Miroslav Pejic
107 lines
3.0 KiB
JavaScript
107 lines
3.0 KiB
JavaScript
'use strict';
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/**
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* Start audio pitch detection
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* @param {object} stream media stream audio
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*/
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async function startPitchDetection(stream) {
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if (isAudioContextSupported) {
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pitchDetectionStatus = true;
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audioContext = new (window.AudioContext || window.webkitAudioContext)();
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mediaStreamSource = audioContext.createMediaStreamSource(stream);
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meter = createAudioMeter(audioContext);
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mediaStreamSource.connect(meter);
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}
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}
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/**
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* Check if audio context is supported
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* @returns boolean
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*/
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function isAudioContextSupported() {
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window.AudioContext = window.AudioContext || window.webkitAudioContext;
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if (window.AudioContext) {
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return true;
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}
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return false;
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}
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/**
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* Create audio mixer
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* @param {object} audioContext audio context
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* @param {decimal} clipLevel optional
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* @param {decimal} averaging optional
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* @param {integer} clipLag optional
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* @returns
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*/
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function createAudioMeter(audioContext, clipLevel, averaging, clipLag) {
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const processor = audioContext.createScriptProcessor(512);
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processor.onaudioprocess = volumeAudioProcess;
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processor.clipping = false;
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processor.lastClip = 0;
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processor.volume = 0;
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processor.clipLevel = clipLevel || 0.98;
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processor.averaging = averaging || 0.95;
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processor.clipLag = clipLag || 750;
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// this will have no effect, since we don't copy the input to the output,
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// but works around a current Chrome bug.
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processor.connect(audioContext.destination);
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processor.checkClipping = function () {
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if (!this.clipping) {
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return false;
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}
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if (this.lastClip + this.clipLag < window.performance.now()) {
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this.clipping = false;
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}
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return this.clipping;
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};
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processor.shutdown = function () {
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this.disconnect();
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this.onaudioprocess = null;
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};
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return processor;
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}
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/**
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* Volume audio process
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* @param {object} event audio volume event
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*/
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function volumeAudioProcess(event) {
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const buf = event.inputBuffer.getChannelData(0);
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const bufLength = buf.length;
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let sum = 0;
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let x;
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// Do a root-mean-square on the samples: sum up the squares...
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for (let i = 0; i < bufLength; i++) {
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x = buf[i];
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if (Math.abs(x) >= this.clipLevel) {
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this.clipping = true;
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this.lastClip = window.performance.now();
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}
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sum += x * x;
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}
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// ... then take the square root of the sum.
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const rms = Math.sqrt(sum / bufLength);
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// Now smooth this out with the averaging factor applied
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// to the previous sample - take the max here because we
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// want "fast attack, slow release."
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this.volume = Math.max(rms, this.volume * this.averaging);
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let final_volume = Math.round(this.volume * 100);
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if (myAudioStatus && final_volume > 5) {
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let config = {
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type: 'micVolume',
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peer_id: myPeerId,
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volume: final_volume,
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};
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handleMyVolume(config);
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sendToDataChannel(config);
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}
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}
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