[mythtv-users] ALSA and SPDIF Out For nForce2 Motherboards

[Michael T. Dean]

KianTeck wrote:

> Did as advised: commented out the slave.pcm  "digital" and removed the 
> comment  for slave.pcm  "dmix-digital".  I then made the change in 
> MythTV from "ALSA:digital" to "ALSA:dmix-digital" for the "Audio 
> output device".  Rebooted the machine but still no joy.  I'm able to 
> get sound out via the analog output if I change "Audio output device" 
> back to default of "/dev/dsp".

That's the problem.  The section that I just had you change was the 
section that defined a device called "default" (not called 
"dmix-digital").  In other words, the default device is the device used 
when no device is specified (i.e. a program uses the ALSA API but 
doesn't request a specific device) or when the "default" device is 
requested (i.e. for Myth, "ALSA:default").

I suppose I should have included a nice comment at the top of the 
.asoundrc listing all the valid devices defined within.  Anyway, the 
only devices you should ever use are:

analog
mixed-analog
digital
mixed-digital
default

Note that if you leave the entire definition of "pcm.!default" 
commented, default will be identical to analog.  If you redefine default 
by uncommenting the 4-line definition of "pcm.!default" default will be 
identical to the device associated with the uncommented slave definition 
(mixed-analog, digital, or mixed-digital from top to bottom as shown in 
the .asoundrc I posted at 
http://www.gossamer-threads.com/perl/mailarc/gforum.cgi?post=119212&t=search_engine#119212 
).

All other names in the .asoundrc--including "dmix-digital" are for 
internal use only--they are virtual devices created as aliases to allow 
reuse within the file.

So, try using "ALSA:digital" or "ALSA:mixed-digital" and see how it 
works.  (Or you could use "ALSA:default"--if you leave your .asoundrc as 
is (based on the change you just made), this will be the same as using 
"ALSA:mixed-digital")

Mike

BTW, that also means that there wasn't necessarily another program using 
your audio device.  Therefore, you can try both "ALSA:digital" and 
"ALSA:mixed-digital" and use whichever you prefer.  I recommend testing 
by watching some TV and causing the computer to play other noises (i.e. 
ssh to the computer and issue an aplay) to see how sound behaves.  If 
using "digital," the sounds will "queue up" (most likely causing the 
application waiting for sound--here aplay--to block), but if using 
"mixed-digital," the sounds will play (so the applications won't block).

Also, when you finish watching TV with unmixed output, you'll hear all 
the sounds that got queued up--on my system, they play back much louder 
than my videos, so it's quite scary to stop a playing video.  Because of 
that (and because the other sounds usually mean something), I'm using 
mixed output (analog in my case because I'm hooked directly to the 
speakers).