ac3 encoder implements does not allow 8
channels, you have to either downmix audio (with -ac) or choose another stream
to encode (with -map).

Carl Eugen

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