[alsa-devel] Latency of mixer reconfiguration

[Lennart Poettering]

On Fri, 19.02.10 09:54, Mark Brown (broonie at opensource.wolfsonmicro.com) wrote:

> > > I suspect that trying to offer additional resolution in this way is more
> > > trouble than it's worth if you're concerned about the artifacts that are
> > > introduced during updates.  Providing per-channel differentiation if the
> > > hardware has only mono control has much fewer problems, though.
> 
> > The current logic is to not do any software adjustment if the hardware
> > adjustment is "close enough" to the total adjustment we want to do,
> > tested against a threshold. Which I think is quite a reasonable
> > approach because it enables/disables this feature not globally, but
> > looks at each case and enables this logic only if it really has a
> > benefit.
> 
> That sounds reasonable, though it's kind of surprising to me that there
> is hardware out there which benefits from it - I'd have expected either
> adequate resolution or nothing at all there.

On my own hardware this mechanism proved useful in two cases: one card
had a single volume slider for both channels and with PA you can now
set their volume independantly. And one set of external USB speakers
has a volume slider that starts at a very high level, so that the
minimum volume setting is everything but silent. PA extends the scale
downwards so that this limitation of the hw does not become apparent.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4