I would like some advice on how best to get the microphone activity level of an audio MediaStreamTrack
javascript object in Chrome/Canary. The MediaStreamTrack
object is an audio track of the MediaStream
returned by getUserMedia
, as part of the WebRTC javascript API.
When microphone has audio the green bar up and down very nice:
<script type="text/javascript">
navigator.webkitGetUserMedia({audio:true, video:true}, function(stream){
// audioContext = new webkitAudioContext(); deprecated OLD!!
audioContext = new AudioContext(); // NEW!!
analyser = audioContext.createAnalyser();
microphone = audioContext.createMediaStreamSource(stream);
javascriptNode = audioContext.createJavaScriptNode(2048, 1, 1);
analyser.smoothingTimeConstant = 0.3;
analyser.fftSize = 1024;
microphone.connect(analyser);
analyser.connect(javascriptNode);
javascriptNode.connect(audioContext.destination);
//canvasContext = $("#canvas")[0].getContext("2d");
canvasContext = document.getElementById("test");
canvasContext= canvasContext.getContext("2d");
javascriptNode.onaudioprocess = function() {
var array = new Uint8Array(analyser.frequencyBinCount);
analyser.getByteFrequencyData(array);
var values = 0;
var length = array.length;
for (var i = 0; i < length; i++) {
values += array[i];
}
var average = values / length;
canvasContext.clearRect(0, 0, 60, 130);
canvasContext.fillStyle = '#00ff00';
canvasContext.fillRect(0,130-average,25,130);
}
}
);
</script>
<canvas id="test" style="background-color: black;"></canvas>