My Library: RSound
My name: Doug Salvati
First, I created some functions to create notes. The user specifies a note and octave to make-note and the function calculates the frequency of this note.
From here, the user can play the note using seeAndHear. This will also use the calculated frequency to visualize the note using the plot library. Here is a sample interactive session:
The function also plays the note using the play function from rsound. To do this, it first uses the create-tone utility to create an rsound object:
;; create note at 10% volume with duration of 50000
(play (make-tone (pitch n) .1 50000))
The biggest compontent is to create a song and play it. A song is simply created as a list of notes:
(define (make-song . notes) notes)
Then, a tail-recursive function is used to play the song. The function makes use of the rsound streams, traversing the list and enqueuing each to the stream:
(define (playSong s)
(define stream (make-pstream))
(define (iter s cnt)
(if (null? s)
"everything is queued up!"
(begin (pstream-queue stream (make-tone (pitch (car s)) .1 20000) cnt)
(iter (cdr s) (+ cnt 21000)))))
(iter s 0))
It increments a count with an interval slightly longer than the duration of the note so that the notes play with a small pause between each one.
The experiment.rkt file contains a sample song which plays when the program is run.