[prev in list] [next in list] [prev in thread] [next in thread] 

List:       kde-multimedia
Subject:    Re: dropouts
From:       Stefan Westerfeld <stefan () space ! twc ! de>
Date:       2000-05-08 21:39:40
[Download RAW message or body]

   Hi!

On Mon, May 08, 2000 at 12:33:51PM +0200, Ken Haste Andersen wrote:
> I've recently downloaded the artsd sources and have begun playing around
> with them. It semms like a very nice framework, though the documentation
> could be a little more developed. I've begun writing a small DJ
> application using artsd. However, I have a basic problem, namely on my
> home-machine, it is not possible to stream more than one stream at a time.
> If I stream more than one stream (i.e. by artscat), mainly noise comes
> out. However, on my machine at work there are no problems.
> 
> My homemachine has a awe32 (soundblaster) soundcard, while the one at work
> has a cheap pci-soundcard. Does anybody have an idea of what is
> wrong? Could it be due to a bad awe32 sound driver?
> 
> Any suggestions would be appreciated.

First, and most important: the streams are not clipped nor scaled unless you
run artscontrol, so you either make sure that - if you have two streams -
each of the streams doesn't use more than the signal range from -0.5 to 0.5,
or you will get really strange noise effects. If you have artscontrol, you
get clipping (look at the StereoVolumeControl implementation in the source...
;), and can adjust the volume properly.

Then there are a few other things regarding real dropouts: running as realtime
process helps (start artswrapper instead of artsd and chown root artsd and
artswrapper, and make *only* artswrapper suid root). Then, make sure that
the fragment count/size settings are not too tight (see artsd -?).

Using SCSI disks instead of IDE seems to have a major impact, too.

And finally, on the side of the implementation: don't stream to the server,
but implement your app as objects which run on the server - this saves
context switching and transfer overhead, and makes the objects run with the
same priority as artsd, which could be realtime if you used artswrapper or
similar.

   Cu... Stefan
-- 
  -* Stefan Westerfeld, stefan@space.twc.de (PGP!), Hamburg/Germany
     KDE Developer, project infos at http://space.twc.de/~stefan/kde *-

[prev in list] [next in list] [prev in thread] [next in thread]