Source: lib/polyfill/videoplaybackquality.js

  1. /**
  2.  * @license
  3.  * Copyright 2016 Google Inc.
  4.  *
  5.  * Licensed under the Apache License, Version 2.0 (the "License");
  6.  * you may not use this file except in compliance with the License.
  7.  * You may obtain a copy of the License at
  8.  *
  9.  *     http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  18. goog.provide('shaka.polyfill.VideoPlaybackQuality');
  20. goog.require('shaka.polyfill.register');
  23. /**
  24.  * @namespace shaka.polyfill.VideoPlaybackQuality
  25.  *
  26.  * @summary A polyfill to provide MSE VideoPlaybackQuality metrics.
  27.  * Many browsers do not yet provide this API, and Chrome currently provides
  28.  * similar data through individual prefixed attributes on HTMLVideoElement.
  29.  */
  32. /**
  33.  * Install the polyfill if needed.
  34.  */
  35. shaka.polyfill.VideoPlaybackQuality.install = function() {
  36.   if (!window.HTMLVideoElement) {
  37.     // Avoid errors on very old browsers.
  38.     return;
  39.   }
  41.   var proto = HTMLVideoElement.prototype;
  42.   if (proto.getVideoPlaybackQuality) {
  43.     // No polyfill needed.
  44.     return;
  45.   }
  47.   if ('webkitDroppedFrameCount' in proto) {
  48.     proto.getVideoPlaybackQuality =
  49.         shaka.polyfill.VideoPlaybackQuality.webkit_;
  50.   }
  51. };
  54. /**
  55.  * @this {HTMLVideoElement}
  56.  * @return {!VideoPlaybackQuality}
  57.  * @private
  58.  */
  59. shaka.polyfill.VideoPlaybackQuality.webkit_ = function() {
  60.   return {
  61.     'droppedVideoFrames': this.webkitDroppedFrameCount,
  62.     'totalVideoFrames': this.webkitDecodedFrameCount,
  63.     // Not provided by this polyfill:
  64.     'corruptedVideoFrames': 0,
  65.     'creationTime': NaN,
  66.     'totalFrameDelay': 0
  67.   };
  68. };
  71. shaka.polyfill.register(shaka.polyfill.VideoPlaybackQuality.install);