A VU meter on the whole grid: every light pulses with the microphone's sound level, its colour ramping from calm green (quiet) toward hot red (loud). The simplest audio-reactive effect: one scalar drives one brightness.
Reads the live frame from AudioModule::latestFrame(); with no microphone (or in silence) the level is zero and the grid stays dark, so the effect is safe on any target and grid size.
- brightness: overall ceiling (1-255). Default 255.
The colour is a level-driven green→red ramp; modifiers and layouts give the flat VU surface its shape. Like every effect it writes only logical RGB; the driver's Correction applies channel order and, for an RGBW preset, derives the white channel (W = min(R, G, B)) after brightness scaling.