;; sndfile

(define au-magic #x2e736e64)

(define au-unspecified 0)
(define au-mulaw8 1)
(define au-linear8 2)
(define au-linear16 3)
(define au-linear24 4)
(define au-linear32 5)
(define au-float 6)
(define au-double 7)

(define au-size-of
  (lambda (e)
    (cond ((= e au-unspecified) (error 'au-size-of "unspecified encoding"))
          ((= e au-mulaw8) 1)
          ((= e au-linear8) 1)
          ((= e au-linear16) 2)
          ((= e au-linear24) 3)
          ((= e au-linear32) 4)
          ((= e au-float) 4)
          ((= e au-double) 8)
          (else (error "au-size-of: illegal encoding")))))

(define au-mk-hdr
  (lambda (nf enc sr nc)
    (let ((nb (* nf nc (au-size-of enc))))
      (concat-map encode-i32 (list au-magic 28 nb enc sr nc 0)))))

(define au-f32 (list au-float encode-f32))
(define au-f64 (list au-double encode-f64))

(define write-snd-file
  (lambda (e sr nc fn d)
    (let ((enc (car e))
          (encdr (cadr e))
          (nf (/ (length d) nc)))
      (with-output-to-file fn
        (lambda ()
          (for-each write (au-mk-hdr nf enc sr nc))
          (for-each write (concat-map encdr d)))))))