BiquadFilterNode
package js.html.audio
extends AudioNode › EventTarget
Available on js
The BiquadFilterNode interface represents a simple low-order filter, and is created using the AudioContext.createBiquadFilter() method. It is an AudioNode that can represent different kinds of filters, tone control devices, and graphic equalizers.
Documentation BiquadFilterNode by Mozilla Contributors, licensed under CC-BY-SA 2.5.
See also:
Constructor
Throws:
Variables
Is an a-rate AudioParam, a double representing a Q factor, or quality factor.
Is an a-rate AudioParam representing detuning of the frequency in cents.
Is an a-rate AudioParam, a double representing a frequency in the current filtering algorithm measured in hertz (Hz).
Is an a-rate AudioParam, a double representing the gain used in the current filtering algorithm.
Is a string value defining the kind of filtering algorithm the node is implementing.
The meaning of the different parameters depending of the type of the filter (detune has the same meaning regardless, so isn't listed below)
<tr>
<code>type</code>
Description
<code>frequency</code>
<code>Q</code>
<code>gain</code>
</tr>
<tr>
<code>lowpass</code>
<td>Standard second-order resonant lowpass filter with 12dB/octave rolloff. Frequencies below the cutoff pass through; frequencies above it are attenuated.</td>
<td>The cutoff frequency.</td>
<td>Indicates how peaked the frequency is around the cutoff. The greater the value is, the greater is the peak.</td>
<td>Not used</td>
</tr>
<tr>
<code>highpass</code>
<td>Standard second-order resonant highpass filter with 12dB/octave rolloff. Frequencies below the cutoff are attenuated; frequencies above it pass through.</td>
<td>The cutoff frequency.</td>
<td>Indicates how peaked the frequency is around the cutoff. The greater the value, the greater the peak.</td>
<td>Not used</td>
</tr>
<tr>
<code>bandpass</code>
<td>Standard second-order bandpass filter. Frequencies outside the given range of frequencies are attenuated; the frequencies inside it pass through.</td>
<td>The center of the range of frequencies.</td>
<td>Controls the width of the frequency band. The greater the <code>Q</code> value, the smaller the frequency band.</td>
<td>Not used</td>
</tr>
<tr>
<code>lowshelf</code>
<td>Standard second-order lowshelf filter. Frequencies lower than the frequency get a boost, or an attenuation; frequencies over it are unchanged.</td>
<td>The upper limit of the frequencies getting a boost or an attenuation.</td>
<td>Not used</td>
<td>The boost, in dB, to be applied; if negative, it will be an attenuation.</td>
</tr>
<tr>
<code>highshelf</code>
<td>Standard second-order highshelf filter. Frequencies higher than the frequency get a boost or an attenuation; frequencies lower than it are unchanged.</td>
<td>The lower limit of the frequencies getting a boost or an attenuation.</td>
<td>Not used</td>
<td>The boost, in dB, to be applied; if negative, it will be an attenuation.</td>
</tr>
<tr>
<code>peaking</code>
<td>Frequencies inside the range get a boost or an attenuation; frequencies outside it are unchanged.</td>
<td>The middle of the frequency range getting a boost or an attenuation.</td>
<td>Controls the width of the frequency band. The greater the <code>Q</code> value, the smaller the frequency band.</td>
<td>The boost, in dB, to be applied; if negative, it will be an attenuation.</td>
</tr>
<tr>
<code>notch</code>
<td>Standard notch filter, also called a band-stop or band-rejection filter. It is the opposite of a bandpass filter: frequencies outside the give range of frequencies pass through; frequencies inside it are attenuated.</td>
<td>The center of the range of frequencies.</td>
<td>Controls the width of the frequency band. The greater the <code>Q</code> value, the smaller the frequency band.</td>
<td>Not used</td>
</tr>
<tr>
<code>allpass</code>
<td>Standard second-order allpass filter. It lets all frequencies through, but changes the phase-relationship between the various frequencies.</td>
<td>The frequency with the maximal group delay, that is, the frequency where the center of the phase transition occurs.</td>
<td>Controls how sharp the transition is at the medium frequency. The larger this parameter is, the sharper and larger the transition will be.</td>
<td>Not used</td>
</tr>
Methods
From the current filter parameter settings this method calculates the frequency response for frequencies specified in the provided array of frequencies.