Re: [LAU] accessing hdsp mixer with amixer

On Sun, Apr 12, 2009 at 9:47 AM, Paul Davis <paul@email-addr-hidden> wrote:
> On Sat, Apr 11, 2009 at 8:16 PM, Andrew Gaydenko <a@email-addr-hidden> wrote:
>>
>> Yes, I see amixer must be used. The proble is, hdsp driver maps card's mixer
>> controls to alsa mixer controls in not-obvious way.There was somewhere some
>> information about accessing hdsp mixer controls (how to relate channels and
>> appropriate controls, write (and read?) values and such), but I can not found
>> it now (probably it was at old alsa site).
>>
>> The card has
>>
>> numid=5,iface=HWDEP,name='Mixer'
>>
>> control, and, probably, something like
>>
>> amixer cset numid=5 x,y,z
>>
>> must be used. What are those x, y, z? :-)
>>
>> OTOH, it seems like I can not get current hdsp mixer settings: 'amixer cget
>> numid=5' just returns a tuple with three zero rather full 3dim matrix. Can I?
>>
>> Has anybody elaborated information about all these issues?
>
> don't quote me on this but i have a recollection that access to the
> matrix mixer via the ALSA standard mixer API was removed. notice that
> the IFACE above is "hwdep", and i don't think that amixer can be used
> to control this.
>
> i may be utterly, totally wrong on this. and the sad thing is that i
> should know :(
>
> --p
>

I was going to say the same thing yesterday but my recollections on
this are so very vague I kept my mouth shut for once. ;-)

If I remember correctly Thomas removed them on purpose as the HDSP
family has so many outputs and there's no way to know what a given
user is using to get to his mains. (I use 23/24 & 25/26 as my main
outputs for instance) IIRC we had conversations about letting Alsa
control volumes but worried that maybe it would drive levels on an
output that could hurt some piece of equipment. If Alsa tried to
manage the router then it would have to recreate most everything in
hdspmixer therefore just use hdspmixer.

In the end it was Thomas that decided what to do.

In my case I use the on-board sound chip as the device that Alsa uses
by default. I take that physical output and route it back into an HDSP
input and then mix its level in hdspmixer. I only really use the HDSP
software ins and outs for Jack audio. All system audio just comes into
the HDSP, is routed and then back out to my mains.

- Mark
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Received on Sun Apr 12 20:15:03 2009