71 lines
1.4 KiB
Racket
71 lines
1.4 KiB
Racket
#lang scribble/manual
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@(require (for-label racket))
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@title{(fb-sine-c rate freq im fb a c xi yi)}
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Feedback sine with chaotic phase indexing.
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freq - iteration frequency in Hz - 22050
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im - index multiplier amount - 1
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fb - feedback amount - 0.1
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a - phase multiplier amount - 1.1
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c - phase increment amount - 0.5
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xi - initial value of x - 0.1
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yi - initial value of y - 0.1
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A cubic-interpolating sound generator based on the difference
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equations:
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xn+1 = sin(im*yn + fb*xn)
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yn+1 = (ayn + c) % 2pi
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This uses a linear congruential function to drive the phase
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indexing of a sine wave. For im = 1, fb = 0, and a = 1 a normal
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sinewave results.
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sclang default values
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@racketblock[
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(audition
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(out 0 (mul (fb-sine-c ar (fdiv sample-rate 4) 1 0.1 1.1 0.5 0.1 0.1)
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0.2)))
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]
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increase feedback
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@racketblock[
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(let ((fb (line kr 0.01 4 10 do-nothing)))
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(audition
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(out 0 (mul (fb-sine-c ar sample-rate 1 fb 1.1 0.5 0.1 0.1) 0.2))))
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]
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increase phase multiplier
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@racketblock[
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(let ((a (line kr 1 2 10 do-nothing)))
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(audition
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(out 0 (mul (fb-sine-c ar sample-rate 1 0 a 0.5 0.1 0.1) 0.2))))
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]
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randomly modulate parameters
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@racketblock[
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(let* ((x (mouse-x kr 1 12 0 0.1))
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(f (lambda (m a) (mul-add (lf-noise2 kr x) m a))))
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(audition
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(out 0 (mul (fb-sine-c ar
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(f 1e4 1e4)
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(f 32 33)
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(f 0.5 0)
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(f 0.05 1.05)
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(f 0.3 0.3)
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0.1
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0.1)
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0.2))))
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]
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