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

Jaroslav Kysela perex at perex.cz
Sat Feb 20 09:38:12 CET 2010

On Fri, 19 Feb 2010, Raymond Yau wrote:

> 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 )

This API is not implemented at the time.


Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.

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