loopback.html - Android社区 - https://www.androidos.net.cn/

<!DOCTYPE html>
<html>
<head><title>Loopback test</title></head>
<body>
  <video id="localVideo" width="1280" height="720" autoplay muted></video>
<script src="ssim.js"></script>
<script src="blackframe.js"></script>
<script>

var resolutions = [[640, 480],
                   [1280, 720]];
var results = {};
var testProgress = 0;
var durationMs = 20000;

function testNextResolution() {
  var nextResolution = resolutions.shift();
  if (nextResolution == undefined) {
    reportTestDone();
    return;
  }
  var test = new CameraTest(nextResolution);
  test.start();
  setTimeout(
    function() {
      test.stop();
      testNextResolution();
    },
    durationMs);
}


function reportTestDone() {
  console.log('tests completed');
  testProgress = 1;
}

function getResults() {
  return results;
}

function saveResult(resolution, verdict) {
  results[resolution] = verdict;
}

function CameraTest(resolution) {
  this.resolution = resolution;
  this.localVideo = document.getElementById("localVideo");
  this.localVideo.width = this.resolution[0].toString();
  this.localVideo.height = this.resolution[1].toString();
  this.localStream = null;
  this.video = document.querySelector('video');
  this.canvas = document.createElement('canvas');
  this.canvas.width = this.localVideo.width;
  this.canvas.height = this.localVideo.height;
  this.context = this.canvas.getContext('2d');
  this.previousFrame = [];
  this.identicalFrameSsimThreshold = 0.985;
  this.frameComparator = new Ssim();
  this.results = {cameraErrors: [],
      frameStats: {numBlackFrames: 0, numFrozenFrames:0, numFrames: 0}};
  this.constraints = {
    "audio": false,
    "video": {
      "mandatory" : {
     	  "maxWidth": this.resolution[0].toString(),
     	  "maxHeight": this.resolution[1].toString()
      },
    }
  };
}

CameraTest.prototype = {

  start: function() {
    this.localVideo.addEventListener('play',
        this.startCheckingVideoFrames.bind(this), false);
    navigator.getUserMedia = navigator.getUserMedia ||
        navigator.webkitGetUserMedia || navigator.mozGetUserMedia;

    navigator.getUserMedia(this.constraints, this.gotLocalStream.bind(this),
        this.gotUserMediaError.bind(this));
  },

  gotLocalStream: function(stream) {
    this.localStream = stream;
    this.localVideo.src = window.URL.createObjectURL(stream);
  },

  gotUserMediaError: function(error) {
    console.log('navigator.getUserMedia error: ', error);
    this.results.cameraErrors.push('GetUserMedia error: ' + error.toString());
  },

  startCheckingVideoFrames: function() {
    this.videoFrameChecker = setInterval(this.checkVideoFrame.bind(this), 20);
  },

  checkVideoFrame: function() {
    this.context.drawImage(this.localVideo, 0, 0, this.canvas.width,
      this.canvas.height);
    var imageData = this.context.getImageData(0, 0, this.canvas.width,
      this.canvas.height);

    if (isBlackFrame(imageData.data, imageData.data.length)) {
      this.results.frameStats.numBlackFrames++;
    }

    if (this.frameComparator.calculate(this.previousFrame, imageData.data) >
      this.identicalFrameSsimThreshold) {
      this.results.frameStats.numFrozenFrames++;
    }

    this.previousFrame = imageData.data;
    this.results.frameStats.numFrames++;
  },

  stop: function() {
    clearInterval(this.videoFrameChecker);
    saveResult(this.resolution, this.results);
    this.localStream.getTracks().forEach(function(track) {
      track.stop();
    });
    this.localVideo.src = null;
  },
}

window.onload = testNextResolution;
window.onerror = function (message, filename, lineno, colno, error) {
  console.log("Something went wrong, here is the stack trace --> %s",
      error.stack);
};
</script>
</body>
</html>