itshellbound/juce-plugin-template

JUCE VST Plugin Development Kit

Complete setup for VST plugin development with JUCE framework, including an MCP server for documentation access.

Contents

1. mcp-server/ - Model Context Protocol server for JUCE documentation
2. juce-template/ - Ready-to-use JUCE plugin template

Part 1: MCP Server for JUCE Documentation

The MCP server provides access to JUCE documentation and code generation tools directly in Claude Code.

Setup MCP Server

cd mcp-server
npm install

Configure Claude Desktop

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "juce-docs": {
      "command": "node",
      "args": ["/Users/hellbound/juce-mcp-project/mcp-server/index.js"]
    }
  }
}

Available Resources

• juce://docs/getting-started - JUCE framework introduction
• juce://docs/audio-processor-basics - AudioProcessor fundamentals
• juce://docs/dsp-basics - DSP module guide
• juce://docs/parameters - Parameter management
• juce://templates/basic-plugin - Plugin template structure

Available Tools

• search_juce_docs - Search JUCE documentation
• generate_plugin_code - Generate boilerplate code (processor, editor, parameters, dsp-chain)
• explain_juce_concept - Get detailed explanations of JUCE concepts

Part 2: JUCE Plugin Template

A complete, production-ready VST plugin template with modern JUCE architecture.

Features

• ✅ AudioProcessor with DSP chain
• ✅ AudioProcessorValueTreeState for parameter management
• ✅ Custom AudioProcessorEditor with GUI
• ✅ Input/Output gain controls
• ✅ State save/load functionality
• ✅ Stereo/Mono support
• ✅ Clean, commented code

Project Structure

juce-template/
├── PluginProcessor.h      # Audio processing header
├── PluginProcessor.cpp    # Audio processing implementation
├── PluginEditor.h         # GUI header
└── PluginEditor.cpp       # GUI implementation

Using the Template

Option 1: Create New Projucer Project

1. Open Projucer
2. Create new Audio Plug-In project
3. Replace PluginProcessor.h/cpp and PluginEditor.h/cpp with template files
4. Configure plugin formats (VST3, AU, AAX)
5. Save and open in your IDE

Option 2: Add to Existing Project

1. Copy template files to your project's Source/ directory
2. Rename classes from CustomPlugin* to your plugin name
3. Update #include statements
4. Add to Projucer and save

Key Components

AudioProcessor (PluginProcessor.cpp)

• prepareToPlay() - Initialize DSP with sample rate and buffer size
• processBlock() - Main audio processing loop
• createParameterLayout() - Define plugin parameters
• getStateInformation() - Save plugin state
• setStateInformation() - Restore plugin state

AudioProcessorEditor (PluginEditor.cpp)

• Constructor - Create and configure UI components
• paint() - Custom graphics and styling
• resized() - Layout UI components

Customization Guide

Adding Parameters

In PluginProcessor.cpp, add to createParameterLayout():

params.push_back(std::make_unique<juce::AudioParameterFloat>(
    "cutoff",
    "Cutoff Frequency",
    juce::NormalisableRange<float>(20.0f, 20000.0f, 1.0f, 0.3f),
    1000.0f,
    "Hz"
));

Adding DSP Processors

In PluginProcessor.h:

private:
    juce::dsp::StateVariableTPTFilter<float> filter;
    juce::dsp::Reverb reverb;

In prepareToPlay():

filter.prepare(spec);
reverb.prepare(spec);

In processBlock():

filter.process(context);
reverb.process(context);

Adding UI Controls

In PluginEditor.h:

private:
    juce::Slider cutoffSlider;
    juce::Label cutoffLabel;
    std::unique_ptr<juce::AudioProcessorValueTreeState::SliderAttachment> cutoffAttachment;

In PluginEditor.cpp constructor:

cutoffSlider.setSliderStyle(juce::Slider::RotaryHorizontalVerticalDrag);
addAndMakeVisible(cutoffSlider);

cutoffAttachment = std::make_unique<juce::AudioProcessorValueTreeState::SliderAttachment>(
    audioProcessor.getAPVTS(), "cutoff", cutoffSlider
);

Building Your Plugin

1. Open project in Projucer
2. Set plugin formats (VST3, AU, AAX)
3. Configure company name and plugin ID
4. Export to IDE (Xcode, Visual Studio, etc.)
5. Build in your IDE

Plugin Formats

The template supports:

• VST3 - Cross-platform (Windows, macOS, Linux)
• AU (Audio Unit) - macOS only
• AAX - Pro Tools (requires AAX SDK)
• Standalone - Desktop application

Development Workflow

With MCP Server

1. Start Claude Desktop with MCP server configured
2. Use search_juce_docs tool to find documentation
3. Use generate_plugin_code to create components
4. Use explain_juce_concept for detailed explanations

Testing

1. Build plugin in your IDE
2. Copy to plugin folder:
   • macOS VST3: ~/Library/Audio/Plug-Ins/VST3/
   • macOS AU: ~/Library/Audio/Plug-Ins/Components/
   • Windows VST3: C:\Program Files\Common Files\VST3\
3. Open in DAW (Ableton, Logic, Reaper, etc.)
4. Test audio processing and UI

Resources

• JUCE Documentation
• JUCE Forum
• JUCE GitHub
• JUCE Tutorials

Troubleshooting

MCP Server Issues

• Ensure Node.js is installed: node --version
• Check Claude Desktop config path is correct
• Restart Claude Desktop after config changes
• Check logs in Claude Desktop for errors

Build Issues

• Verify JUCE path in Projucer
• Check C++ standard is C++17 or higher
• Ensure all modules are enabled (juce_audio_processors, juce_dsp, etc.)
• Update JUCE to latest version

Plugin Not Appearing in DAW

• Check plugin was copied to correct directory
• Rescan plugins in DAW
• Check plugin validation (macOS: auval -a, Windows: Plugin validation in DAW)
• Ensure architecture matches DAW (x86_64 vs arm64)

License

Template code is provided as-is for educational and commercial use.

JUCE framework has its own licensing terms - check juce.com for details.