[mythtv-users] Audio issues with .21 - very quiet washed out sound

Matt S. skd5aner at gmail.com
Mon Mar 10 18:43:22 UTC 2008


On Sun, Mar 9, 2008 at 11:38 PM, Yeechang Lee <ylee at pobox.com> wrote:
> Michael T. Dean <mtdean at thirdcontact.com> says:
> > > Problem went away when I switched upmix from 5.1 to 2 channels.
> > > Not sure that's desirable - but at least I can hear sound now.
> >
> > 2 channels is correct for S/PDIF.
>
> That can't be right, as bug #4819 describes. Why would audio be
> properly decoded in Passive upmix mode with 5.1, but not with the two
> Active modes? Why is there an issue with MPEG-4 files, but not MPEG-2?
> Why Xvid, but not Divx?
>
> One of the reasons for the multichannel audio added in #1104 was to
> permit timestretched recordings to retain any 5.1 tracks. With the
> Active upmix settings, setting Max Audio Channels to Stereo prevents
> this feature from working (and, worse, returning to 1.0 time doesn't
> return the 5.1 audio).
>
>

Yea, I'm no expert, but it doesn't really make much sense to me
either.  I was REALLY looking forward to the ability to timestretch
AC3 encoded audio without losing the multi-channels (via SPDIF) to my
receiver.  I thought the idea was that we could use software decoding
to decode the AC3 stream, timestretch, then re-encode and pass-through
to the receiver.  In addition, I'm not sure why when I select 5.1
upmix that it basically destroys the sound?  Why doesn't it send a
valid 5.1 signal over SPDIF to my receiver?

Seems to me like this solutions, as much as I'm pulling for it, isn't
completely baked yet.  Hopefully since .21 is now released to the
masses, Mark, Janne, and folks will have enough feedback to make this
a little more rock solid.

Thanks!
Matt


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