music-utilities.lisp

   1
   2 (in-package :mumble)
   3
   4 (defconstant +seconds-per-minute+ 60)
   5
   6 (defun duration-to-frames (duration tempo &optional (frequency 50))
   7   "Returns a /fractional/ duration -- the conversion routine is
   8 responsible for dealing with these fractions as it sees fit."
   9   (let ((count (/ (/ frequency (/ tempo +seconds-per-minute+))
  10                   (duration-denominator duration))))
  11     ;; dots
  12     (do ((dots (duration-dots duration) (1- dots))
  13          (extra (/ count 2) (/ extra 2)))
  14         ((not (plusp dots)))
  15       (incf count extra))
  16     ;; XXX staccato, ties
  17     count))