🎛️ Spectral Morpher

A real-time spectral morphing VST3/AU plugin built with JUCE

Freeze, shift, tilt, and morph audio in the frequency domain — in real time.

---

Overview

Spectral Morpher processes audio using a phase vocoder / STFT pipeline, giving you direct access to the frequency-domain representation of sound. Instead of working with samples, it works with spectral bins — enabling effects that are impossible with traditional time-domain processing.

Input Audio
    │
    ▼
Overlap-Add STFT (2048-pt FFT · 75% overlap · Hann window)
    │
    ├── Spectral Freeze   — lock a frame as a sustained drone
    ├── Spectral Shift    — translate bins ±24 semitones
    ├── Spectral Tilt     — log-frequency slope EQ
    ├── Harmonic Enhancer — fold energy into 2× bins
    └── Morph Accumulator — peak-hold spectral smear with decay
    │
    ▼
Phase Vocoder Reconstruction → Overlap-Add IFFT → Output

---

Parameters

Parameter	Range	Description
Morph	0–100%	Spectral peak-hold accumulator. At 0% = clean. At 100% = infinite spectral sustain / bloom
Shift	±24 st	Moves all spectral bins up or down in frequency, independent of pitch
Freeze	on/off	Locks the current FFT snapshot — converts any transient into a held drone
Tilt	±100%	Spectral slope EQ applied in frequency domain. Positive = bright, negative = warm
Harmonics	0–100%	Folds energy from bin k into bin 2k, adding soft even-harmonic saturation
Mix	0–100%	Dry/wet blend
Gain	−24 to +12 dB	Output level

Creative patches

Patch	Settings
Spectral reverb tail	Morph 70%, Mix 60%, Tilt −20%
Drone from any hit	Freeze ON, Harmonics 40%, Mix 100%
Alien pitch shift	Shift +7st, Morph 30%, Harmonics 20%
Warm spectral smear	Morph 50%, Tilt −40%, Shift −3st
Air and sheen	Harmonics 80%, Tilt +30%, Morph 10%

---

Building

Prerequisites

Tool	Version
CMake	3.22+
C++ compiler	C++17 (Clang 12+, MSVC 2019+, GCC 11+)
JUCE	7.x or 8.x

1 — Clone with submodule

git clone https://github.com/YOUR_USERNAME/SpectralMorpher.git
cd SpectralMorpher
git submodule update --init --recursive

No JUCE submodule? Pass -DJUCE_DIR=/path/to/JUCE to CMake instead.

2 — Configure

mkdir build && cd build

# macOS — Apple Silicon (recommended)
cmake .. -G Ninja \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_OSX_ARCHITECTURES="arm64" \
  -DCMAKE_OSX_DEPLOYMENT_TARGET="12.0"

# macOS — Universal Binary (arm64 + x86_64)
cmake .. -G Ninja \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_OSX_ARCHITECTURES="arm64;x86_64" \
  -DCMAKE_OSX_DEPLOYMENT_TARGET="12.0"

# Windows
cmake .. -G "Visual Studio 17 2022" -A x64

# Linux
cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release

3 — Build

cmake --build . --config Release --parallel

4 — Output locations

Platform	Path
macOS VST3	build/SpectralMorpher_artefacts/Release/VST3/SpectralMorpher.vst3
macOS AU	build/SpectralMorpher_artefacts/Release/AU/SpectralMorpher.component
Windows VST3	build\SpectralMorpher_artefacts\Release\VST3\SpectralMorpher.vst3
Linux VST3	build/SpectralMorpher_artefacts/Release/VST3/SpectralMorpher.vst3

---

Installation

macOS

# VST3
cp -r build/**/*.vst3 ~/Library/Audio/Plug-Ins/VST3/

# AU
cp -r build/**/*.component ~/Library/Audio/Plug-Ins/Components/

Gatekeeper: On first load macOS may block the plugin. Go to System Settings → Privacy & Security and click Allow. For Ableton Live on Apple Silicon: right-click the .vst3 → Get Info → uncheck Open with Rosetta.

Windows

Copy SpectralMorpher.vst3 to C:\Program Files\Common Files\VST3\, then rescan in your DAW.

---

DAW Setup

Ableton Live

1. Preferences → Plug-ins → VST3 Plug-in Folder — set to ~/Library/Audio/Plug-Ins/VST3/
2. Enable AU Plug-ins on macOS (recommended over VST3 for stability in Live)
3. Click Rescan
4. Browse to Plug-ins → SpectralMorpher and drag onto an Audio track

Logic Pro

Build the AU format (macOS only). Copy the .component to ~/Library/Audio/Plug-Ins/Components/. Logic auto-scans on launch — plugin appears under Audio FX → YOUR_STUDIO → Spectral Morpher.

Reaper / Bitwig / Cubase

Point your DAW's VST3 scan path to ~/Library/Audio/Plug-Ins/VST3/ (macOS) or C:\Program Files\Common Files\VST3\ (Windows) and rescan.

---

Project structure

SpectralMorpher/
├── .github/
│   ├── workflows/build.yml          ← CI: macOS arm64, Windows, Linux
│   └── ISSUE_TEMPLATE/              ← Bug report & feature request forms
├── Source/
│   ├── PluginProcessor.h/cpp        ← AudioProcessor + APVTS parameters
│   ├── PluginEditor.h/cpp           ← UI: LookAndFeel + spectrum analyser
│   └── SpectralEngine.h/cpp         ← Core DSP: FFT, spectral ops, phase vocoder
├── CMakeLists.txt
├── CHANGELOG.md
├── CONTRIBUTING.md
└── LICENSE                          ← MIT

---

Contributing

Contributions are welcome — see CONTRIBUTING.md for setup instructions, code style, and the PR checklist.

---

Technical notes

• FFT size: 2048 samples — balances frequency resolution and latency
• Hop size: 512 samples (75% overlap) — standard for phase vocoder quality
• Window: Hann — optimal sidelobe suppression for spectral processing
• Phase vocoder: Full unwrapped-phase accumulation for artefact-free reconstruction
• Thread safety: All parameters use std::atomic; UI spectrum copy protected by CriticalSection
• No allocations in processBlock() — all buffers pre-allocated in prepareToPlay()

---

License

MIT © 2026 SpectralMorpher Contributors

JUCE is used under the JUCE License. A commercial JUCE license is required if you distribute this plugin commercially.