JUCE Gain & Pitch Shift Audio Plugin

A simple audio plugin built with the JUCE framework that applies gain control and real-time pitch shifting to incoming audio. The plugin includes a minimal graphical interface with sliders for adjusting volume and pitch.

This project demonstrates the basic structure of a JUCE plugin, including:

• Audio processing (AudioProcessor)
• Graphical user interface (AudioProcessorEditor)
• Real-time DSP inside processBlock

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Features

🎚 Gain Control

Adjust the output volume of the audio signal using a vertical slider.

Range:

0.0 → 1.0

The gain is applied directly to the incoming audio buffer.

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🎵 Pitch Shifting

The plugin can shift the pitch of incoming audio up or down.

Range:

-12 semitones → +12 semitones

Examples:

Pitch	Effect
+12	One octave up
+7	Perfect fifth up
-12	One octave down

The pitch shifting is implemented using a simple resampling method with linear interpolation.

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How It Works

The plugin processes audio in blocks using JUCE’s processBlock() function.

Processing steps:

Incoming Audio
      ↓
Apply Gain
      ↓
Resample Audio (Pitch Shift)
      ↓
Output Audio

Pitch shifting is achieved by computing a pitch ratio:

pitchRatio = 2^(semitones / 12)

For example:

+12 semitones → pitchRatio = 2

The algorithm then reads samples from earlier positions in the audio buffer and interpolates between them to generate the shifted pitch.

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Graphical Interface

The plugin editor contains two vertical sliders:

Slider	Function
Gain	Controls output volume
Pitch	Shifts pitch in semitones

When a slider is moved, the GUI sends the updated value to the audio processor.

Example:

slider → audioProcessor.mGain
slider → audioProcessor.mPitch

These parameters are then used inside the audio processing function.

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Project Structure

JUCE-PitchShift-Plugin
│
├── PluginProcessor.h
├── PluginProcessor.cpp
│     Core audio processing code
│
├── PluginEditor.h
├── PluginEditor.cpp
│     Graphical interface (sliders)
│
└── README.md

PluginProcessor

Handles:

• audio input/output
• DSP processing
• gain and pitch calculations

PluginEditor

Handles:

• GUI layout
• slider controls
• user interaction

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Building the Plugin

This project requires the JUCE framework.

Steps:

1. Install JUCE.
2. Open the project in Projucer or your IDE.
3. Build the project for your target format (VST3, AU, etc.).

Supported plugin formats depend on your JUCE configuration.

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Running the Plugin

1. Build the plugin.
2. Load it into a Digital Audio Workstation (DAW), such as:

• Ableton Live
• Logic Pro
• Reaper
• FL Studio

3. Insert the plugin on an audio track.
4. Adjust the sliders to change the gain and pitch of the audio signal.

License

This project is intended for educational and experimental use. Feel free to modify and extend it.