[mythtv-users] OSS -vs- ALSA sound

[Harondel J. Sibble]

On 26 Sep 2003 at 11:08, Jarod C. Wilson wrote:

> Though I never did fully figure out how to fix my problem. I gave up, 
> and went dual sound cards... (just sent an update on the 
> "Double-audio..." thread).

I'm exploring the problem and have a semi working solution. Currently, I 
pulled the spdif cable off my dxr3 and plugged it into the spdif out on my 
digital i/o card. All audio now goes through this one connection as I've 
unplugged the analog front and rear channel cables to the DesktopTheatre amp.

Kmix is virtually useless in this environment. Alsamixer and/or gamixer bith 
show you all the mixer choices (and there are a lot of them!!! gamixer 
actually shows more, but from my reading some of those features aren't yet 
supported by alsa)

the following options line enables all i/o ports for the sb live/audigy 
family

options snd-emu10k1 snd_extin=0x3fff snd_extout=0x1fff

Audio for mythtv is controlled by the playback ac97slider, audio for analog 
cdrom connection is controlled by (in alsamixer) iec958 ttl line live dr, 
note iec958 optical raw must be diabled (off in alsamixer).  In gamixer, you 
use the slider just to the right of ttl capture. I haven't figured out how to 
get digital cd audio working (2 pin cable from cdrom) yet. :-(

Ideally I'd rather use the mini din connector on the digital io card or the 
mini digital din on the 5.1 card itself as AFAIK, those connectors will route 
the right sound to the right speakers whether you are using an amp or not.


Supposedly, you just hook your coax cable up to a stereo mini rca converter 
plugged into the analog/digital mini din on the card and it works, in my case 
it doesn't :-(

Currently 4 point surround on the amp does not work.  Putting it into dolby 
prologic digital mode makes the centre channel quite loud while analog 
prologic does nothing. Music, movie and stereo fourpoint vary the the use of 
the centre channel, none of these 3 enable rear channel. Prologic does very 
quietly. With no lights on on the amp, it's just like with music,movie etc.

> What sort of conflict? You definitely have to only use one or the 
> other...

For some reason, kmod is loading the oss kernel drivers, even though 
/etc/modules.conf says to load alsa.  Turns out some of my module options 
were actually for OSS rather than alsa, so it was choking on alsa and then 
defaulting to oss. I've since got that resolved.


-- 
Harondel J. Sibble 
Sibble Computer Consulting
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