Blogs | Michele Pasin

Apr 2021

#algorithmiccomposition
#extempore

Composition: 'Rhythmic Cycles' with Extempore

A new livecoding composition using Extempore and Ableton Live: 'Rhythmic Cycles'.

Using 'map' to trigger repeated notes

The gist of this experiment rotates around the map function.

A seed list of notes, and one of offsets , is used to generate musical play sequences:

(map (lambda (x y z)
      (onbeat x 0 (play y z (* dur .9) 1))
        )
    times
    notes
    volumes
    )

This technique generates a texture of sounds with a touch of randomness.

If the pattern above gets repeated, changing the input parameters periodically leads to the generation of very interesting musical patterns.

For example:

times can be shifted up or down by 1/4 beat or so
notes can be transposed using different chord structures
volumes can use cyclical variations eg a cosine function

The end result reminds me of a hypnotical tune that keeps repeating but it's never exactly the same. Similar to 8-bit video game music patterns, but obviously when using more interesting sounds/instruments to begin with, the end result is more engaging too.

Source code

The full source code can be found on Github.

(define notes (list c3 g3 bb3))

(define times (:mklist 8 (oneof 1/2 1/4)))

(define inc
    (lambda (alist)
        (map (lambda (x)
                (if (< x 1) 
                    (ifr .7 (add 1/4 x) x) 0)
                )
            alist)
    ))


(define lp1
    (lambda (beat)
        (let ((dur 1/16)
              (v1 (cosr (cosr 50 18 1/64) 30 1/64))
              (v2 (cosr (cosr 50 18 1/150) 30 1/40))
              (fc 8))

            (println v1 v2)

            (onbeat 4 0 
                (set! times (inc times)))

            (onbeat 32 0
                (if (< v1 40)  
                    (set! notes (rotate notes -1))))

            (map (lambda (x y z)
                  (onbeat x 0 (play y z (* dur .9) 1))
                  (onbeat x 0 (play y z (* dur .9) 3))
                    )
                (slice fc times)
                (slice fc  (:mkchord (car notes) '-6 8))
                (slice fc  (list v1 v2 v1 v2 v1 v2 v1 v2))
                )

            (callback (*metro* (+ beat (* 1/2 dur))) 
                'lp1 (+ beat dur)))))

(lp1 (*metro* 'get-beat 1))

Cite this blog post:

Michele Pasin. Composition: 'Rhythmic Cycles' with Extempore. Blog post on www.michelepasin.org. Published on April 10, 2021.

Composition: 'Rhythmic Cycles' with Extempore

Using 'map' to trigger repeated notes

Source code

See also: