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mods to sndfile.rkt

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This commit is contained in:
John Clements 2010-09-08 16:55:18 -07:00
parent 41e4470f23
commit 93ee20e290
1 changed files with 16 additions and 21 deletions
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37
collects/ffi/examples/sndfile.rkt
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@ -460,32 +460,27 @@
(define (write-sound* file data meta)
(write-sound-internal/lists file data meta))
;; an rsound (racket sound) provides a representation for sounds
;; that leaves them packed as C data. For the moment, it's
;; 2-channel float only. Also, it discards all meta-information
;; except length and sample-rate.
;; a rsound is (rsound _cpointer nat nat)
(provide (struct-out rsound))
(struct rsound (data frames sample-rate))
;; here's a simplified interface that leaves sounds packed as
;; C data. It's 2-channel 32-bit float only. Also, it discards
;; all meta-information except length and sample-rate.
;; these readers and writers short-cut the translation to/from lists.
;; read-rsound : path-string -> rsound
;; read the file into a rsound
(provide read-rsound)
(define (read-rsound file)
;; read-sound/floatblock : path-string -> (list/c _pointer nat nat)
;; read the file into a buffer, return the data, the number of frames,
;; and the sample rate.
(provide read-sound/floatblock)
(define (read-sound/floatblock file)
(parameterize ([sample-type 'float])
(let*-values ([(cblock meta) (read-sound-internal file #:split #f)])
(rsound cblock (cadr (assq 'frames meta)) (cadr (assq 'samplerate meta))))))
(list cblock (cadr (assq 'frames meta)) (cadr (assq 'samplerate meta))))))
;; write-rsound : rsound path-string -> (void)
;; write the rsound to the given file as a wav.
(provide write-rsound)
(define (write-rsound sound file)
(write-sound-internal/cblock file (rsound-data sound) '(wav float file)
(rsound-sample-rate sound)
(rsound-frames sound)
;; write-sound/floatblock : _pointer nat nat path-string -> (void)
;; write the floatblock sound to the given file as a wav.
(provide write-sound/floatblock)
(define (write-sound/floatblock data frames sample-rate file)
(write-sound-internal/cblock file data '(wav float file)
sample-rate
frames
2
'float
;; for now, no meta-data possible.