DirectSound, new patch available for testing

Davin McCall davmac at
Wed Nov 2 17:08:54 CST 2005

On Wed, 2 Nov 2005 14:02:55 +0000 (GMT)
Robbert Xerox <xerox_xerox2000 at> wrote:

> Hi Davin,Two questions about this:
> the patch fails here at hunk 5 with current cvs.

Works for me... I just made sure I had the latest files from CVS, but there have been no updates to these files since wine-0.9, apart from a small fix to mixer.c which wouldn't have caused a conflict even if you didn't have it.

Can you give me any more info? How are you applying the patch?

Does anyone else have this problem?

> 2nd question: is creating the key
> \HKEY_CURRENT_USER\Software\Wine\Alsa
> Driver\UseDirectHW
> necessary? If so, i'll have to do that manually (in
> regedit) i guess, as winecfg does not create such a
> key anywhere. And is this some undocumented key that
> also has 
> some effects without your patch? thanks in advance for
> your answer.

a) No, creating the key is not strictly necessary, but at this stage I'd recommend it

b) Yes, this is an undocumented key which also has some effects without my patch.

ALSA provides several type of device. Two of these are "hw" (direct hardware access) and "plughw" (a virtual device representing software layer which does sample rate and format conversion, before passing data on to the hardware).

The key lets you force a "hw" device to be used.

"hw" is the only one which gives you a try mmap'd hardware buffer. If a "plughw" device is used, you can still use ALSA calls to set up an mmap'd buffer but this will be an emulated mmap and as a result you either let latency get ridiculous or you try and feed the hw "just in time". My patch opts for the latter approach but there is a third option (using buffer locking) which I will implement at a later date.


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