Solution: 2 sound cards; setting one as default

Question

I've got 2 sound cards in my system: one onboard and one an add-in PCI card. I want to make the better card, the PCI card, the default. But the system seems to detect the onboard sound card first and wants to make it the default card.
I'm coming from Debian/Ubuntu where I had found a solution for this problem. I can't recall exactly what I did to get the PCI card selected as default, but it was probably by specifying modprobe order in /etc/modules. And I couldn't recall the URL of the page where I found that solution. To top it all off, what works under Ubuntu/Debian ain't necessarily gonna work under Arch.
So, I began searching the web for solutions for this problem, favoring results that dealt with Arch. I found a few things that seemed to be relevant but, on careful reading, I found them confusing. I couldn't find any very specific directions to do what I was trying to do under Arch. Instead, I found various bits and pieces of information that seemed relevant but that needed to be put in some comprehensible form. So, I resorted to some fiddling around, hoping I would stumble on a solution. I think I have stumbled onto the solution to the problem of making one of two sound cards be the system's default sound card--at least it appears to be working now on my system. This post will therefore be an attempt to put the necessary information into order, providing a routine that others who may be faced with this task may follow.
The steps are as follows: 1) install alsa-utils; 2) as root, run alsaconf; 3) appropriately edit the file /etc/modprobe.d/sound that alsaconf created in step 3; 4) reboot to find the card you wanted to be the default sound card actually selected as the system's default. An important note: I didn't use alsaconf to do any sound card configuration, though that is its job. The only real role alsaconf played in the routine I used was to create the /etc/modprobe.d/sound file (it seems to create that file after you successully run the command alsaconf). Perhaps the file could be simply created de novo (sudo touch /etc/modprobe.d/sound , set permissions appropriately) and there would be no need to even run alsaconf. I didn't try that, but anyone following these instructions might want to consider doing it this way. Please post your results in this thread if you manually create that file rather than using alsaconf for creating the file.
After I ran alsaconf, the /etc/modprobe.d/sound file contained only two lines, and those lines were specific to the onboard sound chip that I did NOT want to be the default sound card on my system. The lines looked like this:
alias snd-card-0 snd-intel8x0
alias sound-slot-0 snd-intel8x0
From documentation I had read, I understood that the zero (0) in these entries was an indication that this onboard Intel sound card would be the default card. If the /etc/modprobe.d/sound file had contained entries for both my cards (not sure why it didn't), then one set of entries (referring the system's default sound card) would have a zero associated with them, while the other set of two entries (referring to the non-default, second sound card) would have had a one (1) associated with them.
With this information in mind, I then managed to get information from my system (by using lsmod, I believe) on what was the module name for my second, PCI card--the one I wanted to be the system's default sound card. The module name is snd_ymfpci. Once I had that information, I manually added a second set of two lines to /etc/modprobe.d/sound so that the file looked as follows:
alias snd-card-0 snd_ymfpci
alias sound-slot-0 snd_ymfpci
alias snd-card-1 snd-intel8x0
alias sound-slot-1 snd-intel8x0
As you can see, the entries for the snd_ymfpci have a zero associated with them, while the built-in intel sound card entries have a one (1) associated with them. I wasn't at all sure that this would bring the desired results but I found that, once I rebooted the system, that the add-in PCI card was actually now the default card for the system, while the intel onboard card was non-default. Thus, I believe I've stumbled on a solution for making the system use one of two sound cards on the system as the default sound card.
Please feel free to add to or correct my instructions. I can't claim infallible expertise in this matter, so there could well be mistakes in either my understanding or in the steps I've spelled out here. Or perhaps there's just a simpler way to do this under Arch.
James
Btw: I'm using the gnome environment. There seems to be a conflict, or at least some friction, between alsa's sound controls and those of the gnome desktop environment. It's a separate problem, but is there some way I can make gnome's sound controls (e.g., gnome's volume control) override alsa's? So far I've found myself using alsamixer to make any real adjustments to the sound.
Last edited by jamtat (2008-07-09 16:13:09)

Answer 1

I've written some post about it somewhere, but there's other ways of setting a default card. What I use at the moment (in XFCE):
The output of  cat /proc/asound/cards:
user ~  $   cat /proc/asound/cards
0 [CMI8738        ]: CMI8738-MC6 - C-Media CMI8738
                      C-Media CMI8738 (model 55) at 0x9c00, irq 17
1 [NVidia         ]: HDA-Intel - HDA NVidia
                      HDA NVidia at 0xfe020000 irq 20
2 [U0x46d0x8d7    ]: USB-Audio - USB Device 0x46d:0x8d7
                      USB Device 0x46d:0x8d7 at usb-0000:00:02.0-8, full speed
3 [default        ]: USB-Audio - USB Audio DAC   
                      Burr-Brown from TI               USB Audio DAC    at usb-0000:00:02.0-5, full s
I want to switch between sound-device "CMI8738" and "default" ("default" is a system label not set by me; it's a bit confusing but as you see the system has given the other USB-Audio device another unique label). You could also use the ID numbers, but the drawback of that is that it might change if you plug and unplug USB-Audio devices, hence the unique label is a better choice.
I choose to make a directory like this: /usr/sound. In sound I've to files, could be more if I wanted to switch between other cards as well. First file, named by me "asound_usb":
pcm.!default {
  type hw
  card default
  ctl.!default {
  type hw
  card default
Another named "asound_pci":
pcm.!default {
  type hw
  card CMI8738
  ctl.!default {
  type hw
  card CMI8738
The idea is to copy the preferred file to /etc/asound.conf. Hence I made two simple scripts in /bin. "alsa_usb":
#!/bin/sh
cp /usr/sound/asound_usb /etc/asound.conf && /etc/rc.d/alsa restart
And another "alsa_pci":
#!/bin/sh
cp /usr/sound/asound_pci /etc/asound.conf && /etc/rc.d/alsa restart
Writing in terminal from root "alsa_usb" or "alsa_pci" will switch default sound-device. Nothing fancy but pretty handy in my view. If someone prefer to have a desktop entry in /usr/share/applications you could use gksu for example. One I named "alsa_switch_usb.desktop":
[Desktop Entry]
Type=Application
Name=Alsa switch - USB
Comment=Eget skript
Icon=sonata-stock_volume-max.png
Exec=gksu -u root alsa_usb
Terminal=false
StartupNotify=false
Categories=Application;AudioVideo;
Another "alsa_switch_pci.desktop":
[Desktop Entry]
Type=Application
Name=Alsa switch - PCI
Comment=Eget skript
Icon=sonata-stock_volume-max.png
Exec=gksu -u root alsa_pci
Terminal=false
StartupNotify=false
Categories=Application;AudioVideo;
I don't know whether this is an ugly solution or not. Whatever the case is it works very well... for me. The asound.conf works of course as a permanent setting, I just prefer the switch option.
Last edited by KimTjik (2008-07-10 10:50:31)