cava_plus_plus

A small terminal audio spectrum visualizer in Rust. It is like cava.

NOTE: This is a toy project. It is not finished. Many features are missing. Use it for fun and learning only.

Demo

mini_cava can show 4 display modes. The 4 videos below show each mode.

You can only change the mode by editing the const values in src/main.rs and rebuilding. There is no runtime switch yet.

Mode 1

Mode 2

Mode 3

Mode 4

Environment

This project was only tested on:

• Arch Linux
• PipeWire (only, no PulseAudio or JACK)

It reads audio from the PipeWire default_sink monitor. It may not work on other systems.

Dependencies

• Rust (nightly, edition 2024)
• System libraries: pkgconf, pipewire, alsa-lib, clang

Install on Arch Linux:

./install_deps.sh

Build and run

cargo run

Press q to quit.

How it works

• cpal (PipeWire host) captures the default_sink monitor.
• Samples go through a ring buffer, then rustfft does an FFT.
• FFT size is 1024, with a Hanning window. Stereo is mixed to mono.
• DC is removed by subtracting each frame's mean before windowing.
• Each bar sums the linear magnitudes (norm / window_sum) of its FFT bins, then converts to dB with 20 * log10(sum).
• crossterm draws the bars on the alternate screen.
• Bars use a log-frequency scale from 40 Hz to 13 kHz.
• A cava-style noise-reduction filter smooths each bar over time: a falloff curve for the falling edge plus an integral low-pass.
• autosens uses cava's multiplicative gain (overshoot detection) to keep the tallest bar near the top without amplifying the noise floor during silence.
• Optional monstercat / waves filters blend neighbouring bars.
• A damped-oscillator spring animates each bar toward its target, overshooting and bouncing back (non-linear rebound) instead of moving monotonically.
• Each bar has a peak cap that falls slowly.
• Bar color is an HSV rainbow gradient: hue sweeps continuously from GRADIENT_START_HUE (bottom) to GRADIENT_END_HUE (top).
• The gradient's palette continuously cycles over time: a running hue phase rotates both GRADIENT_START_HUE and GRADIENT_END_HUE together, and the cycling speed is set by the smoothed audio intensity (INTENSITY_SMOOTHING), from a slow idle rate (HUE_CYCLE_BASE_SPEED) up to a fast rate at full intensity (HUE_CYCLE_INTENSITY_SPEED).
• Full cells use the half-block ▀ with the top half in the foreground colour and the bottom half in the background colour, giving half-cell gradient steps.

Tuning

Change these const values in src/main.rs:

Constant	Default	Meaning
FFT_SIZE	1024	FFT window size
DB_FLOOR	-60.0	dB floor for bar height
GRAVITY	1.5	power curve (>1 drops quiet bars)
NOISE_REDUCTION	0.77	noise-reduction strength (0..1]
FRAMERATE	60.0	nominal frame rate for smoothing/autosens
AUTOSENS	1.0	autosens gain rise speed
MONSTERCAT	0.0	monstercat neighbour smoothing (0 = off)
WAVES	0	waves neighbour smoothing (0 = off)
SPRING_STIFFNESS	0.16	spring stiffness (higher = harder/faster)
SPRING_DAMPING	0.70	spring damping (lower = more bounce)
BAR_AMPLITUDE	1.2	bar height multiplier (>1 = taller)
INTENSITY_SMOOTHING	0.08	intensity envelope smoothing (lower=slower)
HUE_CYCLE_BASE_SPEED	0.3	idle palette spin speed (deg/frame)
HUE_CYCLE_INTENSITY_SPEED	3.0	extra spin speed at full intensity (deg/frame)
LOWER_CUTOFF_FREQ	40.0	lowest bar frequency (Hz)
HIGHER_CUTOFF_FREQ	13000.0	highest bar frequency (Hz)
CAP_SIZE	0	peak cap height (1/8 cells, 8 = 1 cell)
CAP_GRAVITY	1.0	peak cap fall step (1/8 cells)
BAR_WIDTH	3	bar width (columns)
BAR_SPACING	1	gap between bars (columns)
GRADIENT_START_HUE	0.0	gradient hue at the bottom (deg)
GRADIENT_END_HUE	240.0	gradient hue at the top (deg)
GRADIENT_SAT	1.0	gradient saturation (0..1)
GRADIENT_VAL	1.0	gradient value/brightness (0..1)