three
Version:
JavaScript 3D library
98 lines (79 loc) • 2.33 kB
JavaScript
/**
* This class can be used to analyse audio data.
*
* ```js
* // create an AudioListener and add it to the camera
* const listener = new THREE.AudioListener();
* camera.add( listener );
*
* // create an Audio source
* const sound = new THREE.Audio( listener );
*
* // load a sound and set it as the Audio object's buffer
* const audioLoader = new THREE.AudioLoader();
* audioLoader.load( 'sounds/ambient.ogg', function( buffer ) {
* sound.setBuffer( buffer );
* sound.setLoop(true);
* sound.setVolume(0.5);
* sound.play();
* });
*
* // create an AudioAnalyser, passing in the sound and desired fftSize
* const analyser = new THREE.AudioAnalyser( sound, 32 );
*
* // get the average frequency of the sound
* const data = analyser.getAverageFrequency();
* ```
*/
class AudioAnalyser {
/**
* Constructs a new audio analyzer.
*
* @param {Audio} audio - The audio to analyze.
* @param {number} [fftSize=2048] - The window size in samples that is used when performing a Fast Fourier Transform (FFT) to get frequency domain data.
*/
constructor( audio, fftSize = 2048 ) {
/**
* The global audio listener.
*
* @type {AnalyserNode}
*/
this.analyser = audio.context.createAnalyser();
this.analyser.fftSize = fftSize;
/**
* Holds the analyzed data.
*
* @type {Uint8Array}
*/
this.data = new Uint8Array( this.analyser.frequencyBinCount );
audio.getOutput().connect( this.analyser );
}
/**
* Returns an array with frequency data of the audio.
*
* Each item in the array represents the decibel value for a specific frequency.
* The frequencies are spread linearly from 0 to 1/2 of the sample rate.
* For example, for 48000 sample rate, the last item of the array will represent
* the decibel value for 24000 Hz.
*
* @return {Uint8Array} The frequency data.
*/
getFrequencyData() {
this.analyser.getByteFrequencyData( this.data );
return this.data;
}
/**
* Returns the average of the frequencies returned by {@link AudioAnalyser#getFrequencyData}.
*
* @return {number} The average frequency.
*/
getAverageFrequency() {
let value = 0;
const data = this.getFrequencyData();
for ( let i = 0; i < data.length; i ++ ) {
value += data[ i ];
}
return value / data.length;
}
}
export { AudioAnalyser };