FFT Freezer

JUCE audio plugin that captures live audio and creates perfect seamless loops via spectral freezing (FFT magnitude preservation with phase randomization).

Ported from vb.freezer~ by Volker Boehm (Max/MSP external) to a standalone JUCE VST3/Standalone plugin.

How it works

1. Audio is continuously recorded into a ring buffer
2. Press SAMPLE — the buffer is windowed, FFT'd, magnitudes are extracted, phases are randomized, then IFFT'd back to time domain
3. The result is a perfect seamless loop — because the magnitude spectrum is preserved but phase information is destroyed, the waveform tiles seamlessly at the FFT boundary
4. Press WRITE TO DISK — saves the frozen loop as a 24-bit WAV file

Controls

Control	Description
SAMPLE	Freeze the current audio input
WRITE TO DISK	Save the frozen loop as WAV
Threshold	Spectral gate — bins below this magnitude are zeroed
Mix	Dry/wet blend (0 = passthrough, 1 = fully frozen)
Rec Length	Recording buffer duration (0.1s – 10s)

Building

Requires CMake 3.22+ and a C++17 compiler. JUCE is fetched automatically.

mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
cmake --build . --config Release -j$(nproc)

Outputs:

• Standalone: build/FFTFreezer_artefacts/Release/Standalone/FFT Freezer
• VST3: build/FFTFreezer_artefacts/Release/VST3/FFT Freezer.vst3/

The VST3 is also auto-installed to ~/.vst3/ on Linux.

Credits

• Original algorithm by Volker Boehm (vb.freezer~, 2011–2020)
• JUCE port uses juce::dsp::FFT — no external FFTW dependency needed

License

MIT