Audio Interface JACK Starter (ai-jack-starter)

Automatic JACK audio server management for USB audio interfaces. Starts and stops JACK based on hardware detection and user login status. Works with any JACK-compatible audio interface.

Features

• Automatic JACK start/stop when audio interface is connected/disconnected
• Hot-plug support - connect your interface anytime, JACK starts automatically
• Boot detection - JACK starts after login if interface is already connected
• Device auto-detection - GUI detects all connected audio devices
• Flexible JACK configuration - customize sample rate, buffer size, and periods
• Optional A2J MIDI bridge - control ALSA-to-JACK MIDI bridge (disabled by default for modern DAWs)
• GTK3 GUI for easy configuration with live latency calculation
• Quick presets - Low, Medium, and Ultra-Low latency with one click
• Passwordless operation via polkit for audio group members

Supported Audio Interfaces

Works with any JACK-compatible USB audio interface. Devices are auto-detected - no manual configuration needed!

Tested with:

• MOTU M4
• Focusrite Scarlett Solo/2i2
• Steinberg UR242
• RME Babyface Pro
• Native Instruments Komplete Audio
• Any USB Audio Class compliant device

Quick Start

# 1. Clone the repository
git clone https://github.com/giang17/ai-jack-starter.git
cd ai-jack-starter

# 2. Run the installer (installs everything)
sudo ./install.sh

# 3. Done! Your audio device is auto-detected.
#    Optional: Open the GUI to adjust JACK settings:
ai-jack-gui.py

The installer automatically:

• Installs all scripts, UDEV rules, GUI, polkit rules, and systemd services
• Audio devices are auto-detected at runtime - no manual configuration needed
• Hot-plug support: connect any USB audio interface and JACK starts automatically

For manual installation, see INSTALL.md.

Device Configuration

Audio devices are auto-detected! Simply connect your USB audio interface and JACK will start automatically.

Configuration File (Optional)

The config file /etc/ai-jack/jack-setting.conf stores JACK audio parameters:

# JACK Settings (device is auto-detected)
JACK_RATE=48000
JACK_PERIOD=256
JACK_NPERIODS=2

# Optional
A2J_ENABLE=false

Use the GUI to change settings - it's easier than editing the config file manually.

JACK Configuration

Flexible Configuration (v3.0)

Configure any combination of sample rate, buffer size, and periods:

# Custom configuration (device is auto-detected)
sudo ai-jack-setting-system.sh --rate=96000 --period=128 --nperiods=2 --restart

# Show current configuration
sudo ai-jack-setting-system.sh current

# Show all options
sudo ai-jack-setting-system.sh help

Valid Values

Parameter	Valid Values
Sample Rate	22050, 44100, 48000, 88200, 96000, 176400, 192000 Hz
Buffer Size	16, 32, 64, 128, 256, 512, 1024, 2048, 4096 frames
Periods	2 - 8

Quick Presets

For convenience, presets are still available:

Preset	Sample Rate	Buffer	Periods	Latency	Use Case
1 - Low	48 kHz	128	2	~5.3 ms	General audio work
2 - Medium	48 kHz	256	2	~10.7 ms	Stable, recommended
3 - Ultra-Low	48 kHz	64	2	~2.7 ms	Optimized systems only

# Use preset (legacy syntax still works)
sudo ai-jack-setting-system.sh 2 --restart

Latency Calculation

Latency (ms) = (Buffer Size × Periods) / Sample Rate × 1000

ALSA-to-JACK MIDI Bridge

The GUI includes a toggle for the ALSA-to-JACK MIDI bridge (a2jmidid):

Default: disabled - Recommended for modern DAWs like Bitwig Studio and Reaper, which access ALSA MIDI directly and may show "device busy" errors when a2jmidid is running.

Enable it if you:

• Use hardware MIDI controllers that only appear in ALSA
• Need MIDI routing within JACK (visible in Patchance/Carla)
• Use older software that expects JACK MIDI ports

How to use:

1. Open the GUI (ai-jack-gui.py)
2. Check/uncheck "Enable ALSA-to-JACK MIDI Bridge"
3. Click "Apply"

When enabled, the bridge uses --export-hw flag to keep hardware ports available for both JACK and ALSA applications.

GUI

Start the GUI via terminal or application menu:

ai-jack-gui.py

Or find it in: Audio/Video → Audio Interface JACK Settings

GUI Features

• Auto-detection - Automatically detects connected USB audio interfaces
• Device dropdown - Select from detected audio interfaces (if multiple connected)
• Sample Rate dropdown - Select from 22050 Hz to 192000 Hz
• Buffer Size dropdown - Select from 16 to 4096 frames
• Periods spinner - Adjust from 2 to 8 periods
• Live latency calculation - See latency update as you change settings
• Quick preset buttons - One-click Low, Medium, Ultra-Low latency
• Status monitoring - JACK server and hardware connection status
• Auto-restart option - Apply changes and restart JACK immediately

Documentation

See INSTALL.md for:

• Detailed installation instructions
• Configuration options
• Troubleshooting guide
• Technical details

Requirements

• Ubuntu Studio 24.04+ (or any Linux with JACK support)
• USB Audio Interface (any JACK-compatible device)
• JACK2 with DBus support (or Pipewire with JACK compatibility)
• Python 3 + GTK3 (for GUI)

Migration from motu-m4-jack-starter

If you have an existing motu-m4-jack-starter installation, the installer will:

1. Detect old installation files
2. Offer to remove them
3. Optionally migrate your configuration

Your JACK settings will be preserved during migration.

Changelog

See CHANGELOG.md for detailed version history.

For release notes with download links, see GitHub Releases.

License

GPL-3.0-or-later - See LICENSE

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Status: Production Ready