[pyddr-discuss] Juddery arrows

[Joe Wreschnig]

On Mon, 2004-07-26 at 18:21, Dave Wilson wrote:
> Hi all,
> 
> I'm using pydance under debian testing, and while it all works - and for the 
> most part pretty smoothly - there is a regular judder to the arrows. They 
> scroll perfectly smoothly for maybe half a second, then stop for a split 
> second before resuming.
> 
> I'm not sure where to go with this, as it's clearly not plain CPU-bound 
> performance problems. I'm using kernel 2.6.7, pydance 1.0.2, xfree-4.3.0, 
> python-2.3.4 and psyco 1.2. The video card is an NVidia-based Abit Siluro 
> Geforce MX 200. I've tried 24 and 16 bit colour.

It's not CPU-bound in the traditional sense, no. Let me guess -- you've
got an onboard sound card? Probably an Intel i8x0 AC97 variant? I've
seen this on several systems (across different platforms, and even
different dancing games), and that's the only thing they've all had in
common.

My theory is, that as the games eat 100% CPU time (to process events as
accurately and as fast as possible), the sound card gets starved since
the cheap onboard soundcards rely on the CPU to do more data pushing.

If that's the case, I don't know of a way to fix it, beyond buying a new
sound card. I also don't know of a way to verify this beyond hacking
around in the sound drivers, which I really don't want to do. If you're
using still OSS instead of ALSA, you might want to switch; my experience
is that ALSA has less of a problem than OSS.

David Dodge's suggestions are also possible, but I think this is the
much more common case.
-- 
Joe Wreschnig <piman at debian.org>
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