Path: utzoo!attcan!uunet!husc6!bloom-beacon!tut.cis.ohio-state.edu!mailrus!ames!eos!phil
From: phil@eos.UUCP (Phil Stone)
Newsgroups: comp.sys.amiga
Subject: Re: Sampling at 29KHz (long)
Message-ID: <765@eos.UUCP>
Date: 24 May 88 18:43:19 GMT
References: <2845@polya.STANFORD.EDU> <734@eos.UUCP> <53788@sun.uucp> <5637@cup.portal.com>
Reply-To: phil@eos.UUCP (Phil Stone)
Organization: NASA Ames Research Center, Calif.
Lines: 46

In article <5637@cup.portal.com> doug-merritt@cup.portal.com writes:

....Doug Merritt explains some interesting ways of avoiding sampling
aliasing using random fluctuations in sampling frequency....

>Now as to Phil's posting:
>
>Phil Stone then posts to critique Tom's perfectly good article,
>in particular about its length and unrealistic examples. Just for
>the record, Phil's article was almost as long as Tom's (66 vs 84 lines),
>and used even less realistic examples, because he concentrated on
>what he wanted to see added to the system, where everyone else has
>been talking mostly about what *is*. People who live in glass houses...
 
Never thought suggestions for improvement were unwelcome here, Doug.
I made an effort to point out that I regularly program and perform live
using the Amiga sound interface, and had encountered some practical
drawbacks.  Alot of the postings on this subject have been very 
educational treatises on sampling theory that seem to come from very
informed people, but none seemed to have the perspective of actually
writing software for the sound device.  I apologized to Tom via Email
(and now publicly) for flaming his well-written article, but it came
from a sense of people approaching the issue from a purely theoretical
point of view.  How many people who have said "29 KHz is not a problem"
actually write code for the sound device (never mind try to use it live!)

Your suggestions on direct (non-DMA) access of the sound device are,
once again, wonderful from a theoretical point of view, but would drain
so much CPU time as to make the Amiga difficult to use for other tasks
in a live context.  

Allow me to summarize my position:  I *love* the Amiga sound device,
and find no parallel to it in music: low-price, flexible programmability,
built-in to a superior microcomputer system with all that implies
(peripheral access, excellent software, etc).  But to say that it has
*no problems*, even if you back this up with a ream of sampling theory,
is pure defensiveism.  Maybe we can work some of these problems out before
the next generation of machines goes into production.

P.S. I promise to try to think a little more before following up in
the future.  Sorry, Tom.

			Phil Stone
phil@eos.arc.nasa.gov
phil@eos.UUCP
{ uunet, hplabs, hao, ihnp4, decwrl, allegra, tektronix } ames!eos!phil