Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!motcsd!lance
From: lance@motcsd.csd.mot.com (lance.norskog)
Newsgroups: comp.compression
Subject: Re: Compression of 16-bit sound files
Message-ID: <3564@motcsd.csd.mot.com>
Date: 4 Apr 91 00:17:27 GMT
References: <rog.670690472@color>
Organization: Motorola CSD, Cupertino CA
Lines: 19

rog@speech.kth.se (Roger Lindell) writes:

>Hello,

>I would like to know if there exists any good and moderately fast compression
>programs that will compress 16-bit soundfiles by a large amount. These files
>are stored for archiving purposes and therefore I need a non lossy compression.
> ... [ standard compresses are slow and don't do very well ]

The standard naive sound compressor is just saving the deltas between samples.
You save deltas as a stream of 2-, 3-, 4-, ..., N-bit records.

What I have noticed playing around with voice files is that they have lots
of "flip" deltas with zero-crossings.  That is: "100,-101,104,-99".
It might work well to save the deltas AND note that some
deltas have zero-crossings, thus a stream like "100,+4,+6,-7,C-9" comes
out "100,104,110,103,-112".

Lance Norskog