From mailserv@gaia.ucs.orst.edu Sun Jun 26 18:54:03 1994
Precedence: Bulk
Date: Sat Jun 25 14:05:34 PDT 1994
From: gus-sdk-request@gaia.ucs.orst.edu (GUS Programmer's Server)
Reply-To: gus-sdk@gaia.ucs.orst.edu (GUS Programmer's Digest)
Subject: GUS Programmer's Digest V12 #8

GUS Programmer's Digest     Sat, 25 Jun 94 14:05 PST     Volume 12: Issue   8 

Today's Topics:
                    HOW TO USE THE 32-BIT DRIVERS
                     Signed vs. Unsigned Samples

Standard Info:
	- Meta-info about the GUS can be found at the end of the Digest.
	- Before you ask a question, please READ THE FAQ.

----------------------------------------------------------------------

Date: Sat, 25 Jun 94 14:40:06 +0300
From: tjakobs@mswe.dnet.ms.philips.nl (THEO_JAKOBS TEL.62667)
Subject: HOW TO USE THE 32-BIT DRIVERS

Hello..

I'm currently working on a new game.. And i was wondering, where can i get 
some Information on how to use the 32-Bit AIL drivers...

Andre Jakobs
  MicroBrain Technologies Inc.
     The Netherlands

------------------------------

Date: Fri, 24 Jun 1994 18:29:56 -0400
From: davidm@marcam.com (David MacMahon)
Subject: Re: Signed vs. Unsigned Samples

>Date: Thu, 23 Jun 1994 16:09:36 -0700 (PDT)
>From: David.Roberts@amd.com (Dave Roberts)
>Subject: Signed vs. Unsigned Samples
>
>I was just sitting down the other day and thinking about mixing
>samples and the GUS and ultraclicks and so forth ('cause I do that
>sort of thing sometimes).  Anyway, I came to the conclusion that
>unsigned samples are probably bad and might be a source for many of
>the GUS's ultraclicks.

Don't you know thinking is bad for you? :-)

Basically, unsigned samples are the same as signed samples plus an offset.  
Since the GF1 only plays signed samples it is impossible for unsigned 
samples to cause ultraclicks.  If you play unsigned samples on the GF1, you 
get something that sounds *alot* worse than ultraclicks.  That aside, 
properly mixed unsigned samples will not contain any more distortion than 
properly mixed signed samples.

>Phat or Dave, did you guys come to any conclusions about this when you
>were doing your research on ultraclicks and how to avoid them?  You
>gave a lot of information about GUS interpolation idiosyncracies
>causing clicks during looping but I don't remember any mention of
>clicks at the start or end.

Clicks at the beginning and/or end of a waveform occur when the beginning 
and/or end of the waveform have a non-zero value.  This non-zero value 
causes a discontinuity in the output.  This discontinuity is heard as a 
click if the volume is high enough.  Ramping the volume from zero to the 
desired level provides a fade-in effect so that the click is not heard, but 
neither are the first few samples.  Generally, the elimination of the click 
is well worth the few missing samples.

>Just me sitting here, thinking too much... :-)

Don't worry, it happens to all of us! :-)  If you want a more detailed 
explanation, let me know.  (I just figured you'd get a bunch of replies 
saying the same thing so I tried to keep this brief!)

Dave

David MacMahon
Software Engineer
davidm@marcam.com

------------------------------

End of GUS Programmer's Digest V12 #8
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