[alsa-devel] Verifying mixer dB data/Invalid dB data from USB cards, especially Aureon 5.1 MkII
perex at perex.cz
Tue Feb 16 09:32:50 CET 2010
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.
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.
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