Plugin: Equalizer

EqualizerPlugin (id 'equalizer') is a 10-band parametric equalizer plus a pre-gain stage, built from BiquadFilterNodes inserted into Audio Graph’s chain.

Options

Option	Type	Default	Purpose
`bands`	`EqBand[]`	`DEFAULT_BANDS`	10 frequency bands. Element 0 must be the `{ frequency: 'Pre', gain }` pseudo-band.
`preset`	`string`	—	Preset name to apply on `use()`.
`presets`	`EqPreset[]`	—	Additional presets beyond the built-ins.
`sliderValues`	`EqSliderValues`	`DEFAULT_SLIDER_VALUES`	Min/max/step/default per slider, for a UI to read directly.
`persistKey`	`string`	—	Storage key. Omit to disable persistence.
`autoLoad` / `autoSave`	`boolean`	`true` / `true` when `persistKey` set	Load/save automatically through `this.storage`.
`smoothingTimeConstantSeconds`	`number`	`0.05`	Ramp time for gain changes, avoids audible clicks.

EqBand is { frequency: number | 'Pre'; gain: number; q?: number; type?: BiquadFilterType }.

Events

ready, band:changed ({ band }), preset:changed ({ name }), change ({ bands, selectedPreset }), saved.

Rules & restrictions

static requires = [AudioGraphPlugin] — register Audio Graph first, the equalizer throws core:plugin/missing-dep otherwise.
bands[0] is a fixed contract: it must be the 'Pre' pseudo-band, not a real frequency.
Persistence goes through this.storage, the plugin’s own scoped, namespaced storage, never raw localStorage. Swapping the storage adapter moves equalizer persistence with it, same as everything else that uses this.storage.
Pre-gain has a sticky-zero snap: values within ±0.05 of zero round to exactly zero, so a UI slider settles cleanly at the middle instead of hovering at 0.0003.

How to extend it

TypeScript

import nmplayer from '@nomercy-entertainment/nomercy-video-player'; // nomercy-music-player's factory works identically
import { AudioGraphPlugin, EqualizerPlugin } from '@nomercy-entertainment/nomercy-player-core';

const player = nmplayer('player');

player.addPlugin(AudioGraphPlugin);
player.addPlugin(EqualizerPlugin, { persistKey: 'my-app-eq' });
await player.ready();

const eq = player.getPlugin(EqualizerPlugin);
eq!.band(1000, 4); // +4 dB at 1 kHz
eq!.preset('Rock');
eq!.save();

Next steps

Plugin: Mixer: the master gain and pan stage at the tail of the same chain.