>I downloaded the GUS SDK to try out the demonstration of the 3d
>technology, and (after shifting my speakers around) I got it to work.
>It's a pretty lame demo (just a blast sound -- it also seems to
>"click" -- perhaps a bad sample??), but it does show that one can get
>the 3d effect out of two speakers. It works much better with
>headphones, though.
A friend told me about this stuff a month or so ago about how somebody had
written code for getting 3d sound. Of course, I though he was full of sh&t
at first but began to think, "hell, we have two ears, why not a headphone."
Well, I did some research, alittle digging, and came across so cool stuff.
The follows numbers are not accurate, but close.
3d Sound is a capability that can be used by any stereo sound card, you do
not need four channels to accomplish it.
This is how we hear in spatial coordinates:
Image your head is the center of a spherical coordinate system.
@ is for the degrees of deviation from the center,
% is for the degrees of latitude.
d is distance.
Any sound source can be described as (@,%,d).
Figuring d is kinda rough, without experience you really can't tell if
something is 5 ft. You basically can just tell if a sound is close (loud)
or far away (quiet). Simple division of your final sound or even subtraction
of some value of you sound can simulate this.
@ is figured by the difference in time that each ear first hears the sound.
Obviously, if your right ear hears it first, it is to your right. The amount
of time determines the degree of angle. ( I don't have the simple formula
here. )
% is determined by echo and sound shadows. Your pinnia (outter ear) creates
echos of all the sounds you hear. Stuff infront of you creates a echo that
reaches your ear about the same time that the original sound does (something in
the order of microseconds). A sound generated from behind has a delay of about
300 milliseconds.
It takes a ton of processing, but all you have to do is mix a single sound: one
for the left ear and one for the right. After calculating the delays, it is
pretty straight forward stuff.
Now, if you ever get to hear this stuff, close your eyes and you will notice
that the sounds sound like they are inside your head. Curious. The reason
for this is because your head and ears create sound shadows. Sounds from the
side and behind have some frequencies shadowed out. It all depends on the
distance between YOUR ears, the SIZE of your ears, etc. This stuff is a bitch
to do, would require capacitors and iductors to create it and then you would
have to have a card specifically designed for your head.
Also, this stuff really shouldn't work with regular speakers, you need head
phones. With regular speakers, your head may decide that the echos are
actually different sound sources and you may hear multiple sources.
Hope this helps uncover some of this mystery.
Later
Cpatri@cs.tamu.edu
Kurt
-----------------------------
Date: Sat, 22 May 93 13:48 GMT
From: EXT0012@VAX2.QUEENS-BELFAST.AC.UK
Subject: GUS DRAM Expansion
Message-ID: <9305221246.AA04450@orca.es.com>
Hi all...
Harking back to the DRAM upgrade subject, I got round the problem of added expence and hassle by butchering my Trident TVGA8900 video card.
Having only got a straight VGA monitor I can't use the higher-res modes anyway, so I transplanted the top 512k of DRAM chips from the Trident to the GUS. 4NJ/4^|MAll that's needed on the Trident is moving the DIL link chip and shifting a couple of links.
It works surprisingly well - both GUSTEST and GUSDRAM are content with it, and therefore so am I!
