[alsa-devel] Verifying mixer dB data/Invalid dB data from USB cards, especially Aureon 5.1 MkII

[Jaroslav Kysela]

On Tue, 16 Feb 2010, Jaroslav Kysela wrote:

> On Mon, 15 Feb 2010, Lennart Poettering wrote:
>
>> Heya,
>> 
>> a while back I wrote a little tool "dbmeasure" which can be used to
>> determine dB attenuation data for alsa mixer controls. I have now
>> extended this little dB tools suite to include a tiny tool "dbverify"
>> that can be used to verify the correctness of existing dB data exposed
>> by the drivers. It should be relatively easy to use that tool,
>> suitable even for non-guru folks who want to debug the dB information
>> from alsa.
>> 
>> http://git.0pointer.de/?p=dbmeasure.git
>> git://git.0pointer.de/dbmeasure.git
>
> Thank you for this code. I'm playing with an idea to start gathering of all 
> ALSA tests around and make a GUI for them. But it might make sense to use 
> something more portable than C language and use standard ALSA tools (amixer, 
> aplay) as backends ;-)
>
> For USB cards, the dB ranges read from hw are not correct. We have to 
> overwrite these bad values in the driver. Unfortunately, the USB driver 
> doesn't show the USB descriptor -> ALSA control mapping to gather all 
> necessary information for the code updates. I'm working on a patch right now 
> to obtain this information using procfs.

The patch is available here:

http://git.alsa-project.org/?p=alsa-kernel.git;a=commitdiff;h=6daf48108cb0136b762998bb5c2b0b32234b4e93

I also updated the alsa-info.sh script to gather this information.

 						Jaroslav

-----
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.