C FFT Visualizer

Visualize the Fast Fourier Transform (FFT) of audio signals in real-time using C, FFTW3, Raylib and PortAudio. Includes RTA-style smoothing, per-band peak-hold, and pink-noise compensation.

Warning

Early prototype. Only supports .wav audio files for now or Live microphone. Sample rates of 48kHz and higher may make the visualization lag relative to the audio.

Requirements

• C Compiler
• Raylib
• FFTW3

Arch Linux:

sudo pacman -S clang raylib fftw portaudio

Build and run

chmod +x build.sh
./build.sh

# Audio file
./build/c_fft_visualizer <path_to_audio_file> <--loop (optional)>

# Live microphone
./build/c_fft_visualizer --mic

Features

• Log-frequency bars with fractional-octave smoothing (1/1…1/48)
• dB-domain time averaging (EMA) with Fast/Slow presets
• Frequency weighting modes (Z/A/C)
• SPL calibration workflow (94 dB calibrator via key command)
• Per-band peak-hold with timed decay
• Persistent max-hold trace (manual clear)
• Peak-find + nearest-band lock navigation
• Pink compensation (pink-flat display)
• dB grid overlay and peak/RMS meters
• Cursor readout (hover for exact Hz and level)
• Use a live microphone with the flag: --mic

Controls

• O: Change octave scaling (1/1…1/48)
• C: Cycle color gradients
• P: Toggle pink compensation
• A: Toggle dB-domain averaging (v.s. linear)
• F: Toggle Fast/Slow averaging preset
• H: Cycle peak-hold (Off, 0.5s, 1.0s, 2.0s)
• W: Cycle frequency weighting (Z/A/C)
• T: Cycle meter time weighting (Fast/Slow/Impulse)
• K: Calibrate SPL to 94 dB reference (mic mode only)
• G: Peak-find from max-hold trace and lock cursor
• Left/Right: Step locked band by one bar
• Mouse Left: Toggle nearest-band lock
• R: Reset peak and max-hold traces
• Space: Freeze/Unfreeze live trace
• F11: Toggle fullscreen

Configuration

Edit include/config.h to tune defaults

• Default FFT settings are FFT_WINDOW_SIZE=8192, FFT_HOP_SIZE=FFT_WINDOW_SIZE/16 for a professional RTA-style balance of low-end detail and low display latency.
• Increase FFT_WINDOW_SIZE if you want even finer bass resolution, or decrease it for the fastest transient tracking.
• Increase or decrease UI_SCALE to resize on-screen text/panels globally if the UI looks too small or too large on your display.

Screenshot

License

GPL-3.0 License