Path: utzoo!mnetor!uunet!husc6!mit-eddie!bbn!rochester!PT.CS.CMU.EDU!SPEECH1.CS.CMU.EDU!phd
From: phd@SPEECH1.CS.CMU.EDU (Paul Dietz)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Sound Techniques
Message-ID: <1086@PT.CS.CMU.EDU>
Date: 10 Mar 88 06:36:44 GMT
References: <2263@saturn.ucsc.edu>
Sender: netnews@PT.CS.CMU.EDU
Organization: Carnegie-Mellon University, CS/RI
Lines: 28
Keywords: Just a guess...

In article <2263@saturn.ucsc.edu> alibaba@ucscb.UCSC.EDU (Alexander M. Rosenberg) writes:
>Beyond Dark Castle does something very neat with sound. I used a public
>domain program called Sound Leech to grab the sounds out of the file
>BDC Data A. SOUN ID 94 is the music from the title page. It is at 5.5kHz.
>The problem is, it sounds very tinny and mechanical. BDC does some manipulation
>to all its sounds when it plays them.
>
>Any ideas as to what is happening?

I have a guess with almost zero justification: Different programs use different
representations of the waveform. Some use signed integers, others just
offset unsigned integers. If you played one assuming it was the other, it
would sound pretty much as you described.

The other possibility is that you're not getting a reasonable anti-aliasing
filter. Could somebody who knows the sound hardware explain how the
anti-aliasing filter is choosen for different sampling rates? (I've
been wondering if the Mac does ANY anti-aliasing at all...)

[Actually, if it doesn't, that might also explain your problem: Maybe BDC
upsamples and interpolates at say 22kHz to solve the alaising problem...]

Paul H. Dietz                                        ____          ____
Dept. of Electrical and Computer Engineering        / oo \        <_<\\\
Carnegie Mellon University                        /|  \/  |\        \\ \\
--------------------------------------------     | | (  ) | |       | ||\\
"If God had meant for penguins to fly,             -->--<--        / / |\\\  /
he would have given them wings."            _________^__^_________/ / / \\\\-