🎹 MidiBox

An always-on MIDI recording service that captures every note played on your keyboard, letting you save, label, and play back your practice sessions.

Overview

MidiBox runs as a background service on a small computer (like an Alpine Linux box) connected to your MIDI keyboard. It continuously records all MIDI events to a local SQLite database, providing:

• Real-time visualization of notes as they're played on a virtual piano
• Session labeling via a mobile-friendly web interface
• Playback of recorded sessions back to the keyboard
• MIDI file import to play standard .mid files on your keyboard

Perfect for musicians who want to capture spontaneous practice moments without remembering to hit "record."

Current Features

✅ Implemented

• Continuous MIDI capture from raw MIDI devices (/dev/snd/midiC*D*)
• SQLite storage using Bun's built-in bun:sqlite for efficient event storage
• Web UI (port 4000) with:
  • Live 88-key piano visualization (A0-C8)
  • Real-time event log showing notes, velocities, and control changes
  • Session management (save/load named sessions with performer and song info)
  • MIDI output selection for playback
  • Click/touch-to-play keys (plays notes on the keyboard)
  • MIDI file upload and playback
  • Playback progress bar with green key highlighting
• TUI client for HDMI-connected displays (connects via WebSocket)
• OpenRC service scripts for Alpine Linux deployment
• WebSocket streaming for real-time updates to all connected clients

🚧 Planned Features

• Automatic song detection - Analyze gaps in playing to automatically identify when songs start and end
• Timeline visualization - Visual waveform/piano roll view of recorded data showing note density over time
• Timeline scrubbing - Navigate through hours of recorded data with a visual scrubber
• Manual session selection - Draw on the timeline to select time spans for marking as sessions
• Smart segmentation - AI-assisted suggestions for song boundaries based on tempo, key changes, and pauses
• Export options - Export sessions as MIDI files or audio
• Quantization - Snap recorded notes to a grid (1/4, 1/8, 1/16 notes, etc.) to clean up timing
• Sheet music PDF generation - Quantize recordings and generate printable PDF sheet music with proper notation

Tech Stack

• Runtime: Bun
• Database: SQLite via bun:sqlite
• MIDI: Raw device access (/dev/snd/midi*)
• Frontend: Vanilla HTML/CSS/JS with WebSocket
• Target OS: Alpine Linux with OpenRC

Installation

# Clone the repository
git clone https://github.com/creationix/midibox.git
cd midibox

# Install dependencies
bun install

# Start the server
bun run start

Usage

1. Connect your MIDI keyboard
2. Start the MidiBox server: bun run start
3. Open http://localhost:4000 in a browser
4. Play your keyboard - notes appear on the virtual piano in real-time
5. Use the session panel to save and label recordings

Service Installation (Alpine Linux)

# Copy service scripts
sudo cp scripts/midibox /etc/init.d/
sudo chmod +x /etc/init.d/midibox

# Enable and start
sudo rc-update add midibox default
sudo rc-service midibox start

API Endpoints

Method	Endpoint	Description
GET	/api/events/recent?minutes=5	Get recent MIDI events
GET	/api/events/range?start=&end=	Get events in time range
GET	/api/sessions	List all sessions
POST	/api/sessions	Create a new session
GET	/api/midi/inputs	List MIDI input devices
GET	/api/midi/outputs	List MIDI output devices
POST	/api/playback/start	Start session playback
POST	/api/playback/stop	Stop playback
POST	/api/playback/file	Upload and play MIDI file
WS	/ws	WebSocket for real-time events

License

MIT