2019/lib/mse/mediaSourcePortability.js

/**
 * @license
 * Copyright 2018 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

'use strict';

// The code tries to wrap MediaSource with or without Webkit prefix.
function setupMsePortability(testSuiteVer) {
  var dlog = function() {
    var forward = window.dlog || console.log.bind(console);
    forward.apply(this, arguments);
  };

  // If we have both MediaSource and WebKitMediaSource, then it's likely we
  // have Chrome with the dual implementation. Then pick the one that is
  // specified by testSuiteVer.
  // If we only have the unprefixed version, then we can only choose that.
  if (window.MediaSource && window.WebKitMediaSource ||
      window.MediaSource && !window.WebKitMediaSource) {
    window.MediaSource.prototype.version = 'MSE-live';
    return;
  }

  // If we have MSE with webkit prefix
  if (window.WebKitMediaSource) {
    window.MediaSource = window.WebKitMediaSource;
    window.MediaSource.prototype.version = 'MSE-live-webkit';

    var cou = window.URL.createObjectURL;
    var creatingURL = false;
    window.URL.createObjectURL = function(obj) {
      if (!creatingURL) {
        creatingURL = true;
        var url = window.URL.createObjectURL(obj);
        creatingURL = false;
        return url;
      }
      return cou.call(this, obj);
    };

    var generateEventListener = function(elf) {
      return function(type, listener, useCaptures) {
        var re = /^source(open|close|ended)$/;
        var match = re.exec(type);
        if (match) {
          elf.call(this, 'webkit' + type, listener, useCaptures);
        } else {
          elf.call(this, type, listener, useCaptures);
        }
      };
    };

    window.MediaSource.prototype.addEventListener = generateEventListener(
        window.MediaSource.prototype.addEventListener);

    window.MediaSource.prototype.removeEventListener = generateEventListener(
        window.MediaSource.prototype.removeEventListener);

    return;
  }
}