Getting Started

MIDI Sketch is a lightweight library for auto-generating pop music MIDI sketches. It runs entirely in the browser using WebAssembly.

Quick Start

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

// Initialize the WASM module
await init()

// Create an instance
const sketch = new MidiSketch()

// Create a config for a style preset (0 = first style)
const config = createDefaultConfig(0)

// Customize as needed
config.key = 0           // Key (0 = C)
config.bpm = 120         // Tempo (0 = use style default)
config.seed = 12345      // Random seed (0 = random)

// Generate MIDI
sketch.generateFromConfig(config)

// Get the MIDI data
const midiData = sketch.getMidi()

// Download the file
downloadMidi(midiData, 'my-song.mid')

What It Generates

MIDI Sketch generates multi-track MIDI files with:

Track	Channel	Description
Vocal	0	Main melody line (piano roll-safe)
Aux	5	Sub-melody support (pulse loops, groove accents)
Chord	2	Harmonic backing with voice leading
Bass	3	Bass line with approach notes
Drums	9	Rhythm patterns with fills (GM drums)
Motif	4	Background patterns (BackgroundMotif style)
Arpeggio	5	Synth arpeggios (SynthDriven style)
SE	15	Section markers

Track Availability

Not all tracks are generated for every style:

• Motif track: Only in BackgroundMotif composition style
• Arpeggio track: Only when arpeggioEnabled: true (must be explicitly enabled, even in SynthDriven style)
• Vocal/Aux: Can be skipped with skipVocal: true for BGM-only generation

Next Steps

• Installation - Install the library
• JavaScript API - JavaScript/WASM API documentation
• C++ API - C++/C API documentation