@audio/eq-dynamic

Dynamic EQ — per-band peaking gain driven by band energy (Pro-Q3/soothe class)

npm install @audio/eq-dynamic

import dynamicEq from '@audio/eq-dynamic'

The generalized de-esser: each band watches its own energy through a bandpass sidechain and attack/release envelope follower, and only engages a peaking cut (or, in 'up' mode, a boost) once that band crosses threshold — quiet bands stay untouched, loud transients get pulled down proportionally to ratio, capped at maxGain. Peaking coefficients are re-derived every 64-sample block for smooth gain changes without per-sample coefficient cost.

dynamicEq(data, { fs: 44100, bands: [
  { fc: 6000, threshold: -30, ratio: 4, attack: 3, release: 60 },  // de-ess
  { fc: 250, threshold: -20, mode: 'up', maxGain: 6 },             // upward warmth
]})

| Param | Default | | |---|---|---| | bands | [] | Array of per-band settings | | bands[].fc | — | Band center frequency, Hz — both sidechain and peaking filter | | bands[].Q | 2 | Sidechain bandpass / peaking filter Q | | bands[].threshold | -30 | Level, dB, above which gain reduction (or boost) engages | | bands[].ratio | 3 | Compression ratio applied to the amount over threshold | | bands[].attack | 5 | Envelope attack, ms | | bands[].release | 80 | Envelope release, ms | | bands[].maxGain | 12 | Maximum gain change, dB — caps cut ('down') or boost ('up') | | bands[].mode | 'down' | 'down' cuts over-threshold energy; 'up' boosts it instead | | fs | 44100 | Sample rate, Hz |

Unlike the biquad-based atoms in this family, params does not persist state across calls — every call allocates fresh sidechain/audio-path biquad state and envelope followers starting at zero. Each call is a self-contained batch pass, not a streaming chunk: call it once with the whole buffer rather than chunk-by-chunk.

Use when: de-essing, resonance taming, mix-bus "automatic EQ" that only reacts when a band gets too loud — anywhere a static EQ would need constant automation.

Part of @audio/eq — the eq family umbrella.

MIT © audiojs