Thoughts on Parallel Computing for Music
Miller Puckette Department of Music
University of California San Diego [email protected]
The recent history of multiprocessing in computer music has
presented us with a interesting reversal. In the early 1980s,
crunching audio samples seemed a much more computationally
intensive task than musical decision making, and research at MIT,
Stanford, and IRCAM focused on figuring how to get a few hundred
MIPS out of a machine for doing audio synthesis and processing. The
only possible way forward was multiprocessing, and the Samson box,
the 4X and the ISPW were responses to that. The ISPW, which came
fully on line in about 1991, had up to six processors. Carefully
optimized applications could attain some 300 MIPS of
throughput.
Since that time, the processors themselves have radically sped
up, to the point that only a very small number of computer
musicians complain that they can't now realize their synthesis and
processing aims with a uniprocessor. On the other hand, musical
decision making, which frequently makes heavy use of learning
algorithms, combinatorial optimization, and/or data-intensive
searching, emerges as a bottomless pit of demand for more MIPS,
storage, and communications capacity.
It turns out that audio crunching isn't too hard to parallelize
out to small numbers of processors (fewer than 10, say). The same
techniques we used in the 80s and early 90s remain valid today.
Audio "signals" and "control messages" (the dominant abstractions
of the moment for describing audio computation) can simply be
packaged and routed among processors for computation via a static
network of unit generators each assignable (either manually or
automatically) to an available processor. For example, the modern
DAW station does this, in that plug-ins seem to be where the MIPS
are truly needed; and because of the way the plug-in paradigm is
designed, individual instances are easy to farm out to available
processors.
My own project of the last ten years, Pd, is an explicit
acknowledgement that we no longer truly need multiprocessors to do
computer music; my own belief is that the important thing now is to
lower the cost of entry, and low-cost computers are still mostly
uniprocessors. (Nonetheless, because of a musical project I'm now
working on, I just recently ended up having to re-implement the old
ISPW multiprocessing approach, which is now done in an object I
call "pd~". This sprouts a pd sub-process -- from within Pd or Max,
take your pick connected by audio and control message pathways to
the calling program. I anticipate that it will be most useful for
solving interoperability problems between Max and Pd, although in
principle one could use it to load a modern several-processor
machine efficiently.)
But the real promise of highly parallelized computation (that
is, computation requiring more than two to four processors) is
probably in the decision-making tasks that are used in
computer-aided composition and improvisation - that is, the
learning, optimization, and search problems. I don't know how to do
it, but I think it would be interesting to try to make
multiprocessing implementations of engines for solving these
classes of problems.
I don't think that the way we program computers today will ever
change. The bulk of applications to which we now turn uniprocessing
machines (or dual processors with one processor idling, as seems to
be the norm today) will stay useful, and nobody will figure out how
to parallelize them. Instead of attempting that, we should look for
new styles of computing, more adaptable to multiprocessors that
could complement or augment what we do today.
Computer music seems to be an excellent source of interesting
computing problems, and we should always remind our friends in
computer science departments and in industry of this. In the same
way that real-time techniques were invented and exercised by
computer music researchers in the 1980s, today we can offer problem
spaces and innovative approaches to problems outside the reach of
conventional computers. Highly parallelizable algorithms seem
likely to be one such problem area, rich in challenges and in
promise.
IndexICMC 2008 HomeConference InfoWelcome from the ICMA
PresidentICMA OfficersWelcome from the ICMC 2008 Organising
CommitteeICMC 2008Previous ICMCsICMC 2008 Paper Panel & Music
CuratorsICMC 2008 ReviewersICMC 2008 Best Paper Award
SessionsMonday, 25 August 2008Languages and Environments
1Interaction and Improvisation 1Sound SynthesisComputational
Modeling of MusicDemos 1Posters 1Interaction and Improvisation
2Aesthetics, History, and Philosophy 1
Tuesday, 26 August 2008MiscellaneousAlgorithmic Composition
Tools 1Network PerformanceComputational Music Analysis 1Panel 1:
Reinventing Audio and Music Computation fo ...Panel 2: Towards an
Interchange Format for Spatial ...
Wednesday, 27 August 2008Studio Reports 1Mobile Computer
Ensemble PlayDemos 2Posters 2Algorithmic Composition Tools
2Interface, Gesture, and Control 1
Thursday, 28 August 2008Interface, Gesture, and Control
2Languages and Environments 2Spatialization 1Computational Music
Analysis 2Panel 3: Network PerformanceDemos 3Posters 3
Friday, 29 August 2008Sound ProcessingAesthetics, History, and
Philosophy 2Interface, Gesture, and Control 3Spatialization
2Algorithmic Composition Tools 3Studio Reports 2
AuthorsAll authorsABCDEFGHIJKLMNOPQRSTUVWYZ
PapersAll papersPapers by Sessions
Topicscritical theory/philosophy of technology, postmodern cy
...sociology/anthropology of everyday sounds, situated per
...history of computer music, women and gender studies, ed
...philosophy/culture/psychology, music information retrie
...electroacoustic music composition, aesthetics of music,
...singing analysis/synthesis, music analysis/synthesis, v
...interactive and real-time systems and languages, music
...human-computer interaction, sound synthesis/analysis, i
...interaction design, computer music, performance art, el
...physical interface design, performance systems, gesture
...language/education/history/sociology of computer music,
...composition systems and techniques, languages for compu
...programming languages/systems, audio synthesis/analysis
...composition, music cognition, music informatics, human- ...music
information retrieval, audio signal processing, p ...computational
musicology, music cognition, music and AI ...music cognition,
rhythm/meter/timing/tempo, computation ...music information
retrieval, audio content analysis, to ...spatial audio, audio
signal processing, auditory percep ...physical modelling, spatial
audio, room acoustics, aura ...sonic interaction design,
physics-based sound synthesis ...audio signal processing, sound
synthesis, acoustics of ...audio signal processing, acoustics,
software systemsphysics-based sound synthesis, virtual room
acousticscomposition, music analysis, software for pedagogyPANEL:
Towards an Interchange Format for Spatial audio ...PANEL: Network
PerformancePANEL: Reinventing Audio and Music Computation for Many
...
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