API Reference

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API Reference / getBiquadFilter

Function: getBiquadFilter()

function getBiquadFilter(context, options?): BiquadFilterNode;

Defined in: core/analyzer.ts:143

Creates a biquad lowpass filter for audio processing.

This filter helps isolate low-frequency components (bass) from the audio signal, which is useful for detecting rhythmic patterns and beats in BPM analysis.

Parameters

Parameter	Type	Description
context	OfflineAudioContext | AudioContext	The AudioContext or OfflineAudioContext to create the filter in
options?	BiquadFilterOptions	Optional configuration for the filter's frequency and quality

Returns

BiquadFilterNode

A configured BiquadFilterNode ready to use in an audio graph

Example

const audioContext = new AudioContext();
const filter = getBiquadFilter(audioContext, {
  frequencyValue: 150,  // Hz - frequencies above this are attenuated
  qualityValue: 1       // Q factor - steepness of the filter
});

// Use in an audio graph
source.connect(filter);
filter.connect(audioContext.destination);

Remarks

• Default frequency is optimized for detecting bass drum kicks
• The lowpass filter attenuates high frequencies while preserving low frequencies
• Higher Q values create a steeper filter curve

See

• analyzeFullBuffer which uses this filter internally
• BiquadFilterOptions for configuration options