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SubjectRe: OSS sound emulation broken between 2.6.0-test2 and test3
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On Sat, 2003-12-27 at 14:33, Martin Schlemmer wrote:
> On Sat, 2003-12-27 at 15:08, Edward Tandi wrote:
> > On Sat, 2003-12-27 at 12:24, Martin Schlemmer wrote:
> > > On Sat, 2003-12-27 at 13:44, Edward Tandi wrote:
> > > > On Sat, 2003-12-27 at 11:11, Martin Schlemmer wrote:
> > > > > On Sat, 2003-12-27 at 09:50, Martin J. Bligh wrote:
> > > > > > Something appears to have broken OSS sound emulation between
> > > > > > test2 and test3. Best I can tell (despite the appearance of the BK logs),
> > > > > > that included ALSA updates 0.9.5 and 0.9.6. Hopefully someone who
> > > > > > understands the sound architecture better than I can fix this?
> > > > > >
> > > > >
> > > > > I wont say I understand it, but a quick look seems the major change is
> > > > > the addition of the 'whole-frag' and 'no-silence' opts. You might try
> > > > > the following to revert what 'no-silence' change at least does:
> > > > >
> > > > > --
> > > > > # echo 'xmms 0 0 no-silence' > /proc/asound/card0/pcm0p/oss
> > > > > # echo 'xmms 0 0 whole-frag' > /proc/asound/card0/pcm0p/oss
> > > > > --
> > > >
> > > > Thanks, that fixes it for me. I too have been seeing terrible problems
> > > > with XMMS since the early 2.6 pre- kernels.
> > > >
> > > > Because it only happens in XMMS I thought it was one of those
> > > > application bugs brought out by scheduler changes. I now use Zinf BTW
> > > > -It's better for large music collections (although not as stable or
> > > > flash).
> > > >
> > >
> > > Can you check which one actually fixes it ?
> >
> > Yes, its the 'whole-frag' line.
> >
>
> Well, I can't say I can see why. In snd_pcm_oss_write1 where the change
> for whole-frag was, I cannot see a race or such. The only possible
> causes I can see, is that:
> 1) xmms's scheduling gets screwed due to the short writes
> 2) some drivers may have issues with getting short writes all the time.
>
> Only problem with 2), is that Zinf works fine for you, so I guess the
> only thing to assume is that either Zinf do not use OSS, but ALSA
> interface, or that 1) is indeed the correct answer. What version of
> XMMS do you use btw?

I was originally running 1.2.7 when I first encountered the problem. I
then built 1.2.8 -but no difference.

Zinf does indeed use the ALSA interface (as most apps do nowadays).

I would say the symptoms are that the music starts playing OK bit after
a short period (18-19 seconds), the music changes overall speed (by a
semi-tone or so). When it does this, the sound also starts to break up.
This is why I associated the problem with the process scheduling changes
being made at the time.

It could be a driver issue. FYI, I am using a VIA KT400 chipset. Any one
know of any low-level timing issues with the KT400?

Ed-T.


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