Re: [gentoo-user] Setting basic ALSA defaults

On Wed, Apr 25, 2012 at 07:58:54PM +0100, Stroller wrote:
> Hi guys,
>
> I've got a a little nettop which I'm trying to set up for XBMC. As I don't normally use Linux on the desktop, but primarily for headless servers, this has been a little bit of a journey for me, but I now have X11 and the nVidia drivers working, and basic audio playback.
>
> So this particular system (eMachines 1401) defaults to the headphone output, and I've learned that to get it to output over HDMI I have to run:
>      aplay -vvD plug:hdmi file.wav
>
> I also, then, have to enter alsamixer and unmute the "S/PDIF 1" output (that seems to be muted by default on this system) and audio starts coming through on the TV.
>
> So I want to set, of course, HDMI as the default output, so I created an /etc/asound.conf and put the following in it:
>
>   pcm.!default {
>         type hw
>         card 0
>         device 3
>   }
>
>   ctl.!default {
>         type hw
>         card 0
>         device 3
>   }
>
>
> This is great! Now when I run aplay I can omit the "-D $devicename" flag and everything's good.
>
> Now I have to admit, I figured out the above more or less by trial and error (that, for instance, I can't describe the output as "card 0,3", but I have to have the separate device line), and the "pcm" and "ctl" parts, and the structure I just copied of the documentation at the ALSA website. I don't find that documentation very clear.
>
> So this is problematic the next time I reboot, because all of a sudden, now alsamixer doesn't work. In fact, I can demonstrate that the problem is related directly to this file:
>
> # alsamixer
> cannot open mixer: Invalid argument
> # rm /etc/asound.conf
> # alsamixer
> # echo $?
> 0
> #
>
> So could anyone possibly explain this for me, please?
>
> I'm liable to have another question or two in a moment, but I'd initially just really love to understand why the alsa documentation says to have separate pcm.!default and ctl.!default definitions (instead of a single "everything.!default) and why alsamixer has now broke.
>
> Many thanks in advance for any help you can offer,
>
> Stroller.

Just a shot in the dark here, Stroller, but I once had a problem with using
a mixer app (not alsamixer, which worked). I couldn't get it to start, and
it kept on giving an error like your's above for alsamixer. The problem was
that the kernel module, snd-mixer-oss was not loading by default, and when I
loaded that module, all was good. HTH.

Terry