[LAU] accessing hdsp mixer with amixer

[Andrew Gaydenko]

On Sunday 12 April 2009 01:10:09 you wrote:
> Andrew,
>
> > > > To have some reserve in volume I set amplifier's volume regulator
> > > > higher than, say, is needed at current moment. As a result I have
> > > > software level noticeably below 100%. I suppose such software volume
> > > > regulating eats samples resolution (and, at least theoretically,
> > > > sometimes I have, say, 12-13 bits rather 16).
> > >
> > > If you use the hdsp's matrix mixer, it will render the volume with
> > > higher precision than 16 bits, so play back unattenuated and control
> > > the output level in the matrix mixer.
> >
> > How to deal with the mixer (output channels) via CLI?
>
> amixer.
>
>
> Flo

Florian,

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?


Andrew


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