[Bug 30836] Total Overdose: choppy audio playback with Diesel Power 3D sound system

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=30836

Jörg Höhle <hoehle at users.sourceforge.net> changed:

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--- Comment #13 from Jörg Höhle <hoehle at users.sourceforge.net> 2012-10-24 16:27:16 CDT ---
Andrew, seeing this bug I understand why you'd like to get that other patch
into Wine.  Yet it's unclear to me what exactly makes it work: your patch does
2 things, the rate limiting and some changes to ALSA buffer sizes and periods. 
I mean, it could work by side-effect rather than due to actual rate limiting.

Your analysis appears very plausible.

>It sometimes takes more than a period for the ALSA driver to
>update its IAudioClient::GetCurrentPadding().
"sometimes" because of jitter or why?
Or because the ALSA buffer may be filled with the effect that
mmdevapi:GetCurrentPadding may not decrease for 2-3 mmdevapi periods or at
least one ALSA period (which could be as much as 100ms)?
In that case, we should conclude that it's a bug for mmdevapi:GetCurrentPadding
not to decrease as regularly as native's.  My point is that there can be
solutions to this independently of rate-limiting, e.g. I imagine a driver that
decrements padding exactly once per event by one period worth of frames and
adapts its event rate to +/- 20% actual drain by the underlying ALSA driver.

DSound should be somewhat independent on mmdevapi.  All apps named here do not
see mmdevapi directly rather than DSound.  So it's clearly a bug of DSound's
GetCurrentPosition not to change as regularly as the "Direct HW ping pong
buffer" abstraction would suggest.  That might be tackled independently on
mmdevapi.

The (unsurprising) lesson is: it's not enough to satisfy the API.  The apps
very much depend on comparable dynamic behaviour.

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