A visual pulse is amplitude-following, not beat-locked, and will drift from the musical grid

Driving a visual-pulse or strobe-flash from a bass FFT bin (a.fft[0]) makes the image swell when the bass is loud, which tends to correlate with kick hits — but this is amplitude-following, not beat-detection. The pulse will smear across the grid and drift over a set; it is not quantized to the downbeat. The correct mental model is ‘reacts to loudness’, not ‘fires on the beat’. To improve the correspondence, tune the shim’s smoothing (a.setSmooth) to control how fast the envelope rises and falls.

Examples

osc(10,0.1,()=>0.6+a.fft[0]*2.5) — brightness swells with bass energy and reads as roughly on-beat during a four-on-the-floor passage, but an envelope-based assessment would show the swell lags the actual kick by one or more display frames.

Assessment

Record a 16-bar loop with a 4/4 kick. Describe whether a bass-driven visual-pulse lands exactly on each beat, and explain why or why not using the update-cadence and smoothing mechanism.