audio input

var ac = new webkitAudioContext();
var cap = {};
navigator.webkitGetUserMedia({audio: true}, function(stream) {
    cap.mic = ac.createMediaStreamSource(stream);
}, null);
// 여기까지 일단 실행하고~ 마이크 입력을 허락해 주고.
var analyser = ac.createAnalyser();
var buff = new Uint8Array(analyser.frequencyBinCount);
var g = document.createElement('canvas').getContext('2d');
g.canvas.width = 512;
g.canvas.height = 256;
document.body.appendChild(g.canvas);
cap.mic.connect(analyser);

var update = function() {
    var i, x, y;
    g.clearRect(0, 0, g.canvas.width, g.canvas.height);
    analyser.getByteTimeDomainData(buff);
    y = g.canvas.height * 0.5;
    for(i = 0; i < buff.length; i++) {
        x = i / buff.length * g.canvas.width;
        g.beginPath();
        g.moveTo(x, y);
        g.lineTo(x, y + (buff[i] / 255 - 0.5) * g.canvas.height);
        g.stroke();
    }
};

var loop = function() {
    update();
    webkitRequestAnimationFrame(loop);
};

loop();