a.bins gives Hydra's un-normalised FFT values and a.prevBins gives the previous frame's, enabling delta-based reactivity

Alongside the 0–1-mapped a.fft array, Hydra exposes the raw per-bin amplitudes via a.bins, without the scaling/cutoff mapping to 0–1. It also keeps the previous frame’s values in a.prevBins. Raw values are useful when you need absolute magnitudes rather than a calibrated 0–1 signal, and comparing a.bins against a.prevBins lets you compute a per-bin change (a delta) between frames — the basis for reacting to onsets or rate-of-change rather than to absolute level. Because a.prevBins is exactly one frame behind, a large positive a.bins[i] - a.prevBins[i] signals a rising transient in that band.

Examples

a.setBins(4)
// flash on a rising low-band transient
osc(30,0.1)
  .luma(()=> (a.bins[0]-a.prevBins[0])>0.1 ? 0 : 0.5)
  .out()

Assessment

Explain the difference between a.fft[0] and a.bins[0], and write an expression using a.bins and a.prevBins that is large only when the low band is rising.