Re: [LAU] Help with multichannel output

Le Fri, 6 Sep 2019 13:09:19 -0400,
Scott <scott.a.mayo@gmail.com> a écrit :

> You can probably guess my problem: on any reboot, the cheap USB
> devices, which don't have serial numbers, get randomly assigned to
> ALSA devices.

With a /etc/modprobe.d/alsa.conf file, you can reserve the ALSA
card slots for all the devices, start the computer and plug the USB
devices in the order you want them. Tested with 1 USB card here,
I think this should work with several USB devices.

Example:

# Alsa kernel modules' configuration file.

# ALSA portion
alias char-major-116 snd
# OSS/Free portion
alias char-major-14 soundcore

# Reserve first slot for snd-aloop
options snd slots=snd-aloop

## ALSA portion
alias snd-card-0 snd-aloop
alias snd-card-1 snd-hda-intel
alias snd-card-2 snd-hda-intel
alias snd-card-3 snd-virmidi
## OSS/Free portion
alias sound-slot-0 snd-aloop
alias sound-slot-1 snd-hda-intel
alias sound-slot-2 snd-hda-intel
alias sound-slot-3 snd-virmidi
#alias sound-slot-0 snd-card-0
#alias sound-slot-1 snd-card-1
#alias sound-slot-2 snd-card-2
#alias sound-slot-3 snd-card-3
##

options snd-aloop index=0
options snd-hda-intel index=1 model=alc271-dmic
options snd-hda-intel index=2
options snd-virmidi index=3

# OSS/Free portion - card #1
alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-8 snd-seq-oss
alias sound-service-0-12 snd-pcm-oss
## OSS/Free portion - card #2
alias sound-service-1-0 snd-mixer-oss
alias sound-service-1-3 snd-pcm-oss
alias sound-service-1-12 snd-pcm-oss
## OSS/Free portion - card #3
alias sound-service-2-0 snd-mixer-oss
alias sound-service-2-3 snd-pcm-oss
alias sound-service-2-12 snd-pcm-oss
## OSS/Free portion - card #4
alias sound-service-3-0 snd-mixer-oss
alias sound-service-3-3 snd-pcm-oss
alias sound-service-3-12 snd-pcm-oss

alias /dev/mixer snd-mixer-oss
alias /dev/dsp snd-pcm-oss
alias /dev/midi snd-seq-oss

# Set this to the correct number of cards.
options snd cards_limit=4

-- 
If you have a problem and you are not doing anything to fix it, you are
at the heart of the problem.
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