[RFC/RFH] winmm:wave hang fix question (commit 717df5b2972b3cb998ca5a43279ae2283b117eaa) [bug 15559]

[Reece Dunn]

2008/11/21 Chris Robinson <chris.kcat at gmail.com>:
> On Friday 21 November 2008 10:26:19 am Reece Dunn wrote:
>> I want to submit the following patch to revert the part of the patch
>> that caused the regression and fix some of the tracing. I have been
>> using this patch on Cepstral SwiftTalker without issue and have tested
>> it also with the game Azguard Defense.
>>
>> I am submitting this here and not to wine-patches initially, as I
>> would like to understand what the fix was actually fixing and (based
>> on the test history still showing timeouts) whether it actually fixes
>> the issue it was trying to.
>
> Hi Reese,
>
> As far as I understand, the issue is that winealsa uses the delay value to
> determine how much data is unplayed in the pcm buffer, and it expects the
> delay to be 0 when it's empty. The problem is, snd_pcm_delay measures the
> time it would take for the next sample written to get through the DAC, which
> is only marginally related, and may not get down to 0 (depending on the
> backend, there may always be some delay even if the next samples written get
> played right away).
>
> The proper way to fix this, AFAIK from the conclusion on IRC, would be to
> subtract the snd_pcm_avail_update() value from the total pcm buffer size, as
> a way to determine how much is unplayed in the buffer instead of abusing
> snd_pcm_delay.

Thanks for the info.

I will have a stab at implementing this and then submit a patch.

Thanks,
- Reece