From mailserv@gaia.ucs.orst.edu Mon Jan  9 14:09:55 1995
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Date: Mon Jan  9 12:06:09 PST 1995
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 V16 #2

GUS Programmer's Digest     Mon, 9 Jan 95 12:06 PST      Volume 16: Issue   2 

Today's Topics:
                    GUS Programmer's Digest V16 #1
                             homebrew...
                        Loading GUS Patches..
                             the details

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: Sun, 8 Jan 1995 20:07:56 -0800 (PST)
From: Francois Dion <francois@hyperreal.com>
Subject: Re: GUS Programmer's Digest V16 #1

> From: "Steve Shepard" <sjs@time.engr.sgi.com>
> Subject: Key Mapping in .pat files
> 
>1) Is there an assumed sample rate to MIDI key mapping (e.g the wave sample
>rate maps to C4) in the .pat file format? If not, how do you map root_frequency
>to MIDI note number?

The sample rate is stored in the patch file and so when you play the root
note, the sample will be played back at that sample rate. Other notes
are calculated in relation to this with a multiplier. Either my 1st or
second tutorial included tables for this. I would think 1st... (patchkit.arj).
Should be able to find this in the SDK too, as what i did was to take the
rates from patch.exe...

> 2) What are the units for the envelope rates and how do they relate to the
> evolution of the sound?

For the units, again look at patch.exe to convert to ms. How they relate:

When you press a key, the volume ramps from 0 to a certain value, at a
certain rate. This is the attack. While holding the note the sound can
either go directly back to 0 at a certain rate (this is the release), or
before it is released it can sustain at the same volume or it can start to
decrease or a combination of both (sustain for a certain time, then decay).
Basically then you have the attack, the decay, the sustain and the release.
The third point in the enveloppe is the sustain (when sustain is on), so
you can either use another point to release to zero or one to decay and
then release or emulate reverb by dropping and then releasing from a point
with a higher amplitude. If my memory serves me well, they are not stored
in an X,Y pair but instead amplitude, rate or time, rate (quite similar to
a r, phi coordinate.

> 3) Tuning allows you to change the pitch +- 1 octave. Is the range linear with
> frequency?

It seem that this field is now obsolete. Considering that one can change
the root note, this was not really needed.

Ciao,
-- 
Francois Dion (IdMEDIA)                   [> Email: francois@hyperreal.com <]
    '                         [> C.P. 278, St-Lambert, QC, Canada, J4P 2N8 <]
        [> Raving Up North Ezine: run-request@hyperreal.com, subject: help <]

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

Date: Sun, 8 Jan 1995 19:29:13 -0800 (PST)
From: Francois Dion <francois@hyperreal.com>
Subject: homebrew...

GUSPPG6.MP2 - Audio Mpeg (layer 2) of a Gravis Ultrasound emulating
              a PPG Wave like wavetable sweep.

In this short abstract, you'll hear one note sustained, with a volume and sweep
modulation using one potentiometer connected to the game port. Another
three can be connected to the game port, which could be used to modify the
attack and maybe a sub oscillator or something lke that, both relatively
easy to do. Or 2 joysticks, one for wavetable sweep/attack and one for
vector synthesis, the four buttons for grunge/loop direction and whatever
else...

For more details, check the file gusppg.txt in this directory also
(ftp://hyperreal.com/music/machines/emulations)

Ciao,
--
Francois Dion (IdMEDIA)                   [> Email: francois@hyperreal.com <]
    '                         [> C.P. 278, St-Lambert, QC, Canada, J4P 2N8 <]
        [> Raving Up North Ezine: run-request@hyperreal.com, subject: help <]

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

Date: Sun, 8 Jan 95 23:52:13 +0200
From: tjakobs@mswe.dnet.ms.philips.nl (THEO_JAKOBS TEL.62667)
Subject: Loading GUS Patches..

Hi..

Well I've got a problem, I'm currently working on a Midi Player, But I
Don't know how to handle the GUS Patches. What I mean is, How does one
Load A GUS Patch into the GUS-Memory, And How do I play a Note.. 
I know how to play samples with the gus, So if it is just a matter of playing
a sample, then please show me how to load a .PAT file as a sample to the 
GRAVIS...

Hope to hear something soon..

Andre Jakobs
  MicroBrain Technologies Inc.
    The Netherlands

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

Date: Sun, 8 Jan 1995 19:28:48 -0800 (PST)
From: Francois Dion <francois@hyperreal.com>
Subject: the details

IT'S A BIRD, IT'S A PPG... NO, IT'S A GUS
 ----------------------------------------

Since i got a Gravis Ultrasound in 1992, my idea has been to use it as
a synth module. Now, i know that it's a wavetable synth (one couldlso
call it a sampler, but the industry has dubbed this type of architecture
as a wavetable synth) already and that is quite flexible. However, having
owned an EPS-16+ i found that the driver and hardware lacked a few
important features in term of "tweakability". One very neat feature was
the possibility to move the loop points with an lfo, for example. With
the proper sample, you could do some weird filter sweeps or radio noises.
Owning several synths with lots of knobs that you can tweak in realtime
(from the panel or from a programmer), i also wished for a driver that
could respond to controllers to modulate some parameters.

Well, as you will hear in the MP2 files, i've achieved both. Sweeps, drones,
sample and hold, distorted sounds, metallic sounds etc...

I am aware that some clicks are still present, but this is only version
0.1 alpha of the software. Abstraction made of the clicks (timing is
critical but they can all be removed), the program can recreate a lot
of PPG sounds, from drones to sweeps to bass (i emulated in a
convincing way some PPG Wave 2.2 sounds).

I've also done a program for FM emulation and another for LA emulation
both with mixed results. However i plan to combine all of these
programs together, and also to add some other things like some drum specific
modulators, programmable modulators etc.. For the PPG sounds i use 1 voice
per sound (2 with a sub oscillator), while FM can eat up to 6 voices, but
typical use will be at 2 voices. In all i am limited of course between 14
(bright) and 32 (warm) voices, but one could also use several GUS on
the same board, creating a monster synth. Oh, and vector synthesis would
require 4 voices per sounds (SY22, Wavestation etc...)

Are there people interested in working on this for fun?
Graphics will have to be designed
Interfaces tought of (sequencer?, arpegiator, sliders etc...)
Lots of programmation to be done
Manuals (to help design the interface and options) are needed for:
-Korg Wavedrum, Wavestation
-PPG Wave
-Waldorf Microwave
-Yamaha SY...
etc...
Thanks to Rob Talley for the Roland MT32 manual

So, if you are interested in doing something, drop me a line. If you had
already contacted me at my old address (dionf@ere.umontreal.ca) about
parts of this project (including the digital out), you'll have to
recontact me cause i lost a lot of email when i switched to hyperreal.

Ciao,
--
Francois Dion (IdMEDIA)                   [> Email: francois@hyperreal.com <]
    '                         [> C.P. 278, St-Lambert, QC, Canada, J4P 2N8 <]
        [> Raving Up North Ezine: run-request@hyperreal.com, subject: help <]

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

Date: Mon, 9 Jan 1995 21:09:28 +0800
From: Paul Turbett <sls@perth.DIALix.oz.au>

I was just wondering if anybody knew of a utility that would convert a Midi
file to a MOD file. I need such a utility for a game I am writing at the
moment. Thanks.

Paul Turbett
Silver Lightning Software

sls@DIALIX.oz.au

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

End of GUS Programmer's Digest V16 #2
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