Aaron Slunt wrote:
Jan Zerebecki wrote:
On Sun, Sep 17, 2006 at 05:26:12PM +0100, James Courtier-Dutton wrote:
I am an ALSA developer, and at one point tried to fix the wine alsa
support. I found the wine source code very difficult to read and
understand. Windows seems to have so many different sound APIs, I
did not really know where to start.
Everything in wine that uses alsa is below dlls/winmm/winealsa/.
I explained in a different mail to this thread what bugs are in
winealsa. (Archive link to that mail is:
http://www.winehq.org/pipermail/wine-devel/2006-September/050826.html )
I suspect that either wine will have to change a lot, or ALSA will
have to change a lot before they work nicely together.
As explained in the mail refrenced above the main problem is that
in wine the alsa callback signal (that we currently use) won't
work properly without special care, but the fd based method (for
example with select) should work as expected. We just need
someone to code this change.
It seems I just found out how to fix the other winealsa problem I
mentioned in that mail, I'm currently testing if it works.
Jan
Jan, could you please clarify what you mean by an fd-based method?
Thanks.
I have not looked at the wine source code lately, but I would advise you
that it would be sensible to talk to the sound card at only the 48000 Hz
rate.
If a windows application wants 44.1kHz, I would suggest that you add
your own resampling code to wine.
The reason for this is that a Linux application can ask for some buffer
size from the alsa-lib. If the sound card hardware cannot do that buffer
size in hardware, alsa-lib will reject the request and leave it to the
application to try a different value. This is all ok for an open source
application, as one can just fix the application to act accordingly.
This is not the case with a binary application like all the applications
running on top of wine. One cannot fix those applications to work nicely
with alsa-lib. As a majority of sound card hardware works nicely at
48kHz, but very few sound cards do 44.1kHz in hardware, the application
must then do the resampling necessary to achieve the task. alsa-lib does
do resampling currently, but it has some importance constraints that I
think are incompatible with wine. I would therefore recommend that wine
does it's own resampling to 48kHz before passing sound to alsa-lib.
In time alsa will remove the resampling constraints present in alsa-lib,
but that fix is not expected any time soon.
As most windows applications running on wine tend to use the 44.1kHz
rate, that will cause problems with the current alsa-lib. So, if wine
want windows games to work better with sound when using alsa-lib, I
would recommend wine doing the resampling.
James
