Hi everyone,
before my latest upgrade to Linux 2.6.32 (yes, sorry, it's Debian), I had four levers in my alsamixer: VIA DXS, VIA DXS 1, VIA DXS 2 and VIA DXS 3. They controlled the hardware mixing when accessing the sound device multiple times.
Now they have disappeared. I think I can pretty certainly trace this down to commit 2fb930b53f513cbc4c102d415d2923a8a7091337 to Linux [http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.32.y.git;a=commit...], which "move[s] DXS volume controls to PCM interface".
As I'm not an ALSA developer, I don't realize the intended effect of this change, but the actual effect is that I cannot change the DXS volumes any more. mplayer still controls the global PCM volume. Well, in fact, there is one way. While an mplayer is running, I can do:
amixer cset numid=47,iface=PCM,name='PCM Playback Volume' 24,24
When restarting mplayer, the volume is reset to 31,31 (maximum). Commit 3d00941371a765779c4e3509214c7e5793cce1fe [http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.33.y.git;a=commit...] seems to be responsible for this.
The bad thing about it is that 31,31 is a really bad setting for my poorly engineered sound card. It distorts a lot.
I suspect that the real *bug* is that mplayer does not use the per-channel DXS controls even though it's supposed to (which seems to be why the DXS controls are called "PCM Playback Volume").
Personally, rather than fixing this bug, I would just revert to the former state. I was always happy with all the DXS levers set to 75%.
Thank you
Sören