[mythtv-users] Transcoding 5.1 audio yields useless files

Rod Smith mythtv at rodsbooks.com
Sat Dec 5 22:49:34 UTC 2009


I'm trying to resolve a long-time problem that's been a minor annoyance in the 
past but that's likely to become more significant for me in the future: On 
one of my two backends, transcoding recordings with 5.1 audio produces files 
that play at reduced speed with slow and out-of-sync audio (it sounds 
something like an old-fashioned record played at too slow a speed). My other 
backend transcodes the files fine, although it converts 5.1-channel audio to 
2 channels.

The system that transcodes OK is running 64-bit Ubuntu 8.04 with the MythTV 
0.21 binaries from the Ubuntu repositories. The one that gives me problems 
was originally 32-bit Ubuntu 6.10 running locally-compiled MythTV 0.21, but 
I've since upgraded to 64-bit Ubuntu 9.10 with a locally-compiled MythTV 
0.21. I've recently (today) upgraded the 9.10 system to MythTV 0.22 using the 
binaries from the Ubuntu repositories. (Upgrading the second backend is 
taking longer, since I'm having to compile Qt and MythTV from scratch.) I'd 
hoped the 0.22 upgrade would fix the problem, but it hasn't.

So any clues as to what's going on? Is there some workaround I can use? I'm 
looking into creating a user job to do the transcoding instead (and ideally 
preserve the 5.1 audio), but I don't yet have anything that works quite 

FWIW, this is becoming important because I'm recording more HD content with 
5.1 audio, some of which I don't want to watch immediately, so I'd prefer to 
transcode it to a more compact format to save disk space.

Rod Smith

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