[MPlayer-users] "buggy sound card driver"

[Florin Andrei]

Quoting thomas.seeley at ntlworld.com:

> In the docs and again here:
> 
> http://www.mplayerhq.hu/pipermail/mplayer-users/2002-May/015950.html
> 
> Jerky video problems which go away when -nosound is used are blamed
> on the sound card driver.
> 
> I have no specific problem with this diagnosis, I'd just like some
> additional information which I can present to the alsa dev. team. 
> (ie something that would help them fix the problem.)
> 
> FYI, I'm using a fm801 (fortemedia) based card.

Yes, please bug them a little bit. I have the same feeling: there's a
tiny bug that's triggered rarely and, as a result, generates jumpy video.

Here's my experience:
I have an AthlonXP on an nForce motherboard (manufactured by MCI,
includes an nVidia nForce chipset that does everything, including
sound). I use the nVidia "official" drivers for nForce and, on top of
that, ALSA-0.9.0rc3 built by myself.

With Red Hat 7.3, everything was perfect, i had no problems whatsoever.
Playing was smooth with any player i've tried: Mplayer, Xine, Avidemux
in preview mode; with the first two i used the ALSA native output, with
the last one i used the OSS emulation in ALSA (Avidemux doesn't speak
native ALSA, i believe).

After upgrading to Red Hat 8.0, i started to notice problems with
Mplayer and Xine. When booting up the system, everything was fine. But
after a day or so, the video got jumpy, Xine started to drop like 1
frame every 200 frames (and probably Mplayer did that too), i even heard
noticeable hiccups in the sound.
Using the OSS emulation in the players usually fixed the problem, but
not always.
Restarting the ALSA subsystem (mute the output, unload the modules, load
the modules, re-apply mixer settings) proved to be a much better fix
(although a temporary one, because after a while the symptoms return).

Someone told me that overlapping interrupts may cause such problems, and
sure thing - the interrupts on my system are badly overlapped (several
devices share the same interrupt).
I'll try to move interrupts around and see what happens, because it's a
reasonable thing to do anyway (especially if you want your system to be
as fast as possible). However, even if that would fix the symptoms (i
didn't tried yet), it still does not explain two things:
- why it worked fine with Red Hat 7.3
- why reloading ALSA makes the problem disappear temporarily

I'll also try ALSA-0.9.0rc5, because they mention a "gcc-3.2 fix" in the
ChangeLog.

On a different system, a PIII on a cheap motherboard, running Red Hat
7.2, i didn't had any problems with ALSA no matter what.

-- 
Florin Andrei

http://florin.myip.org/

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