lili/data-over-audio
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Build bit streams of data received

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This commit is contained in:
Lewis Moten
2024-05-01 01:15:13 -04:00
parent edfb3944fd
commit 89a72e3bce
1 changed files with 30 additions and 13 deletions
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43
index.js
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@@ -6,6 +6,7 @@ var microphoneStream;
var microphoneNode;
var analyser;
var receivedDataTextarea;
var sentDataTextArea;
var receivedGraph;
var receivedData = [];
var MAX_DATA_POINTS = 1024;
@@ -15,6 +16,7 @@ var FREQUENCY_TONE = 18000;
var FREQUENCY_HIGH = 900;
var FREQUENCY_LOW = 1200;
var FREQUENCY_DURATION = 100;
var FREQUENCY_THRESHOLD = 50;
function handleWindowLoad() {
// grab dom elements
@@ -23,6 +25,7 @@ function handleWindowLoad() {
receivedDataTextarea = document.getElementById('received-data');
receivedGraph = document.getElementById('received-graph');
textToSend = document.getElementById('text-to-send');
sentDataTextArea = document.getElementById('sent-data');
// wire up events
sendButton.addEventListener('click', handleSendButtonClick);
@@ -42,6 +45,8 @@ function getFrequency(bit) {
return bit ? FREQUENCY_HIGH : FREQUENCY_LOW;
}
function sendBits(bits) {
sentDataTextArea.value += bits.join('') + '\n';
sentDataTextArea.scrollTop = sentDataTextArea.scrollHeight;
var audioContext = getAudioContext();
var oscillator = audioContext.createOscillator();
var duration = bits.length * FREQUENCY_DURATION;
@@ -82,7 +87,7 @@ function handleListeningCheckbox(e) {
microphoneStream = stream;
microphoneNode = audioContext.createMediaStreamSource(stream);
analyser = audioContext.createAnalyser();
analyser.fftSize = 2048;
analyser.fftSize = 2 ** 12;
microphoneNode.connect(analyser);
requestAnimationFrame(analyzeAudio);
}
@@ -100,13 +105,18 @@ function handleListeningCheckbox(e) {
microphoneStream = undefined;
}
if(analyser && microphoneNode) {
analyser.disconnect(microphoneNode);
try {
analyser.disconnect(microphoneNode);
} catch(e) {
}
microphoneNode = undefined;
analyser = undefined;
}
}
}
let listen = '';
function analyzeAudio() {
if(!analyser) return;
if(!microphoneNode) return;
@@ -115,19 +125,26 @@ function analyzeAudio() {
analyser.getByteFrequencyData(frequencyData);
drawFrequencyData(frequencyData);
var frequencyIndex = Math.round(FREQUENCY_TONE / (audioContext.sampleRate / analyser.fftSize));
const amplitude = frequencyData[frequencyIndex];
receivedData.unshift(amplitude);
if(receivedData.length > MAX_DATA_POINTS) {
receivedData.length = MAX_DATA_POINTS;
}
// drawReceivedData();
if(amplitude > 0) {
receivedDataTextarea.value = `Frequency ${FREQUENCY_TONE}Hz Detected. Amplitude: ${amplitude}`;
} else {
receivedDataTextarea.value = `Frequency ${FREQUENCY_TONE}Hz Not Detected.`;
function canHear(hz) {
var length = (audioContext.sampleRate / analyser.fftSize);
var i = Math.round(hz / length);
return frequencyData[i] > FREQUENCY_THRESHOLD;
}
var high = canHear(FREQUENCY_HIGH);
var low = canHear(FREQUENCY_LOW);
if(high || low) {
if(high && low) listen += '[';
if(high) listen += '1';
if(low) listen += '0';
if(high && low) listen += ']';
} else {
if(listen !== '') {
receivedDataTextarea.value += listen + '\n';
receivedDataTextarea.scrollTop = receivedDataTextarea.scrollHeight;
}
listen = '';
}
requestAnimationFrame(analyzeAudio);
}