midi-sketch

A C++17 library for auto-generating pop music MIDI sketches. Designed for WebAssembly deployment with zero external dependencies.

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Live Demo | Documentation

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Features

• 8 Track Output: Vocal, Chord, Bass, Motif, Arpeggio, Aux, Drums, SE
• Rich Presets: Structure (18) × StylePreset (17) × Mood (20) × Chord Progression (22)
• Advanced Melody: Phrase-based generation, HookIntensity, MelodicComplexity, VocalStyleProfile
• Music Theory: Voice leading, non-chord tones, chord extensions, dynamic velocity
• Composition Styles: MelodyLead, BackgroundMotif, SynthDriven
• Deterministic: Seed-based reproducible generation

Build

make build              # Native build
make test               # Run tests
./build/bin/midisketch_cli  # Generate output.mid

# WASM build (requires Emscripten)
source ~/emsdk/emsdk_env.sh && make wasm

Quick Example

C++ API

#include "midisketch.h"

midisketch::MidiSketch sketch;
midisketch::GeneratorParams params;
params.structure_id = 1;   // BuildUp (0-17)
params.mood_id = 0;        // StraightPop (0-19)
params.chord_id = 0;       // Canon progression (0-21)
params.seed = 12345;

sketch.generate(params);
auto midi = sketch.getMidi();       // SMF binary

JavaScript / TypeScript (WASM)

import { init, MidiSketch } from '@libraz/midi-sketch';

await init();
const sketch = new MidiSketch();

sketch.generate({
  structureId: 1,
  moodId: 0,
  chordId: 0,
  seed: 12345
});

const midiData = sketch.getMidi();  // Uint8Array
sketch.destroy();

Output Tracks

Track	Channel	Program	Purpose
Vocal	0	Piano	Melody
Chord	1	E.Piano	Chords
Bass	2	E.Bass	Bass line
Motif	3	Synth Lead	Background
Arpeggio	4	Saw Lead	Arpeggio
Aux	5	Warm Pad	Sub-melody
Drums	9	-	GM Drums
SE	15	-	Markers

Documentation

• Getting Started
• API Reference (JavaScript)
• API Reference (C++)
• Presets
• Track Generators
• Architecture
• CLI Reference

License

This project is dual-licensed:

• Open Source: Apache License 2.0 - For evaluation, research, and non-commercial use
• Commercial: Commercial License - For closed-source, proprietary, or SaaS use

Which License Do I Need?

Use Case	License
Evaluation / Research	Apache-2.0 (free)
Non-commercial use	Apache-2.0 (free)
Closed-source product	Commercial (paid)
Commercial SaaS	Commercial (paid)

For commercial licensing inquiries: libraz@libraz.net

Scope Notice

This project provides a core engine, not a complete music generation system.

Sound sources, vocals, and rendering are out of scope.

Author

libraz libraz@libraz.net