[chuck-users] random seed

Kassen signal.automatique at gmail.com
Sat Sep 11 12:55:01 EDT 2010


2010/9/11 Stefan Blixt <stefan.blixt at gmail.com>

> Gotcha! Or at least, I can see a flaw here in ChucK's randomizers: there is
> only one of them!


That's not really a flaw; everything random, including the Std.rand*
functions, all UGen noise sources and all noisy components of STK
instruments depend on the same PRNG. I looked at the source back when I was
obsessed with audio-rate resetting of the seed. This means that pieces with
a set seed will be perfectly and sample-accurately be reproducible. CSound
has always taken that into account, as well as backwards compatibility,
which means that we can now listen to CSound pieces composed decades ago
using modern converters for exact accuracy.

This is a non-trivial feature from a "serious computer music" point of
view.

What we can do is implement our own PRNG in ChucK. Random number generators
have been under a LOT of analysis as cryptographic security and thus banking
and government secrets depend on them. To facilitate this PRNG of a strength
way beyond our needs are open and free.

For a more music-based look at it all I can't recommend "A Look at random
Numbers, Noise and Chaos with Csound" by John Ffitch in the CSound handbook
highly enough. Sadly I can't quickly find a online version; you may be more
lucky or a local library might (should!) have the book.

Yours,
Kas.
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