Music

Theory, Algorithmic Composition, Experimentation

A collection of Perl, Python, and R scripts for generating MIDI music, exploring music theory, and experimenting with algorithmic and mathematical composition techniques.

---

Overview

This repository is a sandbox of musical experiments spanning:

• Algorithmic composition — using genetic algorithms, cellular automata, fractals, and chaos theory to generate music
• Music theory exploration — scales, modes, chord progressions, intervals, cadences, and harmonic analysis
• Rhythm generation — Euclidean rhythms, drum patterns, MIDI drum machine scripts
• Real-piece transcriptions — faithful MIDI renderings of jazz standards and classical pieces
• Mathematical sonification — mapping physics and mathematics (Lorenz attractors, Mandelbrot sets, astrophysics data) to sound
• MIDI tooling — capture, routing, real-time clock control, and device configuration
• Hardware control — scripts that clock and drive drum machines, synths and Eurorack, plus a web UI for a Volca Drum

Almost every program is a standalone, single-file script. Many have a write-up on https://ology.github.io; look for the link in the script's header comments.

---

Languages & Dependencies

Language	Share
Perl 5	~81%
Python	~19%
R	<1%

Key Perl Modules

• MIDI::Util — score setup and MIDI helpers
• MIDI::Drummer::Tiny — drum pattern generation
• MIDI::Simple — low-level MIDI score building
• MIDI::Chord::Guitar — guitar chord voicings
• Music::Duration::Partition — rhythmic motif generation
• Music::CreatingRhythms — Euclidean and other rhythm algorithms
• Music::AtonalUtil — pitch-set operations (invert, retrograde, transpose, rotate)
• Music::Chord::Note — chord-to-note mapping
• Music::Note — note name/MIDI number conversions
• AI::Genetic — genetic algorithm engine
• Music::VoiceGen — constrained, weighted melodic voices
• Music::Scales / Music::ScaleNote — scale pitches and scale-aware note movement
• Music::Cadence / Music::Chord::Namer — cadences and chord naming
• Graph::Weighted — weighted graph walks
• MIDI::RtMidi::FFI::Device / IO::Async — real-time MIDI I/O and clocking
• Game::Life — Conway's Game of Life grid
• Math::Utils — scaling utilities

Key Python Libraries

• mido / python-rtmidi — MIDI I/O and real-time clock
• music21 — music analysis and notation
• networkx, numpy, pychord, pyyaml — graphs, math, chord names, YAML
• fritter — async clock scheduling
• The author's own packages: music_voicegen, music_melodicdevice, music_bassline_generator, music_creatingrhythms, chord_progression_network, random_rhythms, music_drummer

---

Scripts by Category

Algorithmic Composition

Script	Description
ai-genetic	Uses a genetic algorithm (AI::Genetic) to evolve a pitch set scored by consonance, then optionally evolves rhythm and velocity. Applies atonal transformations (inversion, retrograde, rotation, transposition).
ai-genetic-pro	AI::Genetic::Pro version: evolves pitches whose adjacent intervals must be 2–5 half-steps, then feeds them to contrapuntal transformations.
algo-progression	Generates a whole band by genre: chord progressions (from Music::Dataset::ChordProgressions), drums, bass line, and optional arpeggios.
algo-progression-rt.pl	Real-time version of algo-progression, played on an external device.
cope	Scores chord combinations with David Cope's tension model (Music::Tension::Cope).
cope-genetic	Genetic search over chords using Cope tension, with a dissonance threshold at the tritone.
pso-cope.pl, pso-chord.pl, pso-music.pl	Particle-swarm experiments using Cope tension and a Tenney-height dissonance model (pso-chord.pl is unfinished).
bitstring-fitness	Evolves bit-string individuals (Algorithm::Evolutionary) with a musical fitness function.
evolver.pl	Breeds MIDI phrases from a "mother" and "father" using partitions and permutations.
fragments	Builds pieces from short fragments using Music::VoiceGen and partitioned durations.
micro-themed	Micro-motifs with inversion and transposition (the header warns it "produces unsavory things").
reichify	Steve Reich-style phasing built on cyclic permutations.
tape-loop	Imitates the tape-loop effect of Eno's Music for Airports.

Chaos, Fractals & Mathematics

Script	Description
lorenz-attractor.pl	Solves the Lorenz system using RK4 integration; maps x/y/z trajectory values to MIDI pitch ranges and writes quarter-note triads. Outputs a .csv of trajectory data alongside the MIDI file.
lorenz-attractor.py	Python equivalent of the above.
mandelbrot_music.py	Sonifies the Mandelbrot set — escape count drives pitch, and duration is its inverse.
barycenter, barycenter3, barycenter4	Genetic algorithms scored with Music::Interval::Barycentric chord geometry; 3 adds cadences and rhythm partitions.
hilbert-notes	Uses a Hilbert space-filling curve to traverse a note grid.
astrophysics	Space-themed piece built on Voss noise (Music::Voss).
five-parsecs, kiloparsec	Space-themed pieces: drums with fills and crashes, and Voss-noise melodies.
event-horizon, gravity-well, sidereal-time	More space-themed pieces using scale-note walking, cadences and chords.
collision	Wind-chime simulation with Collision::2D.
base-fibo2, base-primes	Fibonacci numbers and primes rewritten in other number bases and played.
primes, primes-layered, prime-durations	Primes as note indexes and durations.
oeis-midi	Plays any OEIS sequence modulo the number of notes in a scale.
voss-method, voss-method-midi, voss-alteration	Voss's 1/f method from Musimathics (numbers, MIDI, and phrase alteration).
quantum	Note choice via Quantum::Superpositions::Lazy.
play-pixels, play-color-pixels	Hear an image pixel by pixel (grayscale, or one chord per RGB colour).
prolog-music	Scale and note logic expressed in AI::Prolog.

Cellular Automata & Systems

Script	Description
game-of-life-cluster	Runs Conway's Game of Life on a grid of notes with incrementing octaves; each generation's live-cell cluster becomes a chord. Seeded with a glider (a blinker is commented out).
lindenmayer-midi	Applies L-system (Lindenmayer system) rewriting rules, supplied in YAML, to produce MIDI sequences.
midi-turtle.pl	Turtle-graphics-style movement (Data::Turtle) mapped to notes.
cryptomorphic	Voss-driven structure with rhythmic motifs and Music::VoiceGen melodies over drums.
random-walk, random-walk-transform	Random walks over weighted graphs (Graph::Weighted); the second adds atonal transformations.
note-transition, stat-walk	Count note transitions in a MIDI file (saved with Storable), then walk the frequencies to generate new music. -sync variants handle synchronized parts.
synch-weighted, synch-weighted-randomized, synch-oo	Weighted-graph chord and drum generators with synchronized parts.
perm-perm, variations, combi-duras.pl	Permutations, variations and duration combinations.
random-selection, random-selection-mutate	Random population samples compared by Levenshtein distance, then mutated.

Rhythm & Drums

Script	Description
euclidean-beats	Distributes kick and snare onsets using Euclidean rhythm algorithm with prime-number onset counts. Hi-hat plays straight eighths.
euclidean-drums.pl	Real-time Euclidean drum machine for an external MIDI device (args: verbose, port, BPM).
clocked-euclidean-drums.pl	Euclidean drum patterns synchronised to an external MIDI clock.
clocked-euclidean-drum-fills.pl	Adds fills to clocked Euclidean drum patterns.
OMB.pl	One-Man Band: generates randomised hi-hat, kick, and snare patterns plus drum fills using Music::Duration::Partition. Six fill styles descend the tom kit with optional cymbal substitutions.
drum-circle	Multi-part drum circle (has POD usage text).
multi-timbral-drums.py, multi-timbral-drum-fills.pl / .py	Euclidean patterns and snare fills with no clock, for multi-timbral gear.
rand-drums, rand-drums.py, random-beat	Randomised drum parts, and a random pick from all 3-strike eighth-note patterns.
rhythm-necklace, rhythm-chunks	Rhythm necklaces drawn as SVG, and rhythm pieces driven by rhythm-chunks.yml.
tabla, applause.pl, possible-reggae	Tabla patterns, synthesised applause, and a reggae groove.
duration-selection	Explores rhythmic duration selection strategies.
figured-syncopation	Realistic syncopated drum grooves (see the 2023 "realistic drum grooves" write-up).
five-four-durations	Experiments with 5/4 time signatures.
quasi-random-durations, phrase-context, polygenic, oddness, fulfilled	More duration-partition experiments with pitched voices over drums.

Music Theory

Script	Description
all-modes	Prints each chromatic note's seven modes (12 × 7 = 84).
modal-chords, modal-stacked-3rds.pl, mode-pivot	Chords by mode, stacked thirds, and modal pivots (Music::ModalFunction).
which-keys	Brute-forces which keys a given chord belongs to.
all-possible-chords	Enumerates note variations and names each chord (Music::Chord::Namer).
intervals	Large interval/ratio explorer (superseded by the Music::Intervals module).
circle-intervals	Draws SVG diagrams of interval circles around the chromatic scale.
inversion	Names every permutation of a set of notes (mathematical rather than strict musical inversions).
chord-melody	Combines chord voicings with a melody line.
chord-mutate	Chord mutation using Music::ScaleNote.
chordal	Chord-driven composition over drums, built on Music::VoiceGen.
progressive, walk-prog, buzz, voice-gen	Chord progressions with generated voices; walk-prog adds a walking bass.
transformational, transform-chords	Neo-Riemannian chord transformations (Music::Chord::Progression::Transform).
walking-bass	Parses a chord and builds a walking line under guitar-range constraints.
cadences	Generates common cadential patterns.
cadence-logic.pl	Cadence experiments using Math::Logic.
blues-progressions	Blues-jazz progression practice tool, taken from Dan Haerle's chart.
harmonic-entropy.pl	Psychoacoustic harmonic-entropy model.
guidonian	Turns text into melodies using Guido d'Arezzo's method (Music::Guidonian).

Jazz & Real Pieces

Script	Description
blue-monk	Full MIDI transcription of Thelonious Monk's Blue Monk (Bb) from the Real Book, with synchronized drums, walking bass, chord comping, and melody.
mohawk	Charlie Parker's Mohawk with drums, bass and guitar chords.
take-the-a-train	Duke Ellington's Take the "A" Train (Real Book #421).
blue-gene	Blues in the same style with generated bass, guitar chords and voices.
coltrane	Imitates John Coltrane via his circle diagram (see the 2022 write-up).
coltrane-and-company	The same, with added bass and guitar chords.
jingle-bells.pl	Jingle Bells ornamented with Music::MelodicDevice::Ornamentation (plain and fancy .mp3s included; jingle-bells.pod is the Perl Advent article).
in-c	Approximation of Terry Riley's In C.
in-c-randomized	Randomised version of the In C performance practice.
dice-game	Implements Mozart's musical dice game (Musikalisches Würfelspiel).

Bach Choral Analysis

Script	Description
bach-choral	Reads a CSV of Bach choral data (produced by bach-choral.R) and reconstructs melody, chord accompaniment, and bass line as MIDI.
bach-choral-freq	Builds a weighted graph of chord transition frequencies from the chorale data.
bach-choral-network	Builds a network graph of chord transitions via Music::BachChoralHarmony and Graph::Easy.
bach-choral.R	R script to pre-process the Bach choral dataset.

Guitar Tools

Script	Description
fretboard	Draws a guitar fretboard with Imager (superseded by Music::FretboardDiagram).
fretting	Enumerates fingering patterns and flags infractions (backward, span).
fretting-viz	Visualisation of fretting patterns.

MIDI Utilities & Real-Time

Script	Description
capture-midi	Captures incoming MIDI events and sends text or keystrokes to the focused window (e.g. Vim motions).
receive-midi.pl	Receives MIDI and maps notes and velocities using receive-midi.yaml.
clock-gen-async.pl / .py, clock-gen-fritter.py	Async MIDI clock generators (e.g. perl clock-gen-async.pl usb 90).
clock-listener.pl	Listens to an external MIDI clock signal.
midi-control.py	Sends MIDI messages defined in a YAML file.
tk-control.py	Tkinter app that builds those YAML control lists.
simple-control.py, program_change.pl	Minimal control-change and program-change senders.
midi-ports.py	Lists available MIDI ports.
ezd2gm.pl, ezd2gm-choose	Convert single-track EZdrummer MIDI to General MIDI; choose picks files interactively.
midi-simple-dump, gestalt-file	Dump a MIDI file's events, and report pitch/velocity bounds per channel.
ngram-play	Plays the top repeated note phrases of a MIDI file (use this rather than note-ngram-play).
irc-bot	Musical-processing IRC bot (scales, chord names and notes, MP3 tags); see the 2021 write-up.
m21_config.py	Textual TUI for editing music21's settings.

Real-Time MIDI (Perl)

These drive hardware or a software synth through MIDI::RtMidi::FFI::Device, clocked with IO::Async timers. Most take a port-name fragment and a BPM.

Script	Description
clock-listener.pl	Prints incoming MIDI events.
arping.pl, arping2iac.pl	Arpeggiators: one clock for two devices, or an open port (e.g. macOS IAC) with keyboard control.
clocked-euclidean-drums.pl, clocked-euclidean-drum-fills.pl	Euclidean drums, with an outgoing clock.
rt-bassline.pl	Quasi-random walking bass line over "Autumn Leaves" changes.
rtmidi-callback.pl, rtmidi-control.pl, rtmidi-vcv.pl	MIDI::RtController filters, a CC sender, and a VCV Rack controller.
rtmidi-phrase.pl, rtmidi-fuzzix.pl, seq-part-churn.pl	Play a phrase string at a BPM, an async pedal-note experiment, and a program changer every four bars.
SE-02-VolcaDrum.pl, microKorg-VolcaDrum.pl, eurorack-Pams.pl	Rig-specific pitch players on a clock.
volca-drum-cc.pl	Mojolicious::Lite web UI for the Volca Drum's control changes, with saved patches.
trinity-midithing.pl	Euclidean/prime player (its header says it is currently broken).

Real-Time MIDI (Python)

Script	Description
midi-thread-1.py … midi-thread-9.py	An evolving series of threaded generators clocked at 24 PPQN: chords, arpeggios, rhythms and bass, ending with two synths on channels 1 and 2.
multi-timbral.py, multi-timbral-pso-chord.py	Drive a multi-timbral synth, fluidsynth, or a multi-oscillator Eurorack.
midi-Chord2-control.py, midi-wholetone.py, pump-notes.py	Qu-Bit Chord 2 control, a whole-tone generator, and a pitch-list sender.
four-chords.py, hours.py, parts.py, pop-ballad.py	music21 songs built on the author's generator packages.
nx_weights.py, transition.py	NetworkX and music21 transition weights from corpus pieces.

Analysis & Metadata

Script	Description
analyze-recordings, analyze-low-level	AcousticBrainz features as radar charts (see "Led Zeppelin in Seven Dimensions", 2022).
mb-artist-release, www-spotify	MusicBrainz / Cover Art Archive and Spotify lookups.

Configuration Files

File	Description
capture-midi.yaml	MIDI capture configuration.
midi-rock-stone-SE-02.yaml, se-02.yaml	Studio Electronics SE-02 synthesiser MIDI maps.
midi-rock-stone-microKORG.yaml	Korg microKORG MIDI map.
midi-rock-stone.yaml, midi-rock-stone-midi-thing.yaml, midi-thing-v2.yaml	Controller maps for the Rock-Stone / MIDI Thing.
receive-midi.yaml, rhythm-chunks.yml	Inputs for receive-midi.pl and rhythm-chunks.

Subdirectories

Directory	Description
clock/	External-device clock demos: clocked-drums.pl, clocked-drums-3.pl, clock-drums.py, clock-gen.py.
cmmwp/	cmmwp-1.pl … cmmwp-9.pl: nine progressively richer MIDI::Util examples, from a quarter-note loop to rhythmic phrases with voices.
mrwmip/	"Musical Rhythms with Math in Python": music-and-math.md, coder-legion-*.py (partitions, necklaces, Euclidean), perldotcom-*.pl, and rendered .mp3s.
perl.com/	Code for perl.com articles: arpeggios.pl, little-drummer.pl, euclidean-drummer.pl, with sample .mid / .mp3 files.
tones/	tones-*.pl: progressive real-time tonal MIDI examples.

---

Getting Started

Prerequisites

Install the required Perl modules via CPAN or cpanm:

cpanm MIDI::Util MIDI::Drummer::Tiny Music::Duration::Partition \
      Music::CreatingRhythms Music::AtonalUtil Music::Chord::Note \
      Music::Note Music::Scales Music::VoiceGen Music::Cadence \
      AI::Genetic Game::Life Math::Utils Math::Prime::XS

For Python scripts:

pip install mido python-rtmidi music21 pychord networkx numpy pyyaml

Running a Script

Offline scripts write a .mid file to the current directory named after the script ($0.mid). Real-time scripts take a MIDI port-name fragment instead (list ports with python3 midi-ports.py). Run them directly:

perl euclidean-beats          # generates euclidean-beats.mid
perl blue-monk                # generates blue-monk.mid
perl lorenz-attractor.pl      # generates lorenz-attractor.pl.mid + .csv
python3 mandelbrot_music.py   # generates MIDI output

Many scripts accept positional arguments to control parameters such as BPM, bar count, or loop count:

perl euclidean-beats 16 8 90 100   # terms, loops, BPM, volume (these are the defaults)
perl OMB.pl 120 4 4                # BPM, motif length in quarter notes, repeats

Open the resulting .mid file in any DAW, MIDI player, or notation software (e.g. GarageBand, MuseScore, Logic Pro, Ableton).

---

Status Notes

• Superseded: fretboard (by Music::FretboardDiagram), intervals (by Music::Intervals), note-ngram-play (by ngram-play).
• Moved: solitude now lives in the Music-Bassline-Generator repository.
• Broken: trinity-midithing.pl (per its header); string-blender depends on the broken String::Blender.
• Helper only: voicegen.pl is called by random-rhythms.py.

Modern Perl Notes

Of the ~150 Perl programs, only 25 declare a modern version (23 use v5.36, 2 use v5.40); most use plain use strict.

• Replace use strict; use warnings; with use v5.36; (adds say and signatures).
• rtmidi-vcv.pl has no use strict at all.
• random-selection has a typo shebang (#!usr/bin/env perl, missing the leading slash); fretboard and fretting use #!/usr/bin/perl.
• multi-timbral-drum-fills.pl uses Try::Tiny (use feature 'try' on 5.34+), and random-walk-transform uses Readonly (use constant).
• About 14 scripts still use the legacy MIDI::Simple; newer ones use MIDI::Util::setup_score or MIDI::Drummer::Tiny.

use v5.40;
sub add_bar ($score, $pitch) { $score->n('wn', $pitch) }

---

License

This project is licensed under the Artistic License 2.0.