[alsa-devel] Verifying mixer dB data/Invalid dB data from USB cards, especially Aureon 5.1 MkII
perex at perex.cz
Tue Feb 16 11:36:55 CET 2010
On Tue, 16 Feb 2010, Jaroslav Kysela wrote:
> On Mon, 15 Feb 2010, Lennart Poettering wrote:
>> 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.
> 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:
I also updated the alsa-info.sh script to gather this information.
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.
More information about the Alsa-devel