Re: Surround sound and volume control question

[Daniel Jacobowitz <drow@false.org>]

On Mon, Oct 09, 2006 at 10:42:56AM -0400, Lee Revell wrote:
> On Mon, 2006-10-09 at 10:38 -0400, Daniel Jacobowitz wrote:
> > I did consider doing it this way over the weekend.  However, being
> > able to adjust the relative volumes of the different channels still
> > seems useful to me.  If you have a single unified control, then you
> > mess up trying to move the others.
> > 
> > What do you think?  Should I just slave them all together and remove
> > the other volume controls?  It's probably easier; it just seems
> > somehow lacking.
> > 
> 
> How do other OSes do it?  Do they also force everything through a
> software volume control?

Unfortunately, I could find a program to dump the ice1724's IO space in
Windows, but I couldn't find anything to dump the vt1617a AC97
registers (which require writes to select the registers IIRC).  If
you've got a recommendation, I can boot this machine into Windows and
see what happens to the vt1617a's registers when the Windows driver
adjusts the volume.

> Is a ganged master control fundamentally incompatible with individual
> channel volumes?  If so, doesn't it mean that this problem can never be
> solved by an abstract mixer layer?

I don't know.  I guess you could preserve individual channel volumes by
saving them separately (outside the registers), and using a volume of
"master control plus channel control".  But I don't know how the
resulting quality would be or how tricky it would be to implement.
Right now we never cache the volumes corresponding to hardware
registers.

-- 
Daniel Jacobowitz
CodeSourcery

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