Pulseaudio enables Surround 4.0, while chmap reports no RL and RR
Submitted by Arthur Borsboom
Assigned to pul..@..op.org
Description
In an effort to get an external subwoofer and a headset to work on my Asus N751JK laptop, I have started working with the Alsa devs.
After applying an Alsa patch to the Linux mainline kernel v4.2.0-rc3, an alsa developer believes one of the issues is a bug in Pulseaudio, see his statement at the end of this conversation: http://permalink.gmane.org/gmane.linux.alsa.devel/141974
Here is the whole conversation: http://comments.gmane.org/gmane.linux.alsa.devel/140852
Apparently on my laptop the Alsa-lib test tool 'chmap' shows the following channels:
Type = FIXED, Channels = 2 FL FR Type = FIXED, Channels = 4 FL FR NA LFE
Pulseaudio (or pavucontrol) shows Stereo, Surround 2.1 and Surround 4.0. However, according to the alsa dev the Surround 4.0 option should not be there since there are no Rear Left and Rear Right speakers.
Alsa-info: http://www.alsa-project.org/db/?f=ab56d544c53402fc7fdb96956299753de2708a6f
Pulseaudio verbose log: http://pastebin.com/MwC3KQS5
How would you suggest to analyze and/or fix this issue?