[Bug 28723] Sound stutter in Rage when emulated windows version is set to "Windows 7" (XAudio2 -> mmdevapi sound output path)

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=28723

--- Comment #128 from Jörg Höhle <hoehle at users.sourceforge.net> 2012-02-04 02:45:08 CST ---
Well, I've a simple explanation for the crackling sound that my audible
worst_case/Xaudio2 test attached to bug #27937 produces. I always thought it
would explain stuttering (as in the subject line of this bug) but I perceive it
as crackling instead (as in the subject line of bug #28856).

If my test_worst case really replicates XAudio2 behaviour, that would explain
crackling in all apps that use XAudio2 (i.e. w7 xact audio insead of xp
DSound).

Case 1:
render.c:Released 48000=100x480 -480 frames at 48000 worth 990ms in 1196ms
Here CreateEventTimer delivers events every 12ms -- always late.  As
test_worst_case never writes more than one (10ms) period, audio hits an
underrun every few periods.  This cause a crackling sound partly covering the
sine tone. Crackling is almost continuous.

Case 2:
render.c:Released 48000=100x480 -480 frames at 48000 worth 990ms in 1009ms
On this machine, CreateEventTimer delivers events every 10ms like we asked. 
However, because event delivery is not synchronized to the audio clock, there
may be times where GetCurrentPadding is larger than one period.  Every such
time, test_worst_case won't write data. There will be a hole, resulting in an
underrun and crackling some timer later.

Case 3:
render.c:Released 40320=84x480 -960 frames at 48000 worth 820ms in 789ms
Here I cheated on the 12ms timer machine, using CreateTimerQueue(period_ms -3),
resulting in timer callbacks 8ms apart. In that case, not writing a period full
of samples was not harmful, as it would likely be written at the next timer
event. That's why only 84 periods were written in that case, despite receiving
100 events. The result is a continuous sine, without crackling.

I consider the algorithm "write one period if padding is less or equal to one
period" to be stupid, because it doesn' take clock skew into account. Or it
hints that native's doesn't deliver events like we do.

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