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Naming multiple alsa sound cards

Newsgroups:  gmane.linux.debian.user
Date:        Thu, 3 Aug 2006 16:21:01 +0200

> For the alsa behaved apps (like libao) you set alsa_card=1 or 0 and
> ao_example.c plays on either one soundcard or the other.

Just a small tip. On machines with multiple sound devices the alsa card numbers may not be predictable because the device number depends on which card was detected first. On my machine it seems to be pretty random. Alsa allows you to refer to sound devices by *name* though too, which works much more predictably. So for example in libao you would use the driver option "dev=hw:NAME" instead of "dev=hw:NUMBER". The names of the devices on your machine are listed (in square brackets) in /proc/asound/cards.

CJ van den Berg

Naming multiple alsa sound cards

> random. Alsa allows you to refer to sound devices by *name* though too,
> which works much more predictably. So for example in libao you would use
> the driver option "dev=hw:NAME" instead of "dev=hw:NUMBER". ...

one of the things that udev affects is device names. there have been issues with various devices having seemingly random names because of udev rules not being setup. The most notable has been eth naming but I would expect sound devices to be affected by the same issue thus look into udev configuration as a way to address this. cheers,

Kevin Mark

Naming multiple alsa sound cards

> Just a small tip. On machines with multiple sound devices the alsa card
> numbers may not be predictable [...]

I have this in /etc/modprobe.d/sound:

alias snd-card-0 snd-via82xx
options snd-via82xx index=0
alias snd-card-1 snd_ca0106
options snd_ca0106 index=1

and now the cards always seem to come up in that order. But thanks for the tip!

Hugo Vanwoerkom