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 }; 68
