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