IIRFilterNode: IIRFilterNode() constructor

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2021.

The IIRFilterNode() constructor of the Web Audio API creates a new IIRFilterNode object which an AudioNode processor which implements a general infinite impulse response filter.

Syntax

new IIRFilterNode(context, options)

Parameters

context

A reference to an AudioContext.

options

Options are as follows:

feedforward

A sequence of feedforward coefficients.

feedback

A sequence of feedback coefficients.

channelCount

Represents an integer used to determine how many channels are used when up-mixing and down-mixing connections to any inputs to the node. (See AudioNode.channelCount for more information.) Its usage and precise definition depend on the value of channelCountMode.

channelCountMode

Represents an enumerated value describing the way channels must be matched between the node's inputs and outputs. (See AudioNode.channelCountMode for more information including default values.)

channelInterpretation

Represents an enumerated value describing the meaning of the channels. This interpretation will define how audio up-mixing and down-mixing will happen. The possible values are "speakers" or "discrete". (See AudioNode.channelCountMode for more information including default values.)

Unlike other nodes in the Web Audio API, the options passed into the IIR filter upon creation are not optional. The filter needs these values to work and with the vast range of filters available, there is no default.

Return value

A new IIRFilterNode object instance.

Examples

js
let feedForward = [0.00020298, 0.0004059599, 0.00020298];
let feedBackward = [1.0126964558, -1.9991880801, 0.9873035442];

const audioCtx = new AudioContext();

const iirFilter = new IIRFilterNode(audioCtx, {
  feedforward: feedForward,
  feedback: feedBackward,
});