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[dsteinwe <1961998@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

I have tested the alsamixer with 2 different 8ch usb sound cards (UAC2
compatible) and the assignment of the volume controls to the respective
channel is partly wrong on both cards. The volume control for rear
changes the volume of the center and subwoofer/LFE and the volume
control for "Center" and "Woofer" changes the volume of the rear
speakers.

According to the usb audio class 2 specification, chapter "4.1 Audio Channel Cluster Descriptor", the volume controls index must be (for a 8ch sound card):
1 = FL
2 = FR
3 = C
4 = LFE
5 = RL
6 = RR
7 = SL
8 = SR

The current implementation as following assignment:
1 = FL
2 = FR
3 = RL
4 = RR
5 = C
6 = LFE
7 = SL
8 = SR

Unfortunately, I can not judge whether this is a problem in the program
or driver (audio usb).

If you have any questions, feel free to contact me.

** Affects: alsa-utils (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1961998

Title:
  alsamixer: volume controls are assigned to wrong channels

Status in alsa-utils package in Ubuntu:
  New

Bug description:
  I have tested the alsamixer with 2 different 8ch usb sound cards (UAC2
  compatible) and the assignment of the volume controls to the
  respective channel is partly wrong on both cards. The volume control
  for rear changes the volume of the center and subwoofer/LFE and the
  volume control for "Center" and "Woofer" changes the volume of the
  rear speakers.

  According to the usb audio class 2 specification, chapter "4.1 Audio Channel Cluster Descriptor", the volume controls index must be (for a 8ch sound card):
  1 = FL
  2 = FR
  3 = C
  4 = LFE
  5 = RL
  6 = RR
  7 = SL
  8 = SR

  The current implementation as following assignment:
  1 = FL
  2 = FR
  3 = RL
  4 = RR
  5 = C
  6 = LFE
  7 = SL
  8 = SR

  Unfortunately, I can not judge whether this is a problem in the
  program or driver (audio usb).

  If you have any questions, feel free to contact me.

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