average volume reporter

gistfile1.txt

 function start() {
    navigator.mediaDevices.getUserMedia({ audio: true})
      .then(onMediaStreamHandler)
      .catch(function(error) {
        console.log('getUserMedia error: ', err);
      });
  }

  function onMediaStreamHandler(stream) {
    stream.onactive = function(e) { console.log('stream active', e) };
    stream.onaddtrack = function(e) { console.log('stream track added', e) };
    stream.onended = function(e) { console.log('stream ended', e) };
    stream.oninactive = function(e) { console.log('stream inactive', e) };
    stream.onremovetrack = function(e) { console.log('stream track removed', e) };
    
    var audioCtx = new AudioContext();

    var analyser = audioCtx.createAnalyser();
    analyser.minDecibels = -90;
    analyser.maxDecibels = -10;
    analyser.smoothingTimeConstant = 0.85;

    var source = audioCtx.createMediaStreamSource(stream);
    source.connect(analyser);

    var gainNode = audioCtx.createGain();
    gainNode.connect(audioCtx.destination);

    var bufferLength = analyser.fftSize;
    var dataArray = new Uint8Array(analyser.frequencyBinCount);

    var rAFHandle = null,
        avgVolume = 0,
        lastVolume = 0;

    (function draw() {
      rAFHandle = requestAnimationFrame(draw);
      analyser.getByteFrequencyData(dataArray);
      avgVolume = getAverageVolume(dataArray);
    })();

    setInterval(function() {
      console.log('avgvol', avgVolume)

      lastVolume = avgVolume
    }, 1000);

    function getAverageVolume(data) {
      return data.reduce(function(sum, value){
        return sum + value;
      }, 0) / data.length;
    }
  }