Tim E. Real wrote:
> On July 27, 2010 01:00:31 am you wrote:
> > > Yikes! It's all coming back to me now, this can of worms.
> > > In my case the Delta101LT card has the AK4524 ADCs.
> > > The dB step of the IPGA stage is constant at 0.5dB, but the
> > > dB step of the DATT stage is not - anywhere from 6dB to 0.28dB !
> > > And remember the IPGA and DATT controls were combined, complicating
> > > things. Meanwhile, other AK chips' DATT stages are constant step.
The driver uses a volume lookup table to pretend that the mixer values
have constant 0.5 dB steps. This should be changed.
> > So does this mean 'alsamixer' has a bug for those card models with
> > combined IPGA? Which would that be?
> >
> > Note the code in 'alsamixer' which prints out dB-values -- is this
> > correct or not?
If there is a bug, it is in the TLV tables in the driver.
> Apparently there is a more advanced TLV based dB conversion.
> snd_tlv_convert_to_dB()
The snd_mixer_selem_get_*_dB functions just get the TLV table and then
call snd_tlv_convert_to_dB internally.
Regards,
Clemens
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Received on Tue Jul 27 12:15:02 2010
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