phosphor-audio

‍Audio spectrum input for audio-reactive shaders and overlays.

Responsibility

A lightweight audio-spectrum feed for shader effects and QML overlays. One contract (IAudioSpectrumProvider) and one bundled implementation that shells out to the user's cava install; consumers wire the emitted bar vector into a ShaderEffect UBO.

Key types

Type	Purpose
PhosphorAudio::IAudioSpectrumProvider	Provider contract: start, stop, bar count, framerate, spectrum() snapshot.
PhosphorAudio::CavaSpectrumProvider	cava-backed provider. Detects install, picks an audio method (PulseAudio / PipeWire / ALSA), builds a throwaway config, emits normalized FFT bars.

Typical use

auto* provider = new PhosphorAudio::CavaSpectrumProvider(parent);
provider->setBarCount(64);
provider->setFramerate(60);
QObject::connect(provider, &IAudioSpectrumProvider::spectrumUpdated,
                 shaderEffect, &MyShader::setBars);
provider->start();

Design notes

• No direct audio backend. CavaSpectrumProvider shells out to cava, which handles PulseAudio / PipeWire / ALSA detection and owns the FFT. The lib parses its framed byte output.
• Graceful degradation. isAvailable() returns false when cava is not installed; consumers should hide or disable audio-reactive overlays in that case rather than hard-fail.

Dependencies

• QtCore

See also

• `phosphor-shaders` — spectrum feeds shader UBOs through IUniformExtension.
• `phosphor-rendering` — host item that consumes the spectrum.