lookas 1.2.0

A high-performance, terminal-based audio spectrum visualizer written in Rust.

Overview

What It Does

Lookas captures microphone input, system audio, or both, converts the signal into frequency bands using a mel-scale FFT, and renders it as smooth, physics-driven bars directly in the terminal.

Adaptive gain control and noise gating keep the display clean. A spring-damper animation model gives the bars weight and continuity instead of raw jitter. Rendering is optimized for terminal throughput and stable frame pacing rather than flashy redraw tricks.

The result is a visualizer that feels connected to the sound, not a noisy oscilloscope clone.

Installation

cargo install lookas

System Audio (Linux)

For system audio capture, Lookas relies on PulseAudio / PipeWire utilities.

If not installed already, run:

sudo apt install pulseaudio-utils

This works on both PulseAudio and PipeWire setups via pipewire-pulse.

Basic Usage

Run with defaults:

lookas

By default, Lookas will attempt to start with system audio. If that fails, it falls back to microphone input.

Controls

1 – Microphone input
2 – System audio (loopback / monitor)
3 – Microphone + system mix
r – Restart audio pipeline
q – Quit

Configuration

Lookas is configured entirely through environment variables.

Frequency & Resolution

Variable	Description	Default	Range
`LOOKAS_FMIN`	Minimum frequency (Hz)	30.0	10.0 – 1000.0
`LOOKAS_FMAX`	Maximum frequency (Hz)	16000.0	1000.0 – 24000.0
`LOOKAS_FFT_SIZE`	FFT window size (power of two)	2048	512 – 4096

Performance & Layout

Variable	Description	Default	Range
`LOOKAS_TARGET_FPS_MS`	Target frame time (ms)	16	8 – 50
`LOOKAS_MODE`	Horizontal layout mode	"rows"	"rows", "columns"

Audio Processing

Variable	Description	Default	Range
`LOOKAS_TAU_SPEC`	Spectrum smoothing constant	0.06	0.01 – 0.20
`LOOKAS_GATE_DB`	Noise gate threshold (dB)	-55.0	-80.0 – -30.0
`LOOKAS_TILT_ALPHA`	Frequency response tilt	0.30	0.0 – 1.0

Animation Physics

Variable	Description	Default	Range
`LOOKAS_FLOW_K`	Horizontal energy diffusion	0.18	0.0 – 1.0
`LOOKAS_SPR_K`	Spring stiffness	60.0	10.0 – 200.0
`LOOKAS_SPR_ZETA`	Spring damping	1.0	0.1 – 2.0

Example Configurations

High frequency resolution:

LOOKAS_FFT_SIZE=4096 LOOKAS_FMIN=20 LOOKAS_FMAX=20000 lookas

Lower CPU usage:

LOOKAS_TARGET_FPS_MS=33 LOOKAS_FFT_SIZE=1024 lookas

Bass-focused music:

LOOKAS_FMIN=20 LOOKAS_FMAX=8000 LOOKAS_TILT_ALPHA=0.1 lookas

Smoother classical dynamics:

LOOKAS_FMIN=40 LOOKAS_FMAX=12000 LOOKAS_TAU_SPEC=0.12 lookas

How It Works

Lookas runs a low-latency audio pipeline designed for visual stability first.

Audio is captured from the microphone, system loopback, or both. The signal is windowed with a Hann function to reduce spectral leakage, then transformed via FFT into frequency bins. These bins are remapped onto a mel-scale filterbank so the visualization aligns with human loudness perception rather than linear frequency spacing.

Dynamic range is managed continuously using percentile tracking instead of fixed scaling. A noise gate suppresses background hiss, while frequency tilt prevents low or high bands from dominating the display.

Animation is driven by a spring-damper model rather than raw amplitude changes. Energy diffuses laterally between neighboring bands, producing motion that feels fluid instead of twitchy. All hot-path operations are allocation-free, cache-friendly, and designed to maintain consistent frame pacing.

Rendering uses dense Unicode block characters to achieve smooth gradients without expensive redraws. The terminal is only cleared once per frame, layout is recomputed only when geometry changes, and output is written in large contiguous chunks to avoid flicker.

On modern Linux systems, this yields a stable 60+ FPS experience with audio-to-visual latency low enough to feel immediate.