Re: Kernel OSS vs ALSA
Martin Dalecki (dalecki@cs.net.pl)
Thu, 14 Oct 1999 22:23:21 +0200
Thomas Sailer wrote:
>
> Michael Poole wrote:
> >
> > Thomas Sailer <sailer@ife.ee.ethz.ch> writes:
> >
> > > > * simultaneous multiple streams, with mixing as needed
> > >
> > > User space IMO
> >
> > Bad idea IMO. For highly interactive applications (eg games, but also more
> > serious applications of VR) you don't want to take (a minimum of) a full
> > context switch before the sound card even has a prayer of seeing a new
> > audio sample. It's just not reasonable to restrict access to the audio hw
>
> Having format converters and sample rate converters in the kernel is
> scary.
> Straight mixing is doable, but that means that every app accessing sound
> has to be using the same format, likely the best the sound hardware can
> support,
> i.e. 48kHz 16bit 2channels for most current hardware. While this
> may not necessarily break the OSS API, it will break many current
> OSS apps. And yes, no mmap
I can just *emphasize* on this aspect of the whole:
Doing sample rate conversion is an NOT AT ALL trivial task!
Any trivial interpolation will have at best laughable results.
There where times I where coding signal processing stuff, and writing
proper adaptive filters itsn't something that should be
done inside the kernel and it can be done (almost) poperly in a generic
way.
Or is there somebody out there who would wish to have the whole LINPACK
inside of the kernel????!!!!
Just have a look at the posix RT calls and thing which use could be made
of the for a user land daemon. If the context switch latency is a
concern
in some gaming, then, well really better tell the user to get a bigger
processor.
--Marcin
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