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The type
property of the BiquadFilterNode
interface is a string (enum) value defining the kind of filtering algorithm the node is implementing.
Syntax
var audioCtx = new AudioContext(); var biquadFilter = audioCtx.createBiquadFilter(); biquadfilter.type = 'lowpass';
Value
A string (enum) representing a BiquadFilterType.
type
values and their meaning
type |
Description | frequency |
Q |
gain |
---|---|---|---|---|
lowpass |
Standard second-order resonant lowpass filter with 12dB/octave rolloff. Frequencies below the cutoff pass through; frequencies above it are attenuated. | The cutoff frequency. | Indicates how peaked the frequency is around the cutoff. The greater the value is, the greater is the peak. | Not used |
highpass |
Standard second-order resonant highpass filter with 12dB/octave rolloff. Frequencies below the cutoff are attenuated; frequencies above it pass through. | The cutoff frequency. | Indicates how peaked the frequency is around the cutoff. The greater the value, the greater the peak. | Not used |
bandpass |
Standard second-order bandpass filter. Frequencies outside the given range of frequencies are attenuated; the frequencies inside it pass through. | The center of the range of frequencies. | Controls the width of the frequency band. The greater the Q value, the larger the frequency band. |
Not used |
lowshelf |
Standard second-order lowshelf filer. Frequencies lower than the frequency get a boost, or an attenuation; frequencies over it are unchanged. | The upper limit of the frequencies getting a boost or an attenuation. | Not used | The boost, in dB, to be applied; if negative, it will be an attenuation. |
highshelf |
Standard second-order highshelf filer. Frequencies higher than the frequency get a boost or an attenuation; frequencies lower than it are unchanged. | The lower limit of the frequencies getting a boost or an attenuation. | Not used | The boost, in dB, to be applied; if negative, it will be an attenuation. |
peaking |
Frequencies inside the range get a boost or an attenuation; frequencies outside it are unchanged. | The middle of the frequency range getting a boost or an attenuation. | Controls the width of the frequency band. The greater the Q value, the larger the frequency band. |
The boost, in dB, to be applied; if negative, it will be an attenuation. |
notch |
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. | The center of the range of frequencies. | Controls the width of the frequency band. The greater the Q value, the larger the frequency band. |
Not used |
allpass |
Standard second-order allpass filter. It Lets all frequencies through, but changes the phase-relationship between the various frequencies. | The frequency with the maximal group delay, that is, the frequency where the center of the phase transition occurs. | Controls how sharp the transition is at the medium frequency. The larger this parameter is, the sharper and larger the transition will be. | Not used |
Example
The following example shows basic usage of an AudioContext to create a Biquad filter node. For a complete working example, check out our voice-change-o-matic demo (look at the source code too).
var audioCtx = new (window.AudioContext || window.webkitAudioContext)(); //set up the different audio nodes we will use for the app var analyser = audioCtx.createAnalyser(); var distortion = audioCtx.createWaveShaper(); var gainNode = audioCtx.createGain(); var biquadFilter = audioCtx.createBiquadFilter(); var convolver = audioCtx.createConvolver(); // connect the nodes together source = audioCtx.createMediaStreamSource(stream); source.connect(analyser); analyser.connect(distortion); distortion.connect(biquadFilter); biquadFilter.connect(convolver); convolver.connect(gainNode); gainNode.connect(audioCtx.destination); // Manipulate the Biquad filter biquadFilter.type = "lowshelf"; biquadFilter.frequency.value = 1000; biquadFilter.gain.value = 25;
Specifications
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'type' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 10.0webkit | 25.0 (25.0) | Not supported | 15.0webkit 22 (unprefixed) |
6.0webkit |
Feature | Android | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | ? | 26.0 | 1.2 | ? | ? | ? | 33.0 |
See also
Document Tags and Contributors
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Contributors to this page:
fscholz,
chrisdavidmills
Last updated by:
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