[mythtv] SPDIF and Myth (was MythMusic)

[Rick Warner]

On Tuesday 11 November 2003 20:41, Desmond Rivet wrote:
> Hi all,
>
> I managed to get SPDIF out working on my MythTV system with ALSA. I took
> out the SB5.1 I was using and I'm now using the AD1980 chip that comes on
> board my P4PE. The sound chip comes with an optical output which I'm
> plugging into my receiver.
>
> It's working but...does anyone else notice that the quality is rather poor
> when playing MP3s or CDs via MythMusic, using the digital out? I'm not
> exactly sure how to fix this, or if there's even anything to be fixed. And
> I'm not even sure what frequency I'm supposed to be seeing in my receiver -
> currently it shows 48Khz whenever sound is played, whether it's a MP3, CD
> or MPEG2 recording ( I have a PVR-350).
>
> I'm afraid I can't be much more specific than that, except that the music
> coming out of my speakers sounds like it got saturated at some pre-receiver
> stage. I was having the same sorts of quality problems with MythMusic
> before and the solution was to turn down the master volume on the sound
> card and turn up the volume on my receiver. This doesn't seem to be
> possible with digital out.
>
> Thanks for any ideas.
>
> Desmond
>
I don't know if you've gotten help on this since then, but here is my working 
setup:
sb live 5.1 (oem of cheapest model there is)- using a mono headphone jack to 
rca cable converter thing for the "coaxial" digital input into my receiver
audio output of cable box (i use an ir transmitter for changing channels) goes 
into line in on sound card.  ONLY output to receiver is via the digital out.

using alsa 0.9.8 drivers.  No special params for alsa module loading.  
Attached is the asound.state (i think some distros call it asound.conf 
instead) file for my setup.  My music sounds great.  For mythdvd, this is the 
command i use to play the ac3 track straight through the digital connection 
and let my receiver do the decoding for true 5.1 sound- 
mplayer dvd://1 -dvd-device %d -fs -aid 128 -cache 8192 -ac hwac3 -ao 
alsa9:mmap:noblock

If this doesn't work, try -dvd 1 instead of dvd://1    Mplayer just changed to 
dvd://1 in recent versions