52 lines
1.3 KiB
Racket
52 lines
1.3 KiB
Racket
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#lang racket
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;; status - working as of 20220820
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(require rsc3)
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;; shepard tones (alberto de campo)
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(define iota
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(lambda (n l j)
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(if (= n 0)
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null
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(cons l (iota (- n 1) (+ l j) j)))))
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(define indxs
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(lambda (n l r)
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(iota n l (/ (- r l) n))))
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(define hanning-window
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(lambda (n)
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(let* ((lp (* pi -0.5))
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(rp (+ lp (* 2 pi)))
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(hf (lambda (i) (+ (* (sin i) 0.5) 0.5))))
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(map hf (indxs n lp rp)))))
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(define square (lambda (x) (* x x)))
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(define amp-table (map square (hanning-window 1024)))
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(define amp-f (lambda (i) (* (expt 0.5 i) 20000)))
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(define freq-table (map amp-f (indxs 1024 0 10)))
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(define shepard-tones
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(let* ((rate-scale (/ (/ 1024 44100) 10))
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(rate 0.1)
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(ph (phasor ar 0 (* rate rate-scale) 0 1024 0))
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(phases (make-mce
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(map
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(lambda (n) (add (mul3 n 0.1 1024) ph))
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(enum-from-to 0 9))))
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(freqs (buf-rd-c 1 ar 1 phases 1))
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(amps (buf-rd-c 1 ar 2 phases 1)))
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(mul (mix (mul (sin-osc ar freqs 0) amps)) 0.1)))
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(with-sc3
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(lambda (fd)
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(async fd (b-alloc 1 1024 1))
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(async fd (b-alloc 2 1024 1))
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(send fd (b-setn1 1 0 freq-table))
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(send fd (b-setn1 2 0 amp-table))
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(audition (out 0 shepard-tones))))
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