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Mon Jun 8 20:37:35 CEST 2009

Busy-Beaver sound

Something like[1] but instead of a maximal run length, a maximal
"meaningful" run length with sound output.  Maybe this doesn't make
much sense for a finite machine though..

However, this is related to the idea of "maximum spaghetti code".
Code which is written in non-modular form to maximize utility towards
a particular goal, achieving maximum "amplification of behaviour" by
giving up locality, a key element of modular design.  This idea comes
from I think a Vernor Vinge novel.  It's also related to the
self-modifying noise machine ap0202[2].  The original thought inspired
by this program[3] to encode PCM for playback on an MSX using the 3
PSG channels and an optimal driving strategy, however that is not
autonomous.

Meaningful sound could be short static grains of simple modulations.
Maybe a genetic algorithm on top of sheepsint is more interesting,
like Dave's Fastbreeder[4].

My hunch is that, since the synth itself is quite simple, the
interesting sounds are going to be configurations changes over time on
top of that.  The deal is to find a machine encoding that has maximum
interestingness for a minimum number of bits.  Some elements that
work:

 - logarithmic frequency scales
 - counters
 - FSR sequences
 - stacks (push sound, change, pop sound)
 - bias towards low frequencies (drone)
 - repetitive drum patterns


Instead of looking at state machines that output all-audible sound, it
might be more interesting to look at the lower part of the spectrum
only, which consists of the average behaviour of the "fast bits" of a
binary modulated signal.  More precisely, when the "sound state" of a
machine is an 8-bit value, the audio output could be the carry flag of
an 8-bit accumulation.  This is the simplest sigma-delta modulator,
and works well for a PIC chip.  In fact, this might be used as an
"external synth".  Configuring one of the simplest PICs that have an
internal OSC to work as a (serially controlled) sound generator.



[1] http://en.wikipedia.org/wiki/Busy_beaver
[2] http://1010.co.uk/ap0202.html
[3] http://www.msx.org/PCM-Encoder-0.01.newspost3520.html
[4] http://www.pawfal.org/Software/fastbreeder/

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