winealsa: improve sound quality for IDsDriverImpl

[Robert Reif]

Here is the patch that addresses the 8 bit mixer problem.  I just
cut it out of an old development tree that had a lot of other mixer
changes so I doubt it will apply cleanly but it will give you an idea
of the problem.

This patch and the tests developed for it uncovered the locking
issues which I have not fixed yet.  I hope to submit a real fix for
all this someday but I hope this partial fix can be of some use
until then.

Robert Reif wrote:

> There is a bug in the mixer code that doesn't clear the primary
> buffer to a proper silence value for 8 bit hardware buffers.
> I have a patch that fixes this that I have been sitting on for months
> now.  The problem is that there are locking problems in the
> SetFormat code for primary buffers that cause it to crash immediately
> for the tests I have written to exercise it.  I have added some more
> locking to try to fix it and it is much better but it's not 100% yet.
> It would probably be ok on a single processor system but still has
> SMP issues.
>
> Jerry Jenkins wrote:
>
> > > sox -c1 -r44100 -sw /usr/share/sounds/pop.wav -tossdsp /dev/audio &&
> > > wine winamp
> > >
> > > has the problem, but
> > >
> > > sox -c1 -r44100 -sb /usr/share/sounds/pop.wav -tossdsp /dev/audio &&
> > > wine winamp
> > >
> > > is unbelievably good. How could it be? I should find out if it's
> > > something is wrong with my system or something else.
> > >
> > Only one of my sound cards suffers from the problem when the format of
> > primary buffer is 22050 samples per second, 8-bit stereo. The other is
> > OK. It appears to be a big challenge for me. And I am a little curious
> > about how many peoples would have such experience.
> > I submitted a new patch, please test it.
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