Subsequence¶
A generative MIDI sequencer for Python — your composition, expanded by algorithms you direct, playing your synths, drum machines and DAW.
You bring the ideas; Subsequence gives you the tools to shape them. Place notes by hand, or hand parts to generators you steer — Euclidean rhythms, evolving harmony, motifs and form — deciding how far each takes your music and tuning exactly how it behaves. Reach for them where you want movement, and keep a tight hand everywhere else. It makes no sound of its own: it speaks pure MIDI, so your own instruments give it voice.
Where to start¶
New here? Start with this. A gentle, step-by-step guide from your first drum loop to live generative performance.
Already building? Look up any class, method or function — pinned to the same version as the cookbook.
Want the code? The full source, examples and issue tracker.
What’s inside¶
Every part stays aware of its surroundings — the current chord, the section, the other parts — and keeps developing as the piece plays, so your music grows rather than repeats.
Euclidean rhythms from geometry, cellular automata and L-systems from nature, Perlin noise from animation, Markov chains and chaotic maps from probability — combine and layer them freely.
Chord progressions, weighted chord graphs, and voice-leading that models how listeners expect music to move.
Motifs, phrases, sections and form — shape a whole piece at the macro level, not just one bar at a time.
Place every note by hand, hand the whole thing to the algorithms, or blend the two and dial it to taste.
Live coding, deterministic seeds, Ableton Link, OSC, MIDI in/out and external clock, a web dashboard (beta), and MIDI recording.
A taste¶
A whole evolving groove in a handful of lines — drums and a bassline that keep shifting as they play:
import subsequence
import subsequence.constants.instruments.gm_drums as gm_drums
comp = subsequence.Composition(bpm=120, key="A", scale="minor", seed=1)
@comp.pattern(channel=10, beats=4, drum_note_map=gm_drums.GM_DRUM_MAP)
def drums(p):
p.euclidean("kick_1", pulses=4) # four on the floor
p.euclidean("hi_hat_closed", pulses=11, velocity=(60, 90)) # 11 hits over 16 steps — a rolling groove
p.euclidean("snare_1", pulses=16, probability=0.15) # sparse, ever-shifting ghost snares
@comp.pattern(channel=1, beats=4)
def bass(p):
p.euclidean(45, pulses=5, duration=0.4) # a five-pulse bassline, in key
comp.render(bars=8, filename="demo.mid") # writes a MIDI file — or call comp.play() to drive your gear live
Every bar is rebuilt from scratch with the current musical context, so those parts keep drifting and developing as the piece runs — and because it’s seeded, the same performance plays back perfectly every time.
Runs on what you’ve already got¶
Subsequence is free and open-source under AGPL-3.0. With no audio engine to power, it’s light to run — an old laptop or a Raspberry Pi is plenty — so you don’t need expensive hardware to make serious generative music. Composition, after all, is about ideas — rhythm, harmony and shape — more than equipment.