Chord Analyzer

An Ableton Live Extension that extracts chord progressions from MIDI clips and displays them as copyable text — ready to paste into Claude for arrangement analysis.

What it does

Right-click any MIDI clip → 「コード進行を解析」 → a dialog shows the chord progression per bar, with note names and chord symbols. Hit "クリップボードにコピー" and paste it wherever you need it.

Example output:

Track: Atmosphere Pad
BPM: 138
Clip: 1-Chord Loop

Bar 1:     Bm       (B D F#)
Bar 5:     G        (G B D)
Bar 9:     D        (D F# A)
Bar 13:    A        (A C# E)

Requirements

• Ableton Live 12.4.5 Suite Beta (or later with Extensions support)
• Node.js ≥ 24 (managed via fnm)

Development

Setup

npm install

Run (development mode)

1. Open Live and enable Preferences → Extensions → Developer Mode
2. In PowerShell:

$fnmEnv = & fnm env --shell powershell; Invoke-Expression ($fnmEnv -join "`n")
npm start

Live will show the context menu action on any MIDI clip. Restart npm start after code changes.

Build

npm run build:dev   # development build (with sourcemaps)
npm run build       # production build

Package for installation

npm run package     # produces chord-analyzer.ablx

Drop the .ablx file into Preferences → Extensions in Live to install it permanently (no npm start needed).

Chord detection

Notes are grouped by bar (4 beats, 4/4 assumed). Supported chord types:

Suffix	Type
(none)	Major
m	Minor
5	Power chord
dim	Diminished
aug	Augmented
sus2 / sus4	Suspended
maj7	Major 7th
7	Dominant 7th
m7	Minor 7th
mM7	Minor Major 7th
dim7	Diminished 7th
m7b5	Half-diminished
6 / m6	6th
add9	Add 9

If no pattern matches, the pitch class names are shown as-is (e.g. C/E/G/Bb).

Project structure

src/
  extension.ts    — main extension logic
  interface.html  — modal dialog UI
  html.d.ts       — TypeScript declaration for HTML imports
manifest.json     — extension metadata
build.ts          — esbuild build script
.env              — EXTENSION_HOST_PATH (not committed)