[alsa-devel] C-Media USB Audio Device (0d8c:000c) volume scale

[Alexander Schlarb]

Hi everybody!

I've just opened what I think is a bug at GitHub[1] and have been told to send 
it to this list instead.

System configuration:
 - http://www.alsa-project.org/db/?f=fb914e7a6b8d91993b00d61c94c885e8d2ede527
 - https://github.com/opensrc/alsa/issues/4 (some additional PulseAudio stuff)

My problem:
I have a DeLock USB audio device with an C-Media audio chip. When changing the 
volume in alsamixer there is no problem, but when changing the volume through 
any PulseAudio frontend (in my case either pavucontrol or veromix-plasmoid), 
all volumes below 30% in the GUI are shown as 0% in alsamixer and no sound is 
played.
The PulseAudio wiki[2] blames this on ALSA for exporting incorrect dB 
information. However there is a StackExchange answer[3] which suggests adding 
the parameter ignore_dB=1 in /etc/pulse/default.pa which fixed the issue, so 
I'm not sure if this is indeed ALSAs fault?

Please tell me if this can be fixed in ALSA or if this might be a PulseAudio 
bug...

With best regards,
Alexander Schlarb

[1] https://github.com/opensrc/alsa/issues/4
[2] 
http://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/PulseAudioStoleMyVolumes/#butthisisevilmypcmcontrolisalwayssetto100thisway
[3] http://askubuntu.com/questions/15069/how-do-i-change-the-way-ubuntu-adjusts-my-volume-mixer-levels
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