[mythtv-users] Soft/garbled audio with SVN

[Curtis Stanford]

On 25-Feb-08, at 2:52 AM, Yeechang Lee wrote:

> For those experiencing problems with audio while running SVN (such as
> Curtis Stanford, at
> <URL:http://www.gossamer-threads.com/lists/mythtv/users/ 
> 318588#318588>),
> the cause may be the new audio upmix feature (ticket #1104) recently
> merged into trunk.
>
> My frontend is connected via S/PDIF to a 5.1 receiver, with AC3 and
> DTS passthrough enabled. Here's my experience with various recordings'
> audio sources with #1104 and the Active Simple or Active Linear
> upmix settings:
>
> * MPEG-2, AC3 audio: No issues[1].
> * MPEG-2, non-AC3 audio: No issues.
> * MPEG-4, non-AC3 audio (generated via mythtranscode from MPEG-2 and,
>  usually, AC3): Very soft music. Voices are almost inaudible even at
>  very high volume.
>
> Shifting to Passive seems to fix the issue with the MPEG-4
> files. #1104 (the only place I can find any relevant documentation at
> all on the topic) states that the Active Simple and Active Linear
> settings require more CPU. My frontend is a Pentium 3.0GHz; who'd have
> figured that audio decoding (as opposed to video) would be so
> CPU-intensive? In any case, I've uploaded a patch (#4775) that may
> help in avoiding some future confusion.
>
> [1] As far as I can tell; I'm no audiophile and perhaps I'm missing
> some nuance those with keener ears would pick up instantly.

That's not the same problem I reported. I'm not using passthrough,  
just converting to stereo to my TV speakers. Who knows, it may still  
be caused by these changes you mentioned. I've tried playing with  
those settings as well.

Curtis