Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!samsung!spool.mu.edu!news.cs.indiana.edu!bsu-cs!bsu-ucs!00csgunn
From: 00csgunn@bsu-ucs.uucp (II INFINATUM)
Newsgroups: comp.lang.pascal
Subject: Re: Sound compression
Message-ID: <60045@bsu-ucs.uucp>
Date: 13 Feb 91 07:42:51 GMT
References: <25947@adm.brl.mil>
Organization: Ball State University, Muncie, In - Univ. Computing Svc's
Lines: 25

In article <25947@adm.brl.mil>, sbarnhar%MAILBOX.MAIL.UMN.EDU@uga.cc.uga.edu
 (Shawn Barnhart) writes: 

> There are (supposedly) "advanced" compression utilities for the Mac that can
> obtain 20-30% compression of digitized sound (as opposed to resampling).
> I don't know what algorithms they may use, though. I imagine they are
> proprietary versions of some of the more standard algorithms.
> -Shawn

The routines used to compress digitized sound flies on the Mac, and the Apple
IIgs for that matter, use a rather weird compression algorythm. They look
at the sound as that... Sound. And predict what the next few bytes of the
waveform will look like. If the prediction is right, then the data can 
be compressed. Im know this is rather vague, but this is how it was
described to me. There is also another compression on the IIgs that gives
either 3:8 or 4:8 compression. Im not really sure how that works either.

Hope this helps.

-- 
--------------------------------------------------------------------------------
Steve Gunn                 Internet --> hangtime@bsu-cs.bsu.edu
The Indiana Academy                     00csgunn@bsu-ucs.bsu.edu
Ball State University      UUCP --> {BackBones}!iuvax!bsu-cs!hangtime
Muncie, IN  47306-0655              {BackBones}!iuvax!bsu-cs!bsu-ucs!00csgunn