[alsa-devel] Verifying mixer dB data/Invalid dB data from USB cards, especially Aureon 5.1 MkII

Raymond Yau superquad.vortex2 at gmail.com
Fri Feb 19 11:57:36 CET 2010

2010/2/19 Jaroslav Kysela <perex at perex.cz>

> On Thu, 18 Feb 2010, Lennart Poettering wrote:
> >> For the Mic Boost +20dB case , how PA handle this +20dB switch in the
> "Flat
> >> Volume" model if you did not expost the Mic Boost switch to the user in
> the
> >> mixer control ?
> >>
> >> +20dB is quite significant in with the Capture Volume control
> >
> > We currently don't cover boost switches, simply because tehre is no dB
> > data queriable for them.
> >
> > I'd really prefer if those boost switches would be turned into binary
> > volume elements which carry normal dB information like any other
> > volume element. After all they are just a volume element, with only
> > two steps.
> I like this idea.
>                                Jaroslav
PA assume every sound card can only record from one capture source at the
same time (like those AC97 card )

However HDA support multi streaming capture , the capture device 0 may have
more than one subdevice "Capture sources"  depend on the codec and  device
2  has 2 subdevice for capturing "Input sources" on some codec

Is HDA_SUBDEV_NID_FLAG or any API for the application to find the correct
mixer control for these kind of capturing subdevices  ? ( simple mixer api
is not able to know the subdevice number )

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