Strudel patterns must include .analyze('hydra') for visuals to receive FFT data — an untagged pattern plays audio but the visuals see a.fft = 0

The Strudel→Hydra bridge in this rig works by reading an audio analysis tag set on the pattern. Only patterns that include .analyze(‘hydra’) contribute audio analysis data to the shared a.fft[] array that Hydra and GLSL visuals read. An untagged pattern plays audio normally but the bridge sees zero signal — visuals driven by a.fft will not react. The rig provides only 4 FFT bins (a.fft[0] through a.fft[3]); a.fft[4] is undefined. No other audio analysis features (onset, tempo, RMS, spectral centroid, per-instrument signal) are available at this rig level.

Examples

$: s("bd*4").analyze('hydra') — visuals receive kick transients in a.fft. $: s("bd*4") — audio plays but a.fft stays 0.

Assessment

A performer hears audio but their Hydra visuals do not react. List the two most likely causes (one naming, one bridging) and give the fix for each.