local-video-contraints-webrtc

var audioSource = "",videoSource = "";
function gotSources(sourceInfos) {
  for (var i = 0; i !== sourceInfos.length; ++i) {
    var sourceInfo = sourceInfos[i];
    //var option = document.createElement('option');
    //option.value = sourceInfo.id;
    if (sourceInfo.kind === 'audio') {
      //option.text = sourceInfo.label || 'microphone ' + (audioSelect.length + 1);
      audioSource = sourceInfo.id;
      console.log("mic:"+sourceInfo.id);
      //audioSelect.appendChild(option);
    } else if (sourceInfo.kind === 'video') {
      videoSource = sourceInfo.id;
      //option.text = sourceInfo.label || 'camera ' + (videoSelect.length + 1);
      //videoSelect.appendChild(option);
    } else {
      console.log('Some other kind of source: ', sourceInfo);
    }
  }
}

if (typeof MediaStreamTrack === 'undefined'){
  alert('This browser does not support MediaStreamTrack.\n\nTry Chrome Canary.');
} else {
  MediaStreamTrack.getSources(gotSources);
}


var constraints = {
    audio: {
      optional: [
        {googEchoCancellation:true},
        {googAutoGainControl:true}, 
        {googNoiseSuppression:true},
        {googHighpassFilter:true}, 
        {googAudioMirroring:false}, 
        {googNoiseSuppression2:true}, 
        {googEchoCancellation2:true}, 
        {googAutoGainControl2:true}, 
        {googDucking:false}, 
        {sourceId:audioSource}, 
        {chromeRenderToAssociatedSink:true}
      ]
    },
    video: {
      optional: [
      	{sourceId: videoSource},
      	{googNoiseReduction: true},
      	{googLeakyBucket: true},
      	{maxWidth: 100},
      	{maxHeight: 75},
      	{minFrameRate: 30},
      ]
    }
  };