[mythtv-users] trandcoding messes up 6 channel audio slow audio playback

Gavin Hurlbut gjhurlbu at gmail.com
Fri Dec 31 07:03:49 UTC 2010

On Thu, Dec 30, 2010 at 8:48 PM, Jean-Yves Avenard <jyavenard at gmail.com> wrote:
> I wasn't aware that it wouldn't even properly transcode 5.1 audio into
> stereo either.

I can confirm that this is the case in all my testing.  Any time
mythtranscode (particularly when using the --fifo mode) is sourced 5.1
AC3 audio, it spits out 6 channels of 48kHz 16-bit PCM.  In nuvexport,
I use sox to downmix that to stereo, but if we can get the mythtv
internal downmixer working in that case, that would be so much nicer.

What we could have is:  if you are using --fifodir, always downmix to
stereo PCM for output *unless* the user says --fifo-passthru or
something, in which case, you just pass the audio stream out the fifo
unmolested?  This would be nice for archiving with the AC3 (or AAC in
some cases) in place.

I also was planning at some point to add in --fifo-audio-only and
--fifo-video-only to further simplify the main use case (nuvexport).
But I haven't gotten there yet :)

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