@audio/effect-sbr

Spectral band replication — extend HF from midband harmonics (aural exciter family; De-Slop bandwidth recovery)

Exciter-class bandwidth recovery: takes the top octave still present below cutoff, regenerates its harmonic series with a waveshaper (harmonics land above cutoff), highpasses at cutoff, and mixes back in at a level tracking the source band's envelope. Recovers HF lost to lossy encoding or a lowpassed source.

Install

npm install @audio/effect-sbr

Usage

import sbr from '@audio/effect-sbr'

let p = { cutoff: 8000, amount: 0.5, drive: 0.5, fs: 44100 }
for (let buf of stream) sbr(buf, p)

sbr(data, params) mutates data (Float32Array/Float64Array) in place and returns it. Pass the same params object across calls — the source bandpass, output highpass, and envelope-follower state persist on it (_src, _hp1, _hp2, _env, _henv, _dc).

cutoff where the source content dies, Hz (default 8000) · amount replication level 0–1 (default 0.5) · drive waveshaper intensity 0–1 (default 0.5) · fs sample rate

Use when: restoring HF on lossy-encoded or bandwidth-limited material, mastering "air" Not for: adding harmonics to a full-bandwidth source (use @audio/effect-exciter) or bass reconstruction (use @audio/effect-subbass)

Part of @audio/effect.