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