code from class, 2013-10-14

reverse-sound.rkt

(require rsound)

;; the sample rate
(define SR 44100)
;; a helper function to simplify specifying the number of seconds
(define (s seconds) (* seconds SR))

;; read in a clip of a sound
(define samp
  (rs-read/clip "/path/to/your/sound.wav" 
                (s 500) (s 502)))

;; make a pstream
(define ps (make-pstream))
;; what is the current frame of the stream?
(pstream-current-frame ps)
;; queue a sound on 'ps' for playing at the specified frame:
(define (psq snd fr)
  (pstream-queue ps snd fr))


;(psq samp 5000)
;(psq samp (+ 5000 (s 2)))

;; a sine tone function, playing at 250 Hz.
(define (tone f)
  (* 0.1 (sin (* f 250 (/ (* 2 pi) SR)))))

;; a function to play the sample backward.
(define len (rs-frames samp))
(define (backward f)
  (rs-ith/left samp (- len f 1)))

;; play the reversed sound
(play 
(signal->rsound 
 (s 2)
 (indexed-signal backward)))