[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 #69 from Jörg Höhle <hoehle at users.sourceforge.net> 2011-12-03 14:28:02 CST ---
>isn't the only reason to add the silence is to workaround the "pcm is not
>starting unless at least one [ALSA] period of data had been pumped out"?
I now see three. 1 help start up;
2. trailing samples not heard, comment #63;
3. play 100Hz beeps when app fills 5ms at every 10ms event, comment #55.

>Taking into account silent frames [...] is pretty simple.
With either lead-in or trailing only silence, not in the 100Hz scenario.

>How the things actually are can only be determined by reverse-engineering
How can you conclude this? Look at how much we've found out simply by printing
GetPosition & GetCurrentPadding and writing tests. Writing tests teaches a lot.
Have a look at the blackbox game inside Emacs. Type Esc-x blackbox Return and
^H f blackbox Return. Or google the file "blackbox.el" and read the
documentation string inside the Lisp stuff :-)

Back to bugs, one can derive the requirement
set_hw_params_period_max 20ms
based your appDB comment when one uses my pseudo code from comment #58 given
ALSA's insistence on being fed a full period before doing anything. 10ms
lead-in and 10ms prefill will then ensure ALSA starts.  However, 20ms is too
large for sustained sound as it means that ALSA is fed a full 20ms period only
around the time of ALSA underrun. Rage's scenario really needs
set_hw_params_period_time_max 10ms
to work reliably -- unless latency is artificially increased (by maintaining
GetCurrentPadding e.g. 50ms lower than required using a silence lead of same
size).  The device could even adapt dynamically and reduce the period from e.g.
100ms downto 10ms should an underrun occur. Daydreaming?

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