[alsa-devel] Verifying mixer dB data/Invalid dB data from USB cards, especially Aureon 5.1 MkII
superquad.vortex2 at gmail.com
Fri Jun 25 00:51:21 CEST 2010
2010/2/16 Lennart Poettering <mznyfn at 0pointer.de>
> 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.
> Just run "make" in a git checkout and then try:
> $ ./dbverify Aureon51MkII Master 30 200
> That will verify the dB data of the "Master" control of the sound card
> that goes by the id "Aureon51MkII". It will compare the discrete
> volume steps 30 and 200: first it will play a full amplitude sine wave
> at mixer volume step 30, and then will change to mixer volume step
> 200, but attenuate the sine wave in software compensating for the
> volume change. So once you hear the sine wave attenuated by the hw,
> and once by the software. If the card's dB data is correct both sines
> should have the same volume.
Finally have time and an analog loop back cable to test your program
It really depend on your ear to do the verifcation which is not really
Unfortunately , I am unable to run dbmeasure on both of my au8830 and HDA
Can you provide any test result of your HDA sound card ?
!) The program dbmeasure.c seem underrun easily since you start the device
and waiting for the user to press enter key
2) it expect the sound driver can provide exactly 1 second buffer because
your logic is generate one second sample, Neither au8830 nor HDA driver can
provide exactly one second buffer
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