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Analyze the frequency of the sound from the microphone
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>Frequency Analyser - Web Audio API Demo</title> | |
| </head> | |
| <body> | |
| <canvas id="theCanvas" width="1024" height="256"></canvas> <br/> | |
| <button id="startButton" type="button">Start</button> | |
| <script> | |
| (function() { | |
| var AudioContext = window.AudioContext || window.webkitAudioContext; | |
| var mediaStreamSource; | |
| var analyser; | |
| var canvas = document.querySelector('#theCanvas'); | |
| var canvasContext = canvas.getContext("2d"); | |
| var dataArray; | |
| canvasWidth = canvas.width; | |
| canvasHeight = canvas.height; | |
| navigator.getUserMedia = (navigator.getUserMedia || | |
| navigator.webkitGetUserMedia || | |
| navigator.mozGetUserMedia || | |
| navigator.msGetUserMedia); | |
| if (navigator.getUserMedia) { | |
| var audioContext = new AudioContext(); | |
| document.querySelector("#startButton").addEventListener('click', startButton_Clicked); | |
| function gotStream(stream) { | |
| var audioContext = new AudioContext(); | |
| mediaStreamSource = audioContext.createMediaStreamSource(stream); | |
| analyser = audioContext.createAnalyser(); | |
| mediaStreamSource.connect(analyser); | |
| startDrawing(); | |
| } | |
| function startButton_Clicked() { | |
| this.disabled = true; | |
| navigator.getUserMedia( {audio:true}, gotStream, error); | |
| } | |
| function startDrawing() { | |
| analyser.fftSize = 2048; | |
| var bufferLength = analyser.frequencyBinCount; | |
| console.log(bufferLength); | |
| dataArray = new Uint8Array(bufferLength); | |
| function drawAgain() { | |
| canvasContext.clearRect(0, 0, canvasWidth, canvasWidth); | |
| requestAnimationFrame(drawAgain); | |
| analyser.getByteFrequencyData(dataArray); | |
| for(var i = 0; i < bufferLength; i++){ | |
| canvasContext.beginPath(); | |
| canvasContext.moveTo(i, 255); | |
| canvasContext.lineTo(i, 255 - dataArray[i]); | |
| canvasContext.closePath(); | |
| canvasContext.stroke(); | |
| } | |
| } | |
| drawAgain(); | |
| } | |
| function error(message) { | |
| console.log(message); | |
| } | |
| } else { | |
| document.querySelector("#startButton").disabled = true; | |
| alert("Sorry, you can't use the mic in this web browser. Try the latest version of Firefox, Chrome or Opera."); | |
| } | |
| })(); | |
| </script> | |
| </body> | |
| </html> |
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