307 lines
9.0 KiB
JavaScript
307 lines
9.0 KiB
JavaScript
var audioContext;
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var sendButton;
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var textToSend;
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var isListeningCheckbox;
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var samplesPerBitLabel;
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var microphoneStream;
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var microphoneNode;
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var analyser;
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var receivedDataTextarea;
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var sentDataTextArea;
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var receivedGraph;
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var receivedData = [];
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var MAX_DATA_POINTS = 1024;
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// 20 to 20,000 - human
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var FREQUENCY_TONE = 18000;
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var FREQUENCY_HIGH = 900;
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var FREQUENCY_LOW = 1200;
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// 190 = 11.63 samples
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// 180 = 11 samples
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var FREQUENCY_DURATION = 170;
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var FREQUENCY_THRESHOLD = 200;
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var frequencyOverTime = [];
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var bitStart = [];
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var samplesPerBit = [];
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var bitSampleCount = 0;
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function handleWindowLoad() {
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// grab dom elements
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sendButton = document.getElementById('send-button');
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isListeningCheckbox = document.getElementById('is-listening-checkbox');
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receivedDataTextarea = document.getElementById('received-data');
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receivedGraph = document.getElementById('received-graph');
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textToSend = document.getElementById('text-to-send');
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sentDataTextArea = document.getElementById('sent-data');
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samplesPerBitLabel = document.getElementById('samples-per-bit');
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document.getElementById('bit-duration-text').addEventListener('input', (event) => {
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FREQUENCY_DURATION = parseInt(event.target.value);
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bitSampleCount = 0;
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samplesPerBit.length = 0;
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})
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// wire up events
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sendButton.addEventListener('click', handleSendButtonClick);
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isListeningCheckbox.addEventListener('click', handleListeningCheckbox);
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textToSend.addEventListener('keypress', handleTextToSendKeypress);
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}
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function handleTextToSendKeypress(event) {
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var keyCode = event.which || event.keyCode;
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var bits = keyCode.toString(2)
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.padStart(8, '0')
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.split('')
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.map(Number);
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sendBits(bits);
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}
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function getFrequency(bit) {
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return bit ? FREQUENCY_HIGH : FREQUENCY_LOW;
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}
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function sendBits(bits) {
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sentDataTextArea.value += bits.join('') + '\n';
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sentDataTextArea.scrollTop = sentDataTextArea.scrollHeight;
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var audioContext = getAudioContext();
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var oscillator = audioContext.createOscillator();
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var duration = bits.length * FREQUENCY_DURATION;
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for(var i = 0; i < bits.length; i++) {
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if(i > 0 && bits[i] === bits[i-1]) continue;
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var offset = ((i * FREQUENCY_DURATION)/1000);
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oscillator.frequency.setValueAtTime(
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getFrequency(bits[i]),
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audioContext.currentTime + offset
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);
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}
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oscillator.connect(audioContext.destination);
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oscillator.start();
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window.setTimeout(function() { oscillator.stop(); }, duration);
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}
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function getAudioContext() {
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if(!audioContext) {
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audioContext = new (window.AudioContext || webkitAudioContext)();
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}
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if(audioContext.state === 'suspended') {
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audioContext.resume();
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}
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return audioContext;
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}
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function handleSendButtonClick() {
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var audioContext = getAudioContext();
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var oscillator = audioContext.createOscillator();
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oscillator.frequency.setValueAtTime(FREQUENCY_TONE, audioContext.currentTime);
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oscillator.connect(audioContext.destination);
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oscillator.start();
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window.setTimeout(function() { oscillator.stop(); }, 500);
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}
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function handleListeningCheckbox(e) {
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var audioContext = getAudioContext();
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function handleMicrophoneOn(stream) {
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microphoneStream = stream;
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microphoneNode = audioContext.createMediaStreamSource(stream);
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analyser = audioContext.createAnalyser();
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analyser.smoothingTimeConstant = 0;
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analyser.fftSize = 2 ** 12;
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microphoneNode.connect(analyser);
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requestAnimationFrame(analyzeAudio);
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}
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function handleMicrophoneError(error) {
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console.error('Microphone Error', error);
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}
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if(e.target.checked) {
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navigator.mediaDevices
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.getUserMedia({
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audio: {
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mandatory: {
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autoGainControl: false,
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echoCancellation: false,
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noiseSuppression: false,
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suppressLocalAudioPlayback: false,
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voiceIsolation: false
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},
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optional: []
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}
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})
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.then(handleMicrophoneOn)
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.catch(handleMicrophoneError)
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} else {
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if(microphoneStream) {
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microphoneStream.getTracks().forEach(track => track.stop());
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microphoneStream = undefined;
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}
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if(analyser && microphoneNode) {
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try {
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analyser.disconnect(microphoneNode);
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} catch(e) {
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}
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microphoneNode = undefined;
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analyser = undefined;
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}
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}
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}
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function received(value) {
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receivedDataTextarea.value += value;
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receivedDataTextarea.scrollTop = receivedDataTextarea.scrollHeight;
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}
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let bitStarted;
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let bitHighStrength = [];
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let bitLowStrength = [];
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function analyzeAudio() {
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if(!analyser) return;
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if(!microphoneNode) return;
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var audioContext = getAudioContext();
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const frequencyData = new Uint8Array(analyser.frequencyBinCount);
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analyser.getByteFrequencyData(frequencyData);
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frequencyOverTime.unshift(frequencyData);
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bitStart.unshift(false);
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if(frequencyOverTime.length > 1024) {
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frequencyOverTime.length = 1024;
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bitStart.length = 1024;
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}
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drawFrequencyData();
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function canHear(hz) {
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var length = (audioContext.sampleRate / analyser.fftSize);
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var i = Math.round(hz / length);
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return frequencyData[i] > FREQUENCY_THRESHOLD;
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}
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function amplitude(hz) {
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var length = (audioContext.sampleRate / analyser.fftSize);
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var i = Math.round(hz / length);
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return frequencyData[i];
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}
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const sum = (total, value) => total + value;
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function evaluateBit(highBits, lowBits) {
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let highCount = highBits.reduce(
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(count, highAmplitude, i) =>
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count += highAmplitude > lowBits[i] ? 1 : 0
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, 0
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);
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return highCount >= (highBits.length / 2) ? '1' : '0';
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}
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var high = canHear(FREQUENCY_HIGH);
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var low = canHear(FREQUENCY_LOW);
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const now = performance.now();
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if(high || low) {
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if(bitStarted) {
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if(now - bitStarted >= FREQUENCY_DURATION) {
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samplesPerBit.unshift(bitSampleCount)
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received(evaluateBit(bitHighStrength, bitLowStrength));
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bitHighStrength.length = 0;
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bitLowStrength.length = 0;
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bitStarted = now;
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bitStart[0] = true;
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bitSampleCount = 1;
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} else {
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bitSampleCount++;
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}
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} else {
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bitSampleCount = 1;
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bitStarted = now;
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bitStart[0] = true;
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bitHighStrength.length = 0;
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bitLowStrength.length = 0;
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}
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bitHighStrength.push(amplitude(FREQUENCY_HIGH));
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bitLowStrength.push(amplitude(FREQUENCY_LOW));
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} else {
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if(bitStarted) {
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// was bit long enough?
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const duration = now - bitStarted;
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if(duration >= FREQUENCY_DURATION * 0.6) {
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samplesPerBit.unshift(bitSampleCount)
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received(evaluateBit(bitHighStrength, bitLowStrength));
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}
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bitStarted = undefined;
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bitStart[0] = true;
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received('\n');
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}
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}
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if(samplesPerBit.length > 1024) {
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samplesPerBit.length = 1024;
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}
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samplesPerBitLabel.innerText = avgLabel(samplesPerBit);
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requestAnimationFrame(analyzeAudio);
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}
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function avgLabel(array) {
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const values = array.filter(v => v > 0);
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if(values.length === 0) return 'N/A';
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return (values.reduce((t, v) => t + v, 0) / values.length).toFixed(2)
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}
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function drawBitStart(ctx, color) {
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const { width, height } = receivedGraph;
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const segmentWidth = (1 / 1024) * width;
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ctx.strokeStyle = color;
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for(let i = 0; i < bitStart.length; i++) {
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if(!bitStart[i]) continue;
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ctx.beginPath();
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ctx.moveTo(segmentWidth * i, 0);
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ctx.lineTo(segmentWidth * i, height);
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ctx.stroke();
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}
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}
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function drawFrequency(ctx, hz, color) {
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const { width, height } = receivedGraph;
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const segmentWidth = (1 / 1024) * width;
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ctx.strokeStyle = color;
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ctx.beginPath();
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for(let i = 0; i < frequencyOverTime.length; i++) {
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const frequencies = frequencyOverTime[i];
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var length = (audioContext.sampleRate / analyser.fftSize);
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var index = Math.round(hz / length);
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const amplitude = frequencies[index];
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const y = (1-(amplitude / 255)) * height;
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if(i === 0) {
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ctx.moveTo(0, y);
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} else {
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ctx.lineTo(segmentWidth * i, y)
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}
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}
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ctx.stroke();
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}
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function drawFrequencyData() {
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const ctx = receivedGraph.getContext('2d');
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const { width, height } = receivedGraph;
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ctx.clearRect(0, 0, width, height);
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ctx.fillStyle = 'black';
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ctx.fillRect(0, 0, width, height);
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const thresholdY = (1 - (FREQUENCY_THRESHOLD/255)) * height;
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ctx.strokeStyle = 'grey';
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ctx.moveTo(0, thresholdY);
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ctx.lineTo(width, thresholdY);
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ctx.stroke();
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drawBitStart(ctx, 'grey');
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drawFrequency(ctx, FREQUENCY_HIGH, 'red');
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drawFrequency(ctx, FREQUENCY_LOW, 'blue');
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}
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function drawReceivedData() {
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const ctx = receivedGraph.getContext('2d');
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const { width, height } = receivedGraph;
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const segmentWidth = (1 / MAX_DATA_POINTS) * width;
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ctx.clearRect(0, 0, width, height);
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const sorted = receivedData.slice().sort((a, b) => a - b);
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const min = sorted[0];
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const max = sorted[sorted.length - 1];
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const range = max - min;
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ctx.beginPath();
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for(let i = 0; i < MAX_DATA_POINTS && i < receivedData.length; i++) {
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const value = receivedData[i];
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const y = (1-(value / range)) * height;
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if(i === 0) {
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ctx.moveTo(0, y);
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} else {
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ctx.lineTo(segmentWidth * i, y)
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}
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}
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ctx.stroke();
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}
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window.addEventListener('load', handleWindowLoad); |