From owner-freebsd-multimedia  Tue Aug 26 14:00:17 1997
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To: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
cc: tinguely@plains.NoDak.edu, freebsd-multimedia@FreeBSD.ORG, sales@omt.com
Subject: Re: Regard to phone call about FreeBSD drivers 
In-reply-to: Your message of "Tue, 26 Aug 1997 21:37:55 +0200."
             <199708261937.VAA00302@labinfo.iet.unipi.it> 
Date: Tue, 26 Aug 1997 13:58:52 -0700
From: Amancio Hasty <hasty@rah.star-gate.com>
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If the opti931 based soundcards derive their clock timing info then
you have a bigger problem because typically the isa timing info
is not very accurate.

Don't worry about your english . My english is far worse than yours 8)

I am Puerto Rican

	Cheers,
	Amancio
>From The Desk Of Luigi Rizzo :
> > >From The Desk Of Luigi Rizzo :
> > > make it $20-$40 for a soundcard. The OPTI931 has a street price of $20
> > > here in italy, and CS4236 (assuming you can find them) are little more
> > > expensive. For conferencing purposes they are both more than ok
> > > (Crystal much better since it is better documented and less buggy...)
> > 
> > Well, it depends the clock they use and the quality of the analog
> > parts. Conferencing is one thing however I think that you may 
> > want to use the soundcard for other things like playing back
> > audio mpeg files. By far most PC soundcards fall short on 
> > the clock part . Interestingly, the old sparcs used to have a
> > a cs4231 and the accuracy of their dsp subsystem has always
> > been better than your typical PC soundcard -- the primary difference
> > from an accuracy stand point of view is just the clock part.
> 
> the opti931 boards I have take the clock from the 14.3xxx clock on the
> ISA bus, but the internal division do not yeield the exact frequencies
> (44.1KHz, 8KHz, etc.) one would want, there is some 0.15% or so of
> difference. I doubt one would notice this (well unless it uses several
> machines  with different clocks at the same time to simulate an
> orchestra, each machine playing a different set of instruments...).
> 
> Also, if there are no short term drifts I believe the
> differences can be compensated (e.g. in software by adding/dropping
> samples every now and then).
> 
> Apart from clock stability, I suppose that dma overruns/underruns might
> also make the clock appear to have a different frequency (sorry for the
> convoluted sentence, I am italian...).
> 
> 	Cheers
> 	Luigi