Beater - Drum Machine

A JACK-aware drum machine with timeline-based pattern arrangement for Linux.

Features

• 🎵 JACK Audio Integration - Real-time low-latency drum playback
• 🎨 Interactive Timeline Editor - Drag, drop, resize regions with snap-to-grid
• 📊 Pattern Library - Groove, fill, and half-time patterns
• 🎼 Dynamic Time Signatures - Right-click regions to change time signature
• ⏱️ Tempo Control - 40-300 BPM with real-time adjustment
• 🔍 Zoom Controls - Mouse wheel zoom (Ctrl+scroll) and toolbar buttons
• ⌨️ Keyboard Shortcuts - Delete key to remove regions, standard shortcuts
• 💾 Project Persistence - Save/load projects in JSON format (.beater files)
• 🎚️ Transport Controls - Play, stop, rewind with visual playhead
• 🌍 Cross-Platform Sample Detection - Automatically finds samples in common locations
• 🎨 Dark Theme UI - Professional modern interface
• 📍 Playhead Control - Click to position, drag to scrub

Installation

Quick Start (Binary)

Download the latest release from Releases:

# Download and extract
wget https://github.com/applebiter/beater/releases/download/v0.1.0/beater
chmod +x beater

# Install dependencies
sudo apt install jackd2 qjackctl libqt6widgets6 libsndfile1

# Start JACK (use qjackctl or command line)
qjackctl &

# Run Beater
./beater

Building from Source

Dependencies

# Ubuntu/Debian
sudo apt-get install build-essential cmake git \
    libjack-jackd2-dev libsndfile1-dev \
    qt6-base-dev libqt6widgets6

# Arch Linux
sudo pacman -S base-devel cmake git jack2 libsndfile qt6-base

Compile

git clone https://github.com/applebiter/beater.git
cd beater
mkdir build
cd build
cmake ..
make -j$(nproc)

Run

# Start JACK first
qjackctl &

# Run from build directory
./src/beater

Usage

Getting Started

1. Start JACK - Use qjackctl or start JACK manually
2. Launch Beater - The application will auto-detect drum samples
3. Drag Patterns - Drag pattern blocks from the palette to the timeline
4. Edit Timeline - Click, drag, resize, and delete regions
5. Change Time Signatures - Right-click regions to set custom time signatures
6. Adjust Tempo - Use the tempo spinbox or type a value
7. Play/Stop - Use transport controls or spacebar
8. Save Projects - File → Save (Ctrl+S)

Keyboard Shortcuts

• Ctrl+N - New project
• Ctrl+O - Open project
• Ctrl+S - Save project
• Ctrl+Shift+S - Save As
• Ctrl+, - Settings
• Delete or Backspace - Delete selected region
• Ctrl+Scroll - Zoom timeline

Sample Configuration

Beater automatically searches for drum samples in:

• /usr/share/hydrogen/data/drumkits/GMRockKit/
• /usr/local/share/hydrogen/data/drumkits/GMRockKit/
• ~/.hydrogen/data/drumkits/GMRockKit/
• ./samples/ (relative to executable)

To add custom sample directories: File → Settings

Project File Format

Projects are saved as JSON files with .beater extension:

{
  "version": 1,
  "name": "My Project",
  "patterns": [...],
  "tracks": [...],
  "instruments": [...],
  "meterChanges": [...]
}

Architecture

beater/
├── src/
│   ├── domain/          # Core data structures
│   │   ├── TimeTypes    # Musical time, tempo, meter
│   │   ├── Pattern      # Note sequences
│   │   ├── Region       # Timeline blocks
│   │   ├── Track        # Arrangement lanes
│   │   ├── Instrument   # Sample mapping
│   │   └── Project      # Top-level document
│   ├── engine/          # Audio processing
│   │   ├── JackAudioBackend  # JACK integration
│   │   ├── Sampler      # Sample playback
│   │   ├── Scheduler    # Event scheduling
│   │   └── Transport    # Playback control
│   ├── ui/              # Qt6 interface
│   │   ├── MainWindow   # Main application window
│   │   ├── TimelineWidget    # Timeline editor
│   │   └── PatternPalette    # Pattern library
│   ├── serialization/   # JSON save/load
│   └── app/             # Main entry point
├── tests/               # Unit tests
└── external/            # Third-party dependencies (nlohmann/json)

Technical Details

• Language: C++17
• UI Framework: Qt6 (6.4.2+)
• Audio Backend: JACK Audio Connection Kit
• Build System: CMake 3.16+
• Sample Loading: libsndfile
• Serialization: nlohmann/json
• Time Resolution: 960 PPQ (Pulses Per Quarter note)

Troubleshooting

"Failed to load samples"

• Install Hydrogen drum machine: sudo apt install hydrogen
• Or configure custom sample directories in Settings

JACK Connection Issues

• Ensure JACK is running: jack_lsp should list ports
• Check JACK settings in qjackctl (try 48000 Hz, 256 frames)
• Verify Beater appears in JACK connections

Qt6 Not Found

• Ubuntu 22.04+: sudo apt install qt6-base-dev
• Older Ubuntu: Add Qt6 PPA or build from source

Contributing

Contributions welcome! Areas for improvement:

• Windows/Mac audio backend support
• Additional pattern types
• MIDI I/O
• LV2 plugin hosting
• Improved sample management

License

MIT License - see LICENSE file for details.

Free to use, modify, and distribute.

Credits

• Inspired by Hydrogen Drum Machine
• Uses JACK Audio Connection Kit
• Qt6 framework for UI

Links

• GitHub: https://github.com/applebiter/beater
• Issues: https://github.com/applebiter/beater/issues
• Releases: https://github.com/applebiter/beater/releases

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Note: This is an early release focused on Linux with JACK. Windows/Mac support and additional features are planned for future releases.