Class StereoPanner

Positions a signal in the stereo field and controls its stereo width. Built from native Web Audio nodes, so it does not require WebAssembly.

Extends Effector.

Signal flow

input (forced to stereo) -> splitter -> width matrix -> merger -> StereoPannerNode -> output

The width matrix is a mid/side operation that scales the side signal (L - R) by width:

out L = L * (1 + width) / 2 + R * (1 - width) / 2
out R = L * (1 - width) / 2 + R * (1 + width) / 2

| width | Result | |---|---| | 0 | Mono: both channels carry (L + R) / 2 | | 1 | Unchanged | | 2 | Extra wide: the side signal is doubled |

A mono input is upmixed to both channels first, so width has no effect on it, but pan does.

Example

import { StereoPanner } from "@fluex/fluexgl-dsp";

const panner = new StereoPanner({ pan: -0.3, width: 1.4 });

channel.addEffect(panner);

panner.setWidth(0); // collapse to mono

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Constructor

new StereoPanner(options?: Partial<StereoPannerOptions>): StereoPanner;

Arguments

• options?: Partial<StereoPannerOptions>

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Properties

pan: number

Position, between -1 (left) and 1 (right). Defaults to 0.

width: number

Stereo width, between 0 (mono) and 2 (extra wide). Defaults to 1.

inputGainNode: GainNode | null

Input node, forced to 2 channels (channelCountMode: "explicit"). null until attached.

pannerNode: StereoPannerNode | null

Output node. null until attached.

label and name default to "StereoPanner".

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Methods

initializeOnAttachment(context: AudioContext): Promise<void>

Creates the native nodes.

returnOptionsAsObject(): StereoPannerOptions

Returns { pan, width }.

setPan(pan: number): boolean

Sets the position, clamped between -1 and 1, with a 10 ms ramp.

Arguments

• pan: number

Returns

• boolean - true when applied to the audio node, false when the effect is not attached yet (the value is used on attachment).

setWidth(width: number): boolean

Sets the stereo width, clamped between 0 and 2, with a 10 ms ramp.

Arguments

• width: number

Returns

• boolean - true when applied to the audio nodes, false when the effect is not attached yet.

Getters and setters

get inputNode(): AudioNode | null

Returns inputGainNode.

get outputNode(): AudioNode | null

Returns pannerNode.

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Events

StereoPanner does not use an AudioWorklet processor, so it does not dispatch processor events.

Notes

Every Channel can already pan with channel.pan(), which creates a StereoPannerNode after the effects on first use. Use this effect when you also need width control, or panning at a specific position in an effect chain.