@audio/reverb-shimmer

Shimmer reverb — octave-up pitch-shifted feedback tail (Valhalla/Eno-Lanois class)

npm install @audio/reverb-shimmer

import shimmer from '@audio/reverb-shimmer'

A 4-comb reverb core whose feedback path is pitch-shifted up an octave before re-injection, so the tail climbs into sparkling upper octaves the longer it rings (Valhalla Shimmer / Eno-Lanois class). The in-loop shifter is a self-contained 2-head varispeed ring buffer (write head advances ×1, two read heads advance ×2 with a triangular crossfade) — no dependency on @audio/shift-*; those packages are for offline high-quality shifting, this one is built to run inside a feedback loop. Mono only.

shimmer(data, { decay: 0.7, shimmer: 0.5, damping: 0.3, mix: 0.4, fs: 44100 })
shimmer(data, { shimmer: 0.9 })  // heavier octave-up content in the tail

| Param | Default | | |---|---|---| | decay | 0.7 | 0..1 — comb feedback (tail length) | | shimmer | 0.5 | 0..1 — amount of octave-up signal re-injected into the feedback path | | damping | 0.3 | 0..1 — high-frequency loss in the comb feedback path | | mix | 0.4 | 0..1 — wet/dry blend | | fs | 44100 | sample rate; delay/ring-buffer lengths scale to it |

Mutates data in place and returns it. Fresh comb and ring-buffer state is allocated per call — no state carries across calls, reprocess the whole buffer each time.

Use when: ambient pads, ethereal tails that climb in pitch as they decay. Not for: natural room/plate character (the octave-up feedback is the deliberate coloration) or stereo width (mono only — run twice with decorrelated seeds for pseudo-stereo).

Part of the @audio/reverb family.

MIT © audiojs