Path: utzoo!utgpu!news-server.csri.toronto.edu!qucdn!leek
Organization: Queen's University at Kingston
Date: Monday, 25 Mar 1991 21:21:15 EST
From: <LEEK@QUCDN.QueensU.CA>
Message-ID: <91084.212115LEEK@QUCDN.QueensU.CA>
Newsgroups: comp.compression
Subject: Re: Compressing SOUND files (8 bit amplitudes)
References:  <394@uqcspe.cs.uq.oz.au>

I am not into this area, but I came across a little bit of material on the
subject...  If you don't mind the lost of sound quality, then there is a
technique call "Fibonacci Delta Compression" (1)

This is like the trasitional delta encoding where each value is a delta of
the previous one, but only discrete delta values are used.  Small delta
deltas are encoded precisely, and large ones are approximated.  From time
to time, some minor adjustments have to make to correct for all those
approximations.  This is more of a post processing thing unless your
hardware happens to be able to process the incoming digitizing sample
without much help from the CPU (eg. DMA)

The values he uses are: { -34,-21,-13,-8,-5,-3,-2,-1,0,1,2,3,5,8,13,21}
(Numbers that are part of Fibonacci series and hence the name) Note that the
delta value can be encoded in 4 bit with some minor distortion.

K. C. Lee
Elec. Eng. Grad. Student

Reference
1: Algorithm by Steve Hayes at Electronic Arts.  It is outlined and shown in C
code example for the decoding algorithm in "Amiga ROM Kernal Reference Manual:
EXEC" by Commodore Business, published by Addison Wesley (ISBN 0-201-11099-7) on
Appendix B-68.  This is part of the list of program example on a common file
format (sound, graphics and lots of things) developed for (but not restricted
to)  the Commodore Amiga Computer.  Most of these stuff are in public Domain.