Re: mplayer + heavy io: why ionice doesn't help?

[Denis Vlasenko <vda.linux@googlemail.com>]

On Sunday 20 August 2006 16:43, Lee Revell wrote:
> On Sun, 2006-08-20 at 10:22 +0200, Jan Engelhardt wrote:
> > >
> > >It helps. mplayer skips much less, but still some skipping is present.
> > 
> > Try with -ao alsa, then it should skip less, or at least, if it skip, skip 
> > back so that less audio is lost.
> > When playing audio-only files, it is always wise to specify e.g. -cache 320
> > which proved to be a good value for my workloads.
> > 
> 
> Only with the very latest versions of mplayer does ALSA work at all.
> It's unusable here because it resets the auduio stream on each underrun
> rather than simply ignoring them.

I'm not sure that I ever got an underrun (may check it
for you if you need that, how to do it?),
but mplayer -ao alsa is working for me just fine.

I eliminated skips due to CPU and disk using
nice and -cache 8000. I still can make it skip
when my KDE background picture is changing.

I think that these skips are caused by the X server.
It has no prioritization for request handling and
thus it does not paint mplayer output fast enough:
it needs to repaint background and semi-transparent
konsole(s), and that is taking a few seconds at least.

This is probably aggravated by serializing nature of Xlib,
according to:

http://en.wikipedia.org/wiki/XLib
http://en.wikipedia.org/wiki/XCB
--
vda