Autcsrgv.142
net.music
utcsrgv!chris
Mon Mar 1 15:51:37 1982
Subject: Reply to queries from watmath!jcwinterton
The gentleman from UofT was Bill Buxton, using the SSSP
(Structured Sound Synthesis Project) real-time digital synthesizer.
I worked for the SSSP for 8 monthes in 1981, and am still working parttime
with the group. All the hardware was made by this group, which worked
under the CSRG (Computer Systems Research Group) at UofT.
The touch tablet you described was thrown together rather quickly
as a prototype. A new tablet is now being worked on that will be simpler
and cheaper. Pressure was not actually used to obtain z axis values;
instead, capacitance on the tablet was measured. Human fingers flex when
pushed against something solid, so finger pressure roughly translates into
a greater capacitance effect, which means a higher Z value.
Some other things that were put together are
(1) a sound localization system, that tracks up to 4 distinct sounds
around a room using up to 16 daisychained speakers with special mixers,
audio amplifiers + logic attached to each speaker cabinet. One coax carries
the 4 audio signals + control logic (attenuations at speaker crosspoints).
(2) the aforementioned digital synthesizer, which has 4 distict audio
output signals and 16 virtual oscillators -> so up to 16 waveforms
or 8 FM (frequency modulated) sounds, or 8 voice shaped sounds can be
heard at a time. Other techniques of sound synthesis are also available.
(3) tons and tons of graphics software to allow composers to write scores,
design instruments (objects of sound, e.g. an FM sound with explicitly
drawn sound waves or volume envelopes), design waveforms, etc. Most of the
graphics uses a Graphics Wonder driven by a C library of routines called
GPAC, developed here by Bill Reeves. This all runs on a PDP 11/45.
(4) conducting tools (which Bill Buxton demonstrated to you) that allow
scores to be played while dynamically changing playing characteristics such
as note articulations, score tempos, score octave, volume, richness of sound,
score cycling (repeated playing), and score triggering (having a score or
an event trigger another score).
(5) an 88 key keyboard that has a 6800 inside that determines key push,
key release, and speed of key pushing/releasing, and time since a key
was last released, and time since key was pushed (when released).
All of this information is sent as ascii characters down an asynch line.
(6) slider boxes, that represent infinite potentionmeters.
and so on....
Currently, work is proceeding to develop CAI programs with
the Faculty of Education, so that kids can learn musical notations
and games with the system; CAI programs to help provide aural training
to musicians, and the continual use of the system by members of the
Faculty of Music and members of the Canadian Electronic Ensemble to
write scores.
The synthesizer is controlled by an LSI 11, which can be
taken to concerts, et cetera, once music has been composed and stored
on floppy disks. When used to develop scores, the LSI is connected to
the PDP 11 by a parallel port.
An FM radio is inside the synthesizer, and can be tuned by
software. Therefore, in Toronto, we sit in our lab and type
$ radio cbc 64
to get the CBC (at a volume of 64 -> volumes from 0 (off) to 64 are allowed).
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Bruce Jones, Henry Spencer, David Wiseman.
