ubuntu-22.04.3-desktop-amd64/casper/filesystem/usr/share/alsa/ucm2

Use Case Configuration files

Library directories:

platforms/ codecs/ dsps/

Those directories are not inspected for the list of available UCM configurations. They contain files included from other UCMs.

UCM master configuration path lookup is defined in the top level ucm.conf file. This file allows custom directory layout. The new ucm2 layout is based on the ALSA driver name with the kernel driver name as fallback. The virtual cards (no direct hw bound) lookups are placed to the separate conf.virt.d directory.

The lookup configuration:

https://git.alsa-project.org/?p=alsa-ucm-conf.git;a=blob;f=ucm2/ucm.conf

Example paths - new conf.d scheme:

• conf.d/USB-Audio/Dell-WD15-Dock.conf -- special configuration for the Dell docking station with USB soundcard
• conf.virt.d/TwoCardsMix.conf -- virtual UCM from two soundcards

Example paths - no conf.d scheme (may be invalidated):

• USB-Audio/Dell-WD15-Dock.conf -- special configuration for the Dell docking station with USB soundcard
• TwoCardsMix/TwoCardsMix.conf -- virtual UCM from two soundcards

Note: For the driver configurations, use always the ALSA driver name or the real kernel driver name - not the ucm card name configuration paths!

The kernel driver name is obtained using sysfs like (last part of the path is used from the symlink):

  /sys/class/sound/card0/device/driver

The ALSA driver name can be obtained using procfs like:

  cat /proc/asound/cards
  1 [NVidia         ]: HDA-Intel - HDA NVidia
                       HDA NVidia at 0xb5080000 irq 17

  driver name: HDA-Intel
  card short name: HDA NVidia
  card long name: HDA NVidia at 0xb5080000 irq 17

Syntax, value names

https://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=include/use-case.h