linuxaudio.org

Tim E. Real wrote:

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> 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

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> > 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.

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> 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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