150
D. Rocchesso: Sound Processing
graphical building
environments
rapid prototyping tools
real-time processing
audio stream
MIDI
Kyma/Capybara
ARES/MARS
Scope
Max
time
-1.0
1.0
0.0
20.0
time
0.0
4000
0.0
20.0
Figure 3: Waveshape and sonogram of a sound file that is echoed and read at
increasing speed
inputs and outputs connected by lines, thus replicating once again the old and
well known modular synthesizer interface taxonomy.
The steady increase in performance of modern computers has allowed the
interactive use of these graphical building environments, that become effectively
rapid prototyping tools. The speed of modern processors allow sophisticated sig-
nal computations at a rate faster than the sampling rate. For instance, if the
sampling rate is F
s
= 44.1kHz, it is possible that the processor is capable to pro-
duce one or more sound samples in a time quantum T = 1/F
s
= 22.6Ásec. If such
condition holds, even the languages of section B.2 can be used for real-time pro-
cessing, i.e., they can produce an audio stream directly into the analog-to-digital
converters. The user may alter this processing by control signals introduced by
external means, such as MIDI messages
11
.
Initially, many interactive graphical building packages where created to tame
the daunting task of writing specialized code for dedicated signal processing
tasks. In these packages, each object would contain some portion of DSP as-
sembly code or microcode which would be loaded on-demand in the appropriate
DSP card. With a graphical interface the user would easily construct, then,
complex DSP algorithms with detailed controls coming from different sources
(audio, MIDI, sensors, etc.). Several such applications still exist and are fairly
widely used in the live-electronics music field (just to quote a few of the latest (re-
maining) ones): the Kyma/Capybara environment written by Carla Scaletti and
Kurt Hebel
12
, the ARES/MARS environment [7, 11, 21, 6] developed by IRIS-
Bontempi, and the Scope package produced by the german firm Creamware
13
.
While these specialized packages for music composers and sound designers
are bound to disappear with the rapid and manifold power increase of general
purpose processors
14
, the concept of graphic object-oriented abstraction to eas-
ily visually construct signal processing algorithms has spur an entire new line
of software products.
The most widespread one is indeed the Max package suite conceived and
written by Miller Puckette at IRCAM. Born as a generic MIDI control logic
builder, this package has known an enormous expansion in its commercial ver-
11
MIDI (Musical Instrument Digital Interface) is a standard protocol for communication of
musical information
12
http://www.symbolicsound.com
13
http://www.creamware.de
14
This is not a personal but rather a classic darwinian consideration: the maintenance costs
of such packages added to the intrinsinc tight binding of such code with rapidly obsolescent
hardware exposes them to an inevitable extinction.
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