BiquadFilterNode

The BiquadFilterNode interface of the Web Audio API represents a second-order recursive linear filter, also known as a biquad filter. It is used to implement a variety of common signal processing filters, including lowpass, highpass, bandpass, low-shelf, high-shelf, peaking, notch, and allpass filters. The BiquadFilterNode interface inherits properties and methods from its parent, AudioNode.

A BiquadFilterNode always has exactly one input and one output. The number of channels in the input and output must match. If the input has more channels than the output, the additional channels are ignored. If the input has fewer channels than the output, the missing channels are set to zero.

The BiquadFilterNode interface provides a set of properties that allow the filter's parameters to be controlled. These include the filter type, the cutoff frequency, the Q factor, the gain, and the detune amount. The filter type can be set to one of the following values: lowpass, highpass, bandpass, lowshelf, highshelf, peaking, notch, or allpass.

The BiquadFilterNode interface also provides a method called getFrequencyResponse, which can be used to obtain the frequency response of the filter. This method takes three arguments: an array of frequencies, an array to store the magnitude response, and an array to store the phase response. The magnitude and phase responses are calculated for each frequency in the input array and stored in the corresponding output arrays.

In summary, the BiquadFilterNode interface is a powerful tool for implementing a wide range of audio effects in web applications. Its ability to control filter parameters and obtain frequency response data makes it a valuable component of the Web Audio API.