evolving rhythms

Good Morning,

i am still working on continuous parameter spaces in music composition. yesterday i wrote a simple Scheme code, which calculates interpolated values between two rhythmic sets.
arguments are:
the rhythms,
the step quantity [which determines the extent of the evolution],
the step duration [that changes the actual tempo]
and the file name [since the code outputs the data by default as a midi file].


i uploaded a sound example and Scheme code, which unfolds the evolution between the rhythms shown below.






download the code via:
ritm-interp.scm

if you want to run/hack the code, install first the Grace 

http://commonmusic.sourceforge.net/

download the sound via:
ritm-interp.mp3



;;generates interpolated values between two rhythmic sets;

(define (rhythm-interp-2 ritm1 ritm2 step step-dur file) ;
  (let* ((len-ritm1 (length ritm1))
         (len-ritm2 (length ritm2))
         (short (if (< len-ritm1 len-ritm2) ritm1 ritm2))
         (long (if (< len-ritm1 len-ritm2) ritm2 ritm1))
         (new (if (< len-ritm1 len-ritm2) (make-vector len-ritm2 0) (make-vector len-ritm1 0)))
         (new-alt (if (< len-ritm1 len-ritm2) (make-vector len-ritm2 0) (make-vector len-ritm1 0)))
         (output (list)))
    (loop for i in (vector->list new)
          for i-c from 0
          for i-c2 = (rescale i-c 0 (- (length new) 1) 0 (- (length short) 1))
          do
          (vector-set! new i-c (vector-ref short (int i-c2))))
    (if (< len-ritm1 len-ritm2)
      (loop for ri from 0 to step by step-dur
            for ri-nrmlzd = (/ ri step)
            do
            (set! output
                  (append output
                          (unique (loop for alt-i in (vector->list new)
                                        for alt from 0
                                        do
                                        (vector-set! new alt (interp ri-nrmlzd `(0 ,(vector-ref new alt) 0.1 ,(vector-ref new alt) .9 ,(vector-ref ritm2 alt) 1 ,(vector-ref ritm2 alt)) 1))
                                        collect (+ ri (rescale (vector-ref new alt) 0 1 0 step-dur)))))))
      (loop for ri from 0 to step by step-dur
            for ri-nrmlzd = (/ ri step)
            do
            (set! output
                  (append output (unique (loop for alt-i in (vector->list ritm1)
                                               for alt from 0
                                               do
                                               (vector-set! new-alt alt (interp ri-nrmlzd `(0 ,(vector-ref ritm1 alt) 0.1 ,(vector-ref ritm1 alt) .9 ,(vector-ref new alt) 1 ,(vector-ref new alt)) 1))
                                               collect (+ ri (rescale (vector-ref new-alt alt) 0 1 0 step-dur))))))))
  
    (with-midi (file)
      (loop for fi in output
            do
            (send "mp:midi" :time fi :key (between 40 67) :amp 60)))
    output))



(rhythm-interp-2 #(0.0 0.0625 0.1875 0.25 0.3125 0.375 0.4375 0.5 0.5625 0.6875 0.75)
               #(0 .33 .6) 40 2 "~/ritm.mid")








ritm-interp by Aykut Caglayan is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.