[MPlayer-dev-eng] ALSA issue, r29549 fix seems incomplete

[Sylvain Bertrand]

> With dmix, the period size is fixed because all clients have to use the
> same value.

I do see that while running a mplayer a stereo dmixed stream (got a
periode=1024) if I start in parallel a new mplayer playing a 6 channel
dmixed stream, the latest get a periode of 1024 too.

>> and this takes you a bit over the 64 KiB per-call limit I mentioned
>> after all.
>
> Sylvain, as a quick fix, you could decrease the period size or time in
> your asound.conf.  The default dmix period size of 1024 frames would
> have worked; is there a reason why you changed it?

I did not. I use a stock alsa-lib 1.0.21a and my asound.conf basically
overrides surround51 with the following PCM chain
(plug->route->dmix->hw).
I had a look at the stock alsa.conf and see the following defaults settings:

defaults.pcm.dmix.max_periods 0
defaults.pcm.dmix.rate 48000

I checked the alsa pcm/dmix.conf and the defaults are periode
size=1024, periode time=-1,periods=16.

I had a quick look into alsa-lib git repo and I saw many changes in
the hardware configuration code.
In the mean time I'll enable some debugging code in alsa-lib about hw
configuration computations.

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