[pulseaudio-discuss] [PATCH] Change the default fragment size to 5 ms

[Andrew Eikum]

On Thu, Oct 23, 2014 at 10:57:18PM +0530, Arun Raghavan wrote:
> On 23 October 2014 22:46, Alexander E. Patrakov <patrakov at gmail.com> wrote:
> > 22.10.2014 22:21, I wrote:
> >>
> >> Of course, this only applies to ALSA devices that can't use tsched, as
> >> well as to OSS on more exotic platforms.
> >>
> >> This is needed for compatibility with Wine games that use DirectSound8
> >> on distributions such as Arch Linux who don't accept the unofficial
> >> winepulse patch. The reason is that Wine DirectSound8 emulation requests
> >> a period of 10 ms and expects it to work for the purposes of timing. And
> >> in fact, it cannot know (via ALSA API) that it is not going to work!
> >
> >
> > I hereby withdraw the patch, as on IRC I see that Arun said:
> >
> > """
> > I'm not too happy with changing that. It would affect CPU on systems that
> > don't care about Wine.
> > and I really really don't want to work around bad clients in PA. (despite
> > the fact that I am also bitten by this bug)
> > ...
> > Want to start a BrokenClients page?
> > """
> >

It's true that Wine's audio doesn't get much work these days, though
in my defense :) it's a time issue, not a willingness issue.

I have spent literally weeks trying to understand and work around the
timing issues that cause problems with USB devices accessed with the
PulseAudio ALSA plugin. I plan to continue working on it, but business
priorities lay elsewhere at the moment and I've already spent loads of
time on it.

> > (note: due to the "cannot know" reason, I still disagree that it is a
> > client-side problem)
> 
> I've not looked at the Wine code for this, but I wonder if we can
> guess this by looking at the minreq/tlength values that are returned.
> 

I'd love to work with an ALSA/PA expert to come up with a solution,
either by fixing Wine or coming up with a new ALSA API to provide the
info we need.

I have a patch in-hand which improves the current driver
significantly, but it isn't enough to fix the USB devices problem. If
someone wants to review the winealsa driver with the patch applied and
discuss solutions, let me know. I'd love to get this problem solved.

Andrew