Vector to Pitch

[opmo]

An example of algorithmic composition in a few simple steps.

Initialise random seed to all functions which may use random seed.

(init-seed 8975)

 

Six lists (bars) of note-length values.

(setf len '((s s q s) (s q -s s) (s s s s) (s s -s s) (s e s) (s -s e)))

 

The GEN-SINE function generates a sequence of vectors that describe and simulate the characteristics of a sine wave.

(setf sine1 (gen-sine 12 2 0.3))
(setf sine2 (gen-sine 24 3 0.4))
(setf sine3 (gen-sine 30 4 0.5))
(setf sine4 (gen-sine 36 5 0.6))

 

Generate a graph from the data provided in these four sine sequences.

(list-plot (list sine1 sine2 sine3 sine4)
 :zero-based t :point-radius 2 :join-points t)

 

Conversion process from vector to pitch in a given ambitus.

(setf pitch1 (vector-to-pitch '(g3 g6)  sine1))
(setf pitch2 (vector-to-pitch '(gs3 g6) sine2))
(setf pitch3 (vector-to-pitch '(a3 g6)  sine3))
(setf pitch4 (vector-to-pitch '(as3 g6) sine4))

 

Combining pitches to chords. 

(setf chords2 (chordize-list (gen-combine pitch1 pitch2)))
(setf chords3 (chordize-list (gen-combine pitch1 pitch2 pitch3)))
(setf chords4 (chordize-list (gen-combine pitch1 pitch2 pitch3 pitch4)))
(setf chords  (chord-pitch-unique (flatten (list chords2 chords3 chords4))))

 

Generating length lists with the help of RND-SAMPLE and RND-ORDER functions.

(setf dur1 (rnd-order (rnd-sample 6 (rnd-sample 4 len))))
(setf dur2 (rnd-order (rnd-sample 4 (rnd-sample 4 len))))
(setf dur3 (rnd-order (rnd-sample 2 (rnd-sample 4 len))))
(setf dur4 (rnd-order (rnd-sample 4 (rnd-sample 4 len))))
(setf dur5 (rnd-order (rnd-sample 10 (rnd-sample 4 len))))

 

Generating velocity lists with the help of RND-SAMPLE function.

(setf dyn1 '(p mp mf f ff))
(setf dyn2 (rnd-sample 6 dyn1))
(setf dyn3 (rnd-sample 12 dyn1))
(setf dyn4 (rnd-sample 24 dyn1))
(setf dyn5 (rnd-sample 36 dyn1))

 

Making OMN lists.

(setf m1 (make-omn :length dur1 :pitch pitch1 :velocity dyn1))
(setf m2 (make-omn :length dur2 :pitch pitch2 :velocity dyn2))
(setf m3 (make-omn :length dur3 :pitch pitch3 :velocity dyn3))
(setf m4 (make-omn :length dur4 :pitch pitch4 :velocity dyn4))
(setf m5 (make-omn :length dur5 :pitch chords :velocity dyn5))

 

Random selection of variants.

(setf part1 (pitch-variant m1 :variant '?))
(setf part2 (pitch-variant m2 :variant '?))
(setf part3 (pitch-variant m3 :variant '?))
(setf part4 (pitch-variant m4 :variant '?))
(setf part5 (pitch-variant m5 :variant '?))

 

A pause of 1 quarter.

(setf pause '(-1/4))

 

Assembling a sequence.

(setf result (assemble-seq part1 pause
                           part2 pause
                           part3 pause
                           part4 pause
                           part3 pause
                           part2 part1
                           part5))

 

Finally, defining a score with GRAND-LAYOUT instrument - direct conversion to standard notation.

(def-score wave-to-pitch
           (:composer "OPMO"
            :copyright "Opusmodus"
            :key-signature 'atonal
            :time-signature (get-time-signature result)
            :tempo 108
            :layout (grand-layout 'piano))
  (piano :omn result :sound 'gm :channel 1 :program 0))

 

[tonality systems]

A most effective short piano piece and a good example of coding. I hope it won't be too long before a composer can add cautionary accidentals to such a score, particularly the natural sign. 

[opmo]

The cautionary accidentals  (composer intent) coming soon.

Edited July 25, 2015 by opmo