media/test/data/eme_player_js/fps_observer.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // FPSObserver observes a <video> and reports decoded FPS, dropped FPS, and
   6 // total dropped frames during the video playback.
   7 var FPSObserver = new function() {
   8   this.video_ = null;
   9   this.decodedFrames_ = 0;
  10   this.droppedFrames_ = 0;
  11   this.startTime_ = 0;
  12   this.intID_ = null;
  13 }
  14
  15 FPSObserver.observe = function(video) {
  16   this.video_ = video;
  17   var observer = this;
  18   this.video_.addEventListener('playing', function() {
  19     observer.onVideoPlaying();
  20   });
  21
  22   this.video_.addEventListener('error', function() {
  23     observer.endTest();
  24   });
  25
  26   this.video_.addEventListener('ended', function() {
  27     observer.endTest();
  28   });
  29 };
  30
  31 FPSObserver.onVideoPlaying = function() {
  32   this.decodedFrames_ = 0;
  33   this.droppedFrames_ = 0;
  34   this.startTime_ = window.performance.now();
  35   this.endTest(true);
  36   var observer = this;
  37   this.intID_ = window.setInterval(function() {
  38       observer.calculateStats();}, 1000);
  39 };
  40
  41 FPSObserver.calculateStats = function() {
  42   if (this.video_.readyState <= HTMLMediaElement.HAVE_CURRENT_DATA ||
  43       this.video_.paused || this.video_.ended)
  44     return;
  45   var currentTime = window.performance.now();
  46   var deltaTime = (currentTime - this.startTime_) / 1000;
  47   this.startTime_ = currentTime;
  48
  49   // Calculate decoded frames per sec.
  50   var fps = (this.video_.webkitDecodedFrameCount - this.decodedFrames_) /
  51              deltaTime;
  52   this.decodedFrames_ = this.video_.webkitDecodedFrameCount;
  53   fps = fps.toFixed(2);
  54   decodedFPSElement.innerHTML = fps;
  55
  56   // Calculate dropped frames per sec.
  57   fps = (this.video_.webkitDroppedFrameCount - this.droppedFrames_) / deltaTime;
  58   this.droppedFrames_ = this.video_.webkitDroppedFrameCount;
  59   fps = fps.toFixed(2);
  60   droppedFPSElement.innerHTML = fps;
  61
  62   droppedFramesElement.innerHTML = this.droppedFrames_;
  63 };
  64
  65 FPSObserver.endTest = function() {
  66   window.clearInterval(this.intID_);
  67 };