shaka-player/lib/player.js

/**
 * @license
 * Copyright 2016 Google Inc.
 *
 * 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.
 */

goog.provide('shaka.Player');

goog.require('goog.asserts');
goog.require('shaka.abr.SimpleAbrManager');
goog.require('shaka.log');
goog.require('shaka.media.DrmEngine');
goog.require('shaka.media.ManifestParser');
goog.require('shaka.media.MediaSourceEngine');
goog.require('shaka.media.Playhead');
goog.require('shaka.media.SegmentReference');
goog.require('shaka.media.StreamingEngine');
goog.require('shaka.net.NetworkingEngine');
goog.require('shaka.util.CancelableChain');
goog.require('shaka.util.ConfigUtils');
goog.require('shaka.util.Error');
goog.require('shaka.util.EventManager');
goog.require('shaka.util.FakeEvent');
goog.require('shaka.util.FakeEventTarget');
goog.require('shaka.util.IDestroyable');
goog.require('shaka.util.MapUtils');
goog.require('shaka.util.PublicPromise');
goog.require('shaka.util.StreamUtils');



/**
 * Construct a Player.
 *
 * @param {!HTMLMediaElement} video Any existing TextTracks attached to this
 *   element that were not created by Shaka will be disabled.  A new TextTrack
 *   may be created to display captions or subtitles.
 * @param {function(shaka.Player)=} opt_dependencyInjector Optional callback
 *   which is called to inject mocks into the Player. Used for testing.
 *
 * @constructor
 * @struct
 * @implements {shaka.util.IDestroyable}
 * @extends {shaka.util.FakeEventTarget}
 * @export
 */
shaka.Player = function(video, opt_dependencyInjector) {
  shaka.util.FakeEventTarget.call(this);

  /** @private {boolean} */
  this.destroyed_ = false;

  /** @private {HTMLMediaElement} */
  this.video_ = video;

  /** @private {TextTrack} */
  this.textTrack_ = null;

  /** @private {shaka.util.EventManager} */
  this.eventManager_ = new shaka.util.EventManager();

  /** @private {shakaExtern.AbrManager} */
  this.defaultAbrManager_ = new shaka.abr.SimpleAbrManager();

  /** @private {shaka.net.NetworkingEngine} */
  this.networkingEngine_ = null;

  /** @private {shaka.media.DrmEngine} */
  this.drmEngine_ = null;

  /** @private {MediaSource} */
  this.mediaSource_ = null;

  /** @private {shaka.media.MediaSourceEngine} */
  this.mediaSourceEngine_ = null;

  /** @private {Promise} */
  this.mediaSourceOpen_ = null;

  /** @private {shaka.media.Playhead} */
  this.playhead_ = null;

  /** @private {shaka.media.StreamingEngine} */
  this.streamingEngine_ = null;

  /** @private {shakaExtern.ManifestParser} */
  this.parser_ = null;

  /** @private {?shakaExtern.Manifest} */
  this.manifest_ = null;

  /** @private {?string} */
  this.manifestUri_ = null;

  /**
   * Contains an ID for use with creating streams.  The manifest parser should
   * start with small IDs, so this starts with a large one.
   * @private {number}
   */
  this.nextExternalStreamId_ = 1e9;

  /** @private {!Array.<number>} */
  this.loadingTextStreamIds_ = [];

  /** @private {boolean} */
  this.buffering_ = false;

  /** @private {boolean} */
  this.switchingPeriods_ = true;

  /** @private {shaka.util.CancelableChain} */
  this.loadChain_ = null;

  /**
   * @private {!Object.<string, {stream: shakaExtern.Stream, clear: boolean}>}
   */
  this.deferredSwitches_ = {};

  /** @private {?shakaExtern.PlayerConfiguration} */
  this.config_ = this.defaultConfig_();

  /** @private {{width: number, height: number}} */
  this.maxHwRes_ = { width: Infinity, height: Infinity };

  /** @private {!Array.<shakaExtern.StreamChoice>} */
  this.switchHistory_ = [];

  /** @private {number} */
  this.playTime_ = 0;

  /** @private {number} */
  this.bufferingTime_ = 0;

  /** @private {number} */
  this.lastStatUpdateTimestamp_ = 0;

  if (opt_dependencyInjector)
    opt_dependencyInjector(this);

  this.networkingEngine_ = this.createNetworkingEngine();
  this.initialize_();
};
goog.inherits(shaka.Player, shaka.util.FakeEventTarget);


/**
 * After destruction, a Player object cannot be used again.
 *
 * @override
 * @export
 */
shaka.Player.prototype.destroy = function() {
  this.destroyed_ = true;

  var cancelation = Promise.resolve();
  if (this.loadChain_) {
    // A load is in progress.  Cancel it.
    cancelation = this.loadChain_.cancel(new shaka.util.Error(
        shaka.util.Error.Category.PLAYER,
        shaka.util.Error.Code.LOAD_INTERRUPTED));
  }

  return cancelation.then(function() {
    var p = Promise.all([
      this.destroyStreaming_(),
      this.eventManager_ ? this.eventManager_.destroy() : null,
      this.networkingEngine_ ? this.networkingEngine_.destroy() : null
    ]);

    this.video_ = null;
    this.textTrack_ = null;
    this.eventManager_ = null;
    this.defaultAbrManager_ = null;
    this.networkingEngine_ = null;
    this.config_ = null;

    return p;
  }.bind(this));
};


/**
 * @define {string} A version number taken from git at compile time.
 */
goog.define('GIT_VERSION', 'v2.0.0-beta2-debug');


/**
 * @const {string}
 * @export
 */
shaka.Player.version = GIT_VERSION;


/**
 * @event shaka.Player.ErrorEvent
 * @description Fired when a playback error occurs.
 * @property {string} type
 *   'error'
 * @property {!shaka.util.Error} detail
 *   An object which contains details on the error.  The error's 'category' and
 *   'code' properties will identify the specific error that occured.  In an
 *   uncompiled build, you can also use the 'message' and 'stack' properties
 *   to debug.
 * @exportDoc
 */


/**
 * @event shaka.Player.BufferingEvent
 * @description Fired when the player's buffering state changes.
 * @property {string} type
 *   'buffering'
 * @property {boolean} buffering
 *   True when the Player enters the buffering state.
 *   False when the Player leaves the buffering state.
 * @exportDoc
 */


/**
 * @event shaka.Player.LoadingEvent
 * @description Fired when the player begins loading.
 *   Used by the Cast receiver to determine idle state.
 * @property {string} type
 *   'loading'
 * @exportDoc
 */


/**
 * @event shaka.Player.UnloadingEvent
 * @description Fired when the player unloads or fails to load.
 *   Used by the Cast receiver to determine idle state.
 * @property {string} type
 *   'unloading'
 * @exportDoc
 */


/**
 * @event shaka.Player.TextTrackVisibilityEvent
 * @description Fired when text track visibility changes.
 * @property {string} type
 *   'texttrackvisibility'
 * @exportDoc
 */


/**
 * @event shaka.Player.TracksChangedEvent
 * @description Fired when the list of tracks changes.  For example, this will
 *   happen when changing periods or when track restrictions change.
 * @property {string} type
 *   'trackschanged'
 * @exportDoc
 */


/**
 * @event shaka.Player.AdaptationEvent
 * @description Fired when an automatic adaptation causes the active tracks
 *   to change.  Does not fire when the application calls selectTrack().
 * @property {string} type
 *   'adaptation'
 * @exportDoc
 */


/** @private {!Object.<string, function():*>} */
shaka.Player.supportPlugins_ = {};


/**
 * Registers a plugin callback that will be called with support().  The
 * callback will return the value that will be stored in the return value from
 * support().
 *
 * @param {string} name
 * @param {function():*} callback
 * @export
 */
shaka.Player.registerSupportPlugin = function(name, callback) {
  shaka.Player.supportPlugins_[name] = callback;
};


/**
 * Return whether the browser provides basic support. If this returns false,
 * Shaka Player cannot be used at all. In this case, do not construct a Player
 * instance and do not use the library.
 *
 * @return {boolean}
 * @export
 */
shaka.Player.isBrowserSupported = function() {
  // Basic features needed for the library to be usable.
  var basic = !!window.Promise && !!window.Uint8Array &&
              !!Array.prototype.forEach;

  return basic &&
      shaka.media.MediaSourceEngine.isBrowserSupported() &&
      shaka.media.DrmEngine.isBrowserSupported();
};


/**
 * Probes the browser to determine what features are supported.  This makes a
 * number of requests to EME/MSE/etc which may result in user prompts.  This
 * should only be used for diagnostics.
 *
 * NOTE: This may show a request to the user for permission.
 *
 * @see https://goo.gl/ovYLvl
 * @return {!Promise.<shakaExtern.SupportType>}
 * @export
 */
shaka.Player.probeSupport = function() {
  goog.asserts.assert(shaka.Player.isBrowserSupported(),
                      'Must have basic support');
  return shaka.media.DrmEngine.probeSupport().then(function(drm) {
    var manifest = shaka.media.ManifestParser.probeSupport();
    var media = shaka.media.MediaSourceEngine.probeSupport();
    var ret = {
      manifest: manifest,
      media: media,
      drm: drm
    };

    var plugins = shaka.Player.supportPlugins_;
    for (var name in plugins) {
      ret[name] = plugins[name]();
    }

    return ret;
  });
};


/**
 * Load a manifest.
 *
 * @param {string} manifestUri
 * @param {number=} opt_startTime Optional start time, in seconds, to begin
 *   playback.  Defaults to 0 for VOD and to the live edge for live.
 * @param {shakaExtern.ManifestParser.Factory=} opt_manifestParserFactory
 *   Optional manifest parser factory to override auto-detection or use an
 *   unregistered parser.
 * @return {!Promise} Resolved when the manifest has been loaded and playback
 *   has begun; rejected when an error occurs or the call was interrupted by
 *   destroy(), unload() or another call to load().
 * @export
 */
shaka.Player.prototype.load = function(manifestUri, opt_startTime,
                                       opt_manifestParserFactory) {
  var unloadPromise = this.unload();
  var loadChain = new shaka.util.CancelableChain();
  this.loadChain_ = loadChain;
  this.dispatchEvent(new shaka.util.FakeEvent('loading'));

  return loadChain.then(function() {
    return unloadPromise;
  }).then(function() {

    goog.asserts.assert(this.networkingEngine_, 'Must not be destroyed');
    return shaka.media.ManifestParser.getFactory(
        manifestUri,
        this.networkingEngine_,
        this.config_.manifest.retryParameters,
        opt_manifestParserFactory);
  }.bind(this)).then(function(factory) {

    this.parser_ = new factory();
    this.parser_.configure(this.config_.manifest);
    goog.asserts.assert(this.networkingEngine_, 'Must not be destroyed');
    return this.parser_.start(
        manifestUri,
        this.networkingEngine_,
        this.filterPeriod_.bind(this),
        this.onError_.bind(this));
  }.bind(this)).then(function(manifest) {

    this.manifest_ = manifest;
    this.manifestUri_ = manifestUri;
    this.drmEngine_ = this.createDrmEngine();
    this.drmEngine_.configure(this.config_.drm);
    return this.drmEngine_.init(manifest, false /* isOffline */);
  }.bind(this)).then(function() {

    // Re-filter the manifest after DRM has been initialized.
    this.manifest_.periods.forEach(this.filterPeriod_.bind(this));

    this.lastStatUpdateTimestamp_ = Date.now() / 1000;

    // Wait for MediaSource to open before continuing.
    return Promise.all([
      this.drmEngine_.attach(this.video_),
      this.mediaSourceOpen_
    ]);
  }.bind(this)).then(function() {

    // MediaSource is open, so create the Playhead, MediaSourceEngine, and
    // StreamingEngine.
    this.playhead_ = this.createPlayhead(opt_startTime);
    this.mediaSourceEngine_ = this.createMediaSourceEngine();

    this.streamingEngine_ = this.createStreamingEngine();
    this.streamingEngine_.configure(this.config_.streaming);
    return this.streamingEngine_.init();
  }.bind(this)).then(function() {

    // Re-filter the manifest after streams have been chosen.
    this.manifest_.periods.forEach(this.filterPeriod_.bind(this));
    // Dispatch a 'trackschanged' event now that all initial filtering is done.
    this.onTracksChanged_();
    // Since the first streams just became active, send an adaptation event.
    this.onAdaptation_();

    this.config_.abr.manager.init(this.switch_.bind(this));

    this.loadChain_ = null;
  }.bind(this)).finalize().catch(function(error) {
    goog.asserts.assert(error instanceof shaka.util.Error,
                        'Wrong error type!');
    shaka.log.debug('load() failed:', error);

    // If we haven't started another load, clear the loadChain_ member.
    if (this.loadChain_ == loadChain) {
      this.loadChain_ = null;
      this.dispatchEvent(new shaka.util.FakeEvent('unloading'));
    }
    return Promise.reject(error);
  }.bind(this));
};


/**
 * Creates a new instance of DrmEngine.  This can be replaced by tests to
 * create fake instances instead.
 *
 * @return {!shaka.media.DrmEngine}
 */
shaka.Player.prototype.createDrmEngine = function() {
  goog.asserts.assert(this.networkingEngine_, 'Must not be destroyed');
  return new shaka.media.DrmEngine(
      this.networkingEngine_,
      this.onError_.bind(this),
      this.onKeyStatus_.bind(this));
};


/**
 * Creates a new instance of NetworkingEngine.  This can be replaced by tests
 * to create fake instances instead.
 *
 * @return {!shaka.net.NetworkingEngine}
 */
shaka.Player.prototype.createNetworkingEngine = function() {
  return new shaka.net.NetworkingEngine(this.onSegmentDownloaded_.bind(this));
};


/**
 * Creates a new instance of Playhead.  This can be replaced by tests to create
 * fake instances instead.
 *
 * @param {number=} opt_startTime
 * @return {!shaka.media.Playhead}
 */
shaka.Player.prototype.createPlayhead = function(opt_startTime) {
  var timeline = this.manifest_.presentationTimeline;
  var rebufferingGoal = shaka.media.StreamingEngine.getRebufferingGoal(
      this.manifest_, this.config_.streaming, 1 /* scaleFactor */);
  return new shaka.media.Playhead(
      this.video_, timeline, rebufferingGoal, opt_startTime || null,
      this.onBuffering_.bind(this), this.onSeek_.bind(this));
};


/**
 * Create and open MediaSource.  Potentially slow.
 *
 * @return {!Promise}
 */
shaka.Player.prototype.createMediaSource = function() {
  this.mediaSource_ = new MediaSource();
  var ret = new shaka.util.PublicPromise();
  this.eventManager_.listen(this.mediaSource_, 'sourceopen', ret.resolve);
  this.video_.src = window.URL.createObjectURL(this.mediaSource_);
  return ret;
};


/**
 * Creates a new instance of MediaSourceEngine.  This can be replaced by tests
 * to create fake instances instead.
 *
 * @return {!shaka.media.MediaSourceEngine}
 */
shaka.Player.prototype.createMediaSourceEngine = function() {
  return new shaka.media.MediaSourceEngine(
      this.video_, this.mediaSource_, this.textTrack_);
};


/**
 * Creates a new instance of StreamingEngine.  This can be replaced by tests
 * to create fake instances instead.
 *
 * @return {!shaka.media.StreamingEngine}
 */
shaka.Player.prototype.createStreamingEngine = function() {
  goog.asserts.assert(this.playhead_, 'Must not be destroyed');
  goog.asserts.assert(this.mediaSourceEngine_, 'Must not be destroyed');
  goog.asserts.assert(this.manifest_, 'Must not be destroyed');
  return new shaka.media.StreamingEngine(
      this.playhead_, this.mediaSourceEngine_, this.networkingEngine_,
      this.manifest_, this.onChooseStreams_.bind(this),
      this.canSwitch_.bind(this), this.onError_.bind(this));
};


/**
 * Configure the Player instance.
 *
 * The config object passed in need not be complete.  It will be merged with
 * the existing Player configuration.
 *
 * Config keys and types will be checked.  If any problems with the config
 * object are found, errors will be reported through logs.
 *
 * @param {shakaExtern.PlayerConfiguration} config
 * @export
 */
shaka.Player.prototype.configure = function(config) {
  goog.asserts.assert(this.config_, 'Config must not be null!');

  if (config.abr && config.abr.manager &&
      config.abr.manager != this.config_.abr.manager) {
    this.config_.abr.manager.stop();
    config.abr.manager.init(this.switch_.bind(this));
  }

  shaka.util.ConfigUtils.mergeConfigObjects(
      this.config_, config, this.defaultConfig_(), this.configOverrides_(), '');

  this.applyConfig_();
};


/**
 * Apply config changes.
 * @private
 */
shaka.Player.prototype.applyConfig_ = function() {
  if (this.parser_) {
    this.parser_.configure(this.config_.manifest);
  }
  if (this.drmEngine_) {
    this.drmEngine_.configure(this.config_.drm);
  }
  if (this.streamingEngine_) {
    this.streamingEngine_.configure(this.config_.streaming);

    // Need to apply the restrictions to every period.
    this.manifest_.periods.forEach(this.filterPeriod_.bind(this));

    // May need to choose new streams.
    shaka.log.debug('Choosing new streams after changing configuration');
    var period = this.streamingEngine_.getCurrentPeriod();
    this.chooseStreamsAndSwitch_(period);
  }

  // Simply enable/disable ABR with each call, since multiple calls to these
  // methods have no effect.
  if (this.config_.abr.enabled && !this.switchingPeriods_) {
    this.config_.abr.manager.enable();
  } else {
    this.config_.abr.manager.disable();
  }

  this.config_.abr.manager.setDefaultEstimate(
      this.config_.abr.defaultBandwidthEstimate);
};


/**
 * Return a copy of the current configuration.  Modifications of the returned
 * value will not affect the Player's active configuration.  You must call
 * player.configure() to make changes.
 *
 * @return {shakaExtern.PlayerConfiguration}
 * @export
 */
shaka.Player.prototype.getConfiguration = function() {
  goog.asserts.assert(this.config_, 'Config must not be null!');

  var ret = this.defaultConfig_();
  shaka.util.ConfigUtils.mergeConfigObjects(
      ret, this.config_, this.defaultConfig_(), this.configOverrides_(), '');
  return ret;
};


/**
 * Reset configuration to default.
 * @export
 */
shaka.Player.prototype.resetConfiguration = function() {
  var config = this.defaultConfig_();

  if (config.abr && config.abr.manager &&
      config.abr.manager != this.config_.abr.manager) {
    this.config_.abr.manager.stop();
    config.abr.manager.init(this.switch_.bind(this));
  }

  // Don't call mergeConfigObjects_(), since that would not reset open-ended
  // dictionaries like drm.servers.
  this.config_ = this.defaultConfig_();

  this.applyConfig_();
};


/**
 * @return {shaka.net.NetworkingEngine} A reference to the Player's networking
 *     engine.  Applications may use this to make requests through Shaka's
 *     networking plugins.
 * @export
 */
shaka.Player.prototype.getNetworkingEngine = function() {
  return this.networkingEngine_;
};


/**
 * @return {?string} If a manifest is loaded, returns the manifest URI given in
 *   the last call to load().  Otherwise, returns null.
 * @export
 */
shaka.Player.prototype.getManifestUri = function() {
  return this.manifestUri_;
};


/**
 * @return {boolean} True if the current stream is live.  False if the stream is
 *     VOD or if there is no active stream.
 * @export
 */
shaka.Player.prototype.isLive = function() {
  return this.manifest_ ?
         this.manifest_.presentationTimeline.isLive() :
         false;
};


/**
 * Get the seekable range for the current stream.
 * @return {{start: number, end: number}}
 * @export
 */
shaka.Player.prototype.seekRange = function() {
  var start = 0;
  var end = 0;
  if (this.manifest_) {
    var timeline = this.manifest_.presentationTimeline;
    start = timeline.getSegmentAvailabilityStart();
    end = timeline.getSeekRangeEnd();
  }
  return {'start': start, 'end': end};
};


/**
 * Get the key system currently being used by EME.  This returns the empty
 * string if not using EME.
 *
 * @return {string}
 * @export
 */
shaka.Player.prototype.keySystem = function() {
  return this.drmEngine_ ? this.drmEngine_.keySystem() : '';
};


/**
 * Get the DrmInfo used to initialize EME.  This returns null when not using
 * EME.
 *
 * @return {?shakaExtern.DrmInfo}
 * @export
 */
shaka.Player.prototype.drmInfo = function() {
  return this.drmEngine_ ? this.drmEngine_.getDrmInfo() : null;
};


/**
 * @return {boolean} True if the Player is in a buffering state.
 * @export
 */
shaka.Player.prototype.isBuffering = function() {
  return this.buffering_;
};


/**
 * Unload the current manifest and make the Player available for re-use.
 *
 * @return {!Promise} Resolved when streaming has stopped and the previous
 *     content, if any, has been unloaded.
 * @export
 */
shaka.Player.prototype.unload = function() {
  if (this.destroyed_) return Promise.resolve();
  this.dispatchEvent(new shaka.util.FakeEvent('unloading'));

  if (this.loadChain_) {
    // A load is in progress.  Cancel it, then reset the streaming system.
    var interrupt = new shaka.util.Error(
        shaka.util.Error.Category.PLAYER,
        shaka.util.Error.Code.LOAD_INTERRUPTED);
    return this.loadChain_.cancel(interrupt)
        .then(this.resetStreaming_.bind(this));
  } else {
    // No loads or unloads are in progress.
    // Just reset the streaming system if needed.
    return this.resetStreaming_();
  }
};


/**
 * Gets the current effective playback rate.  If using trick play, it will
 * return the current trick play rate; otherwise, it will return the video
 * playback rate.
 * @return {number}
 * @export
 */
shaka.Player.prototype.getPlaybackRate = function() {
  return this.playhead_ ? this.playhead_.getPlaybackRate() : 0;
};


/**
 * Skip through the content without playing.  Simulated using repeated seeks.
 *
 * Trick play will be canceled automatically if the playhead hits the beginning
 * or end of the seekable range for the content.
 *
 * @param {number} rate The playback rate to simulate.  For example, a rate of
 *     2.5 would result in 2.5 seconds of content being skipped every second.
 *     To trick-play backward, use a negative rate.
 * @export
 */
shaka.Player.prototype.trickPlay = function(rate) {
  if (this.playhead_)
    this.playhead_.setPlaybackRate(rate);
};


/**
 * Cancel trick-play.
 * @export
 */
shaka.Player.prototype.cancelTrickPlay = function() {
  if (this.playhead_)
    this.playhead_.setPlaybackRate(1);
};


/**
 * Return a list of audio, video, and text tracks available for the current
 * Period.  If there are multiple Periods, then you must seek to the Period
 * before being able to switch.
 *
 * @return {!Array.<shakaExtern.Track>}
 * @export
 */
shaka.Player.prototype.getTracks = function() {
  if (!this.streamingEngine_)
    return [];

  var activeStreams = this.streamingEngine_.getActiveStreams();
  var period = this.streamingEngine_.getCurrentPeriod();
  return shaka.util.StreamUtils.getTracks(period, activeStreams)
      .filter(function(track) {
        // Don't show any tracks that are being loaded still.
        return this.loadingTextStreamIds_.indexOf(track.id) < 0;
      }.bind(this));
};


/**
 * Select a specific track.  For audio or video, this disables adaptation.
 * Note that AdaptationEvents are not fired for manual track selections.
 *
 * @param {shakaExtern.Track} track
 * @param {boolean=} opt_clearBuffer
 * @export
 */
shaka.Player.prototype.selectTrack = function(track, opt_clearBuffer) {
  if (!this.streamingEngine_)
    return;

  var period = this.streamingEngine_.getCurrentPeriod();
  var data = shaka.util.StreamUtils.findStreamForTrack(period, track);
  if (!data) {
    shaka.log.error('Unable to find the track with id "' + track.id +
                    '"; did we change Periods?');
    return;
  }
  var stream = data.stream;

  // Double check that the track is allowed to be played.
  if (!stream.allowedByApplication || !stream.allowedByKeySystem) {
    shaka.log.error('Unable to switch to track with id "' + track.id +
                    '" because it is restricted.');
    return;
  }

  // Add an entry to the history.
  this.switchHistory_.push({
    timestamp: Date.now() / 1000,
    id: stream.id,
    type: track.type,
    fromAdaptation: false
  });

  if (track.type != 'text') {
    // Disable ABR for anything other than text track changes.
    var config = /** @type {shakaExtern.PlayerConfiguration} */ (
        {abr: {enabled: false}});
    this.configure(config);
  }

  var streamsToSwitch = {};
  streamsToSwitch[track.type] = stream;
  this.deferredSwitch_(streamsToSwitch, opt_clearBuffer);
};


/**
 * @return {boolean} True if the current text track is visible.
 * @export
 */
shaka.Player.prototype.isTextTrackVisible = function() {
  return this.textTrack_.mode == 'showing';
};


/**
 * Set the visibility of the current text track, if any.
 *
 * @param {boolean} on
 * @export
 */
shaka.Player.prototype.setTextTrackVisibility = function(on) {
  this.textTrack_.mode = on ? 'showing' : 'hidden';
  this.onTextTrackVisibility_();
};


/**
 * Return playback and adaptation stats.
 *
 * @return {shakaExtern.Stats}
 * @export
 */
shaka.Player.prototype.getStats = function() {
  this.updateStats_();

  var video = {};
  var audio = {};
  var videoInfo = this.video_ && this.video_.getVideoPlaybackQuality ?
      this.video_.getVideoPlaybackQuality() :
      {};
  if (this.streamingEngine_) {
    var activeStreams = this.streamingEngine_.getActiveStreams();
    video = activeStreams['video'] || {};
    audio = activeStreams['audio'] || {};
  }

  return {
    width: video.width || 0,
    height: video.height || 0,
    streamBandwidth: (video.bandwidth + audio.bandwidth) || 0,

    decodedFrames: Number(videoInfo.totalVideoFrames),
    droppedFrames: Number(videoInfo.droppedVideoFrames),
    estimatedBandwidth: this.config_.abr.manager.getBandwidthEstimate(),
    playTime: this.playTime_,
    bufferingTime: this.bufferingTime_,

    switchHistory: this.switchHistory_.slice(0)
  };
};


/**
 * Adds the given text track to the current Period.  Load() must resolve before
 * calling.  The current Period or the presentation must have a duration.  This
 * returns a Promise that will resolve when the track can be switched to and
 * will resolve with the track that was created.
 *
 * @param {string} uri
 * @param {string} language
 * @param {string} kind
 * @param {string} mime
 * @param {string=} opt_codec
 * @return {!Promise.<shakaExtern.Track>}
 * @export
 */
shaka.Player.prototype.addTextTrack = function(
    uri, language, kind, mime, opt_codec) {
  if (!this.streamingEngine_) {
    shaka.log.error(
        'Must call load() and wait for it to resolve before adding text ' +
        'tracks.');
    return Promise.reject();
  }

  // Get the Period duration.
  var period = this.streamingEngine_.getCurrentPeriod();
  /** @type {number} */
  var periodDuration;
  for (var i = 0; i < this.manifest_.periods.length; i++) {
    if (this.manifest_.periods[i] == period) {
      if (i == this.manifest_.periods.length - 1) {
        periodDuration = this.manifest_.presentationTimeline.getDuration() -
            period.startTime;
        if (periodDuration == Number.POSITIVE_INFINITY) {
          shaka.log.error(
              'The current Period or the presentation must have a duration ' +
              'to add external text tracks.');
          return Promise.reject();
        }
      } else {
        var nextPeriod = this.manifest_.periods[i + 1];
        periodDuration = nextPeriod.startTime - period.startTime;
      }
      break;
    }
  }

  /** @type {shakaExtern.Stream} */
  var stream = {
    id: this.nextExternalStreamId_++,
    createSegmentIndex: Promise.resolve.bind(Promise),
    findSegmentPosition: function(time) { return 1; },
    getSegmentReference: function(ref) {
      if (ref != 1) return null;
      return new shaka.media.SegmentReference(
          1, 0, periodDuration, function() { return [uri]; }, 0, null);
    },
    initSegmentReference: null,
    presentationTimeOffset: 0,
    mimeType: mime,
    codecs: opt_codec || '',
    bandwidth: 0,
    kind: kind,
    encrypted: false,
    keyId: null,
    language: language,
    allowedByApplication: true,
    allowedByKeySystem: true
  };
  /** @type {shakaExtern.StreamSet} */
  var streamSet = {
    language: language,
    type: 'text',
    primary: false,
    drmInfos: [],
    streams: [stream]
  };

  // Add the stream to the loading list to ensure it isn't switched to while it
  // is initializing.
  this.loadingTextStreamIds_.push(stream.id);
  period.streamSets.push(streamSet);

  return this.streamingEngine_.notifyNewStream('text', stream).then(function() {
    if (this.destroyed_) return;

    // Remove the stream from the loading list.
    this.loadingTextStreamIds_.splice(
        this.loadingTextStreamIds_.indexOf(stream.id), 1);

    shaka.log.debug('Choosing new streams after adding a text stream');
    this.chooseStreamsAndSwitch_(period);
    this.onTracksChanged_();

    return {
      id: stream.id,
      active: false,
      type: 'text',
      bandwidth: 0,
      language: language,
      kind: kind,
      width: null,
      height: null
    };
  }.bind(this));
};


/**
 * Set the maximum resolution that the platform's hardware can handle.
 * This will be called automatically by shaka.cast.CastReceiver to enforce
 * limitations of the Chromecast hardware.
 *
 * @param {number} width
 * @param {number} height
 * @export
 */
shaka.Player.prototype.setMaxHardwareResolution = function(width, height) {
  this.maxHwRes_.width = width;
  this.maxHwRes_.height = height;
};


/**
 * Initialize the Player.
 * @private
 */
shaka.Player.prototype.initialize_ = function() {
  // Start the (potentially slow) process of opening MediaSource now.
  this.mediaSourceOpen_ = this.createMediaSource();

  // If the video element has TextTracks, disable them.  If we see one that
  // was created by a previous instance of Shaka Player, reuse it.
  for (var i = 0; i < this.video_.textTracks.length; ++i) {
    var track = this.video_.textTracks[i];
    track.mode = 'disabled';

    if (track.label == shaka.Player.TextTrackLabel_) {
      this.textTrack_ = track;
    }
  }

  if (!this.textTrack_) {
    // As far as I can tell, there is no observable difference between setting
    // kind to 'subtitles' or 'captions' when creating the TextTrack object.
    // The individual text tracks from the manifest will still have their own
    // kinds which can be displayed in the app's UI.
    this.textTrack_ = this.video_.addTextTrack(
        'subtitles', shaka.Player.TextTrackLabel_);
  }
  this.textTrack_.mode = 'hidden';

  // TODO: test that in all cases, the built-in CC controls in the video element
  // are toggling our TextTrack.

  // Listen for video errors.
  this.eventManager_.listen(this.video_, 'error',
      this.onVideoError_.bind(this));
};


/**
 * Destroy members responsible for streaming.
 *
 * @return {!Promise}
 * @private
 */
shaka.Player.prototype.destroyStreaming_ = function() {
  if (this.eventManager_) {
    this.eventManager_.unlisten(this.mediaSource_, 'sourceopen');
  }

  if (this.video_) {
    this.video_.removeAttribute('src');
    this.video_.load();
  }

  var p = Promise.all([
    this.config_ ? this.config_.abr.manager.stop() : null,
    this.drmEngine_ ? this.drmEngine_.destroy() : null,
    this.mediaSourceEngine_ ? this.mediaSourceEngine_.destroy() : null,
    this.playhead_ ? this.playhead_.destroy() : null,
    this.streamingEngine_ ? this.streamingEngine_.destroy() : null,
    this.parser_ ? this.parser_.stop() : null
  ]);

  this.drmEngine_ = null;
  this.mediaSourceEngine_ = null;
  this.playhead_ = null;
  this.streamingEngine_ = null;
  this.parser_ = null;
  this.manifest_ = null;
  this.manifestUri_ = null;
  this.mediaSourceOpen_ = null;
  this.mediaSource_ = null;
  this.deferredSwitches_ = {};
  this.switchHistory_ = [];
  this.playTime_ = 0;
  this.bufferingTime_ = 0;

  return p;
};


/**
 * Reset the streaming system.
 * @return {!Promise}
 * @private
 */
shaka.Player.prototype.resetStreaming_ = function() {
  if (!this.parser_) {
    // Nothing is playing, so this is effectively a no-op.
    return Promise.resolve();
  }

  // Destroy the streaming system before we recreate everything.
  return this.destroyStreaming_().then(function() {
    if (this.destroyed_) return;

    // Force an exit from the buffering state.
    this.onBuffering_(false);

    // Start the (potentially slow) process of opening MediaSource now.
    this.mediaSourceOpen_ = this.createMediaSource();
  }.bind(this));
};


/**
 * @const {string}
 * @private
 */
shaka.Player.TextTrackLabel_ = 'Shaka Player TextTrack';


/**
 * @return {!Object}
 * @private
 */
shaka.Player.prototype.configOverrides_ = function() {
  return {
    '.drm.servers': '',
    '.drm.clearKeys': '',
    '.drm.advanced': {
      distinctiveIdentifierRequired: false,
      persistentStateRequired: false,
      videoRobustness: '',
      audioRobustness: '',
      serverCertificate: null
    }
  };
};


/**
 * @return {shakaExtern.PlayerConfiguration}
 * @private
 */
shaka.Player.prototype.defaultConfig_ = function() {
  return {
    drm: {
      retryParameters: shaka.net.NetworkingEngine.defaultRetryParameters(),
      // These will all be verified by special cases in mergeConfigObjects_():
      servers: {},    // key is arbitrary key system ID, value must be string
      clearKeys: {},  // key is arbitrary key system ID, value must be string
      advanced: {}    // key is arbitrary key system ID, value is a record type
    },
    manifest: {
      retryParameters: shaka.net.NetworkingEngine.defaultRetryParameters(),
      dash: {
        customScheme: new Function('node', ''),
        clockSyncUri: ''
      }
    },
    streaming: {
      retryParameters: shaka.net.NetworkingEngine.defaultRetryParameters(),
      rebufferingGoal: 2,
      bufferingGoal: 30,
      bufferBehind: 30
    },
    abr: {
      manager: this.defaultAbrManager_,
      enabled: true,
      defaultBandwidthEstimate:
          shaka.abr.EwmaBandwidthEstimator.DEFAULT_ESTIMATE
    },
    preferredAudioLanguage: '',
    preferredTextLanguage: '',
    restrictions: {
      minWidth: 0,
      maxWidth: Number.POSITIVE_INFINITY,
      minHeight: 0,
      maxHeight: Number.POSITIVE_INFINITY,
      minPixels: 0,
      maxPixels: Number.POSITIVE_INFINITY,
      minAudioBandwidth: 0,
      maxAudioBandwidth: Number.POSITIVE_INFINITY,
      minVideoBandwidth: 0,
      maxVideoBandwidth: Number.POSITIVE_INFINITY
    }
  };
};


/**
 * @param {shakaExtern.Period} period
 * @private
 */
shaka.Player.prototype.filterPeriod_ = function(period) {
  goog.asserts.assert(this.video_, 'Must not be destroyed');

  var activeStreams =
      this.streamingEngine_ ? this.streamingEngine_.getActiveStreams() : {};
  shaka.util.StreamUtils.filterPeriod(this.drmEngine_, activeStreams, period);

  // Check for playable streams before restrictions to give a different error
  // if we have restricted all the tracks rather than there being none.
  var hasPlayableStreamSets =
      period.streamSets.some(shaka.util.StreamUtils.hasPlayableStreams);

  var tracksChanged = shaka.util.StreamUtils.applyRestrictions(
      period, this.config_.restrictions, this.maxHwRes_);
  if (tracksChanged && !this.loadChain_)
    this.onTracksChanged_();

  var allStreamsRestricted =
      !period.streamSets.some(shaka.util.StreamUtils.hasPlayableStreams);
  if (!hasPlayableStreamSets) {
    this.onError_(new shaka.util.Error(
        shaka.util.Error.Category.MANIFEST,
        shaka.util.Error.Code.UNPLAYABLE_PERIOD));
  } else if (allStreamsRestricted) {
    this.onError_(new shaka.util.Error(
        shaka.util.Error.Category.MANIFEST,
        shaka.util.Error.Code.RESTRICTIONS_CANNOT_BE_MET));
  }
};


/**
 * Switches to the given streams, deferring switches if needed.
 * @param {!Object.<string, shakaExtern.Stream>} streamsByType
 * @param {boolean=} opt_clearBuffer
 * @private
 */
shaka.Player.prototype.deferredSwitch_ = function(
    streamsByType, opt_clearBuffer) {
  for (var type in streamsByType) {
    var stream = streamsByType[type];
    var clear = opt_clearBuffer || type == 'text';
    if (this.switchingPeriods_) {
      this.deferredSwitches_[type] = {stream: stream, clear: clear};
    } else {
      var opt_leaveInBuffer = clear ? 0 : undefined;
      this.streamingEngine_.switch(type, stream, opt_leaveInBuffer);
    }
  }
};


/** @private */
shaka.Player.prototype.updateStats_ = function() {
  // Only count while we're loaded.
  if (!this.manifest_)
    return;

  var now = Date.now() / 1000;
  if (this.buffering_)
    this.bufferingTime_ += (now - this.lastStatUpdateTimestamp_);
  else
    this.playTime_ += (now - this.lastStatUpdateTimestamp_);

  this.lastStatUpdateTimestamp_ = now;
};


/**
 * Callback from NetworkingEngine.
 *
 * @param {number} startTimeMs
 * @param {number} endTimeMs
 * @param {number} numBytes
 * @private
 */
shaka.Player.prototype.onSegmentDownloaded_ = function(
    startTimeMs, endTimeMs, numBytes) {
  this.config_.abr.manager.segmentDownloaded(startTimeMs, endTimeMs, numBytes);
};


/**
 * Callback from Playhead.
 *
 * @param {boolean} buffering
 * @private
 */
shaka.Player.prototype.onBuffering_ = function(buffering) {
  // Before setting |buffering_|, update the time spent in the previous state.
  this.updateStats_();
  this.buffering_ = buffering;

  var event = new shaka.util.FakeEvent('buffering', { 'buffering': buffering });
  this.dispatchEvent(event);
};


/**
 * Callback from Playhead.
 *
 * @private
 */
shaka.Player.prototype.onSeek_ = function() {
  if (this.streamingEngine_) {
    this.streamingEngine_.seeked();
  }
};


/**
 * Chooses streams from the given Period.
 *
 * @param {!shakaExtern.Period} period
 * @param {!Object.<string, shakaExtern.StreamSet>} streamSetsByType
 * @param {boolean=} opt_chooseAll If true, choose streams from all stream sets.
 * @return {!Object.<string, !shakaExtern.Stream>} A map of stream types to
 *   chosen streams.
 * @private
 */
shaka.Player.prototype.chooseStreams_ =
    function(period, streamSetsByType, opt_chooseAll) {
  goog.asserts.assert(this.config_, 'Must not be destroyed');

  var hasPlayableStreams = shaka.util.StreamUtils.hasPlayableStreams;

  // If there are no unrestricted streams, issue an error.
  var manifestIsPlayable =
      shaka.util.MapUtils.values(streamSetsByType).some(hasPlayableStreams);
  if (!manifestIsPlayable) {
    this.onError_(new shaka.util.Error(
        shaka.util.Error.Category.MANIFEST,
        shaka.util.Error.Code.RESTRICTIONS_CANNOT_BE_MET));
    return {};
  }

  // Which StreamSets need to have their chosen stream updated.
  var needsUpdate = {};

  if (opt_chooseAll) {
    // Choose new streams for all types.
    needsUpdate = streamSetsByType;
  } else {
    // Check if any of the active streams is no longer available
    // or is using the wrong language.
    var activeStreams = this.streamingEngine_.getActiveStreams();
    for (var type in activeStreams) {
      var stream = activeStreams[type];
      if (!stream.allowedByApplication ||
          !stream.allowedByKeySystem ||
          streamSetsByType[type].language != stream.language) {
        needsUpdate[type] = streamSetsByType[type];
      }
    }
  }

  if (!shaka.util.MapUtils.empty(needsUpdate)) {
    shaka.log.debug('Choosing new streams for', Object.keys(needsUpdate));
    var chosen = this.config_.abr.manager.chooseStreams(needsUpdate);
    if (!shaka.util.MapUtils.every(needsUpdate,
        function(type, set) { return !!chosen[type]; })) {
      // Not every type was chosen!  This should only happen when output
      // restrictions prevent playback of a certain type and there are no
      // usable streams for that type.
      this.onError_(new shaka.util.Error(
          shaka.util.Error.Category.MANIFEST,
          shaka.util.Error.Code.RESTRICTIONS_CANNOT_BE_MET));
      return {};
    }
    return chosen;
  } else {
    shaka.log.debug('No new streams need to be chosen.');
    return {};
  }
};


/**
 * Chooses streams from the given Period and switches to them.
 *
 * @param {!shakaExtern.Period} period
 * @private
 */
shaka.Player.prototype.chooseStreamsAndSwitch_ = function(period) {
  goog.asserts.assert(this.config_, 'Must not be destroyed');
  var languageMatches = { 'audio': false, 'text': false };
  var streamSetsByType = shaka.util.StreamUtils.chooseStreamSets(
      period, this.config_, languageMatches);
  var chosen = this.chooseStreams_(period, streamSetsByType);

  for (var type in chosen) {
    var stream = chosen[type];
    this.switchHistory_.push({
      timestamp: Date.now() / 1000,
      id: stream.id,
      type: type,
      fromAdaptation: true
    });
  }

  // TODO: are these cases where we should avoid clearBuffer at this point?
  this.deferredSwitch_(chosen, /* clearBuffer */ true);

  // Send an adaptation event so that the UI can show the new language/tracks.
  this.onAdaptation_();

  if (streamSetsByType['text']) {
    // If audio and text tracks have different languages, and the text track
    // matches the user's preference, then show the captions.
    if (streamSetsByType['audio'] &&
        languageMatches['text'] &&
        streamSetsByType['text'].language !=
            streamSetsByType['audio'].language) {
      this.textTrack_.mode = 'showing';
      this.onTextTrackVisibility_();
    }
  }
};


/**
 * Callback from StreamingEngine.
 *
 * @param {!shakaExtern.Period} period
 * @return {!Object.<string, !shakaExtern.Stream>} A map of stream types to
 *   chosen streams.
 * @private
 */
shaka.Player.prototype.onChooseStreams_ = function(period) {
  shaka.log.debug('onChooseStreams_', period);
  goog.asserts.assert(this.config_, 'Must not be destroyed');

  // We are switching Periods, so the AbrManager will be disabled.  But if we
  // want to abr.enabled, we do not want to call AbrManager.enable before
  // canSwitch_ is called.
  this.switchingPeriods_ = true;
  this.config_.abr.manager.disable();

  shaka.log.debug('Choosing new streams after period changed');
  var streamSetsByType = shaka.util.StreamUtils.chooseStreamSets(
      period, this.config_);
  shaka.log.v2('onChooseStreams_, streamSetsByType=', streamSetsByType);
  var chosen = this.chooseStreams_(
      period, streamSetsByType, /* opt_chooseAll */ true);
  shaka.log.v2('onChooseStreams_, chosen=', chosen);

  // Override the chosen streams with the ones picked in selectTrack.
  // NOTE: The apparent race between selectTrack and period transition is
  // handled by StreamingEngine, which will re-request tracks for the
  // transition if any of these deferred selections are from the wrong period.
  for (var type in this.deferredSwitches_) {
    // We are choosing initial tracks, so no segments from this Period have
    // been downloaded yet.
    chosen[type] = this.deferredSwitches_[type].stream;
  }
  this.deferredSwitches_ = {};

  for (var type in chosen) {
    var stream = chosen[type];
    this.switchHistory_.push({
      timestamp: Date.now() / 1000,
      id: stream.id,
      type: type,
      fromAdaptation: true
    });
  }

  // If we are presently loading, we aren't done filtering streams just yet.
  // Wait to send a 'trackschanged' event.
  if (!this.loadChain_) {
    this.onTracksChanged_();
  }

  return chosen;
};


/**
 * Callback from StreamingEngine.
 *
 * @private
 */
shaka.Player.prototype.canSwitch_ = function() {
  shaka.log.debug('canSwitch_');
  this.switchingPeriods_ = false;
  if (this.config_.abr.enabled)
    this.config_.abr.manager.enable();

  // If we still have deferred switches, switch now.
  for (var type in this.deferredSwitches_) {
    var info = this.deferredSwitches_[type];
    var opt_leaveInBuffer = info.clear ? 0 : undefined;
    this.streamingEngine_.switch(type, info.stream, opt_leaveInBuffer);
  }
  this.deferredSwitches_ = {};
};


/**
 * Callback from AbrManager.
 *
 * @param {!Object.<string, !shakaExtern.Stream>} streamsByType
 * @param {number=} opt_leaveInBuffer
 * @private
 */
shaka.Player.prototype.switch_ = function(streamsByType, opt_leaveInBuffer) {
  shaka.log.debug('switch_');
  goog.asserts.assert(this.config_.abr.enabled,
      'AbrManager should not call switch while disabled!');
  goog.asserts.assert(!this.switchingPeriods_,
      'AbrManager should not call switch while transitioning between Periods!');

  // We have adapted to a new stream, record it in the history.  Only add if
  // we are actually switching the stream.
  var oldActive = this.streamingEngine_.getActiveStreams();
  for (var type in streamsByType) {
    var stream = streamsByType[type];
    if (oldActive[type] != stream) {
      this.switchHistory_.push({
        timestamp: Date.now() / 1000,
        id: stream.id,
        type: type,
        fromAdaptation: true
      });
    } else {
      // If it's the same, remove it from the map.
      // This allows us to avoid onAdaptation_() when nothing has changed.
      delete streamsByType[type];
    }
  }

  if (shaka.util.MapUtils.empty(streamsByType)) {
    // There's nothing to change.
    return;
  }

  if (!this.streamingEngine_) {
    // There's no way to change it.
    return;
  }

  for (var type in streamsByType) {
    this.streamingEngine_.switch(type, streamsByType[type],
        // Only apply opt_leaveInBuffer to video streams.
        type == 'video' ? opt_leaveInBuffer : undefined);
  }
  this.onAdaptation_();
};


/**
 * Dispatches a 'adaptation' event.
 * @private
 */
shaka.Player.prototype.onAdaptation_ = function() {
  // In the next frame, dispatch a 'adaptation' event.
  // This gives StreamingEngine time to absorb the changes before the user
  // tries to query them.
  Promise.resolve().then(function() {
    if (this.destroyed_) return;
    var event = new shaka.util.FakeEvent('adaptation');
    this.dispatchEvent(event);
  }.bind(this));
};


/**
 * Dispatches a 'trackschanged' event.
 * @private
 */
shaka.Player.prototype.onTracksChanged_ = function() {
  // In the next frame, dispatch a 'trackschanged' event.
  // This gives StreamingEngine time to absorb the changes before the user
  // tries to query them.
  Promise.resolve().then(function() {
    if (this.destroyed_) return;
    var event = new shaka.util.FakeEvent('trackschanged');
    this.dispatchEvent(event);
  }.bind(this));
};


/** @private */
shaka.Player.prototype.onTextTrackVisibility_ = function() {
  var event = new shaka.util.FakeEvent('texttrackvisibility');
  this.dispatchEvent(event);
};


/**
 * @param {!shaka.util.Error} error
 * @private
 */
shaka.Player.prototype.onError_ = function(error) {
  goog.asserts.assert(error instanceof shaka.util.Error, 'Wrong error type!');

  var event = new shaka.util.FakeEvent('error', { 'detail': error });
  this.dispatchEvent(event);
};


/**
 * @param {!Event} event
 * @private
 */
shaka.Player.prototype.onVideoError_ = function(event) {
  if (!this.video_.error) return;

  var code = this.video_.error.code;
  if (code == 1 /* MEDIA_ERR_ABORTED */) {
    // Ignore this error code, which should only occur when navigating away or
    // deliberately stopping playback of HTTP content.
    return;
  }

  // Extra error information from MS Edge and IE11:
  var extended = this.video_.error.msExtendedCode;
  if (extended) {
    // Convert to unsigned:
    if (extended < 0) {
      extended += Math.pow(2, 32);
    }
    // Format as hex:
    extended = extended.toString(16);
  }

  this.onError_(new shaka.util.Error(
      shaka.util.Error.Category.MEDIA,
      shaka.util.Error.Code.VIDEO_ERROR,
      code, extended));
};


/**
 * @param {!Object.<string, string>} keyStatusMap A map of hex key IDs to
 *   statuses.
 * @private
 */
shaka.Player.prototype.onKeyStatus_ = function(keyStatusMap) {
  goog.asserts.assert(this.streamingEngine_, 'Should have been initialized.');
  // NOTE: 'expired' is in the list of allowed statuses because expiration is
  // treated as a different condition than tracks being restricted.  It is not
  // expected that these keys are usable.
  var allowedStatuses =
      ['usable', 'status-pending', 'output-downscaled', 'expired'];

  var period = this.streamingEngine_.getCurrentPeriod();
  var tracksChanged = false;

  period.streamSets.forEach(function(streamSet) {
    streamSet.streams.forEach(function(stream) {
      var originalAllowed = stream.allowedByKeySystem;

      // Only update the status if it is in the map.
      if (stream.keyId && stream.keyId in keyStatusMap) {
        var keyStatus = keyStatusMap[stream.keyId];
        stream.allowedByKeySystem = allowedStatuses.indexOf(keyStatus) >= 0;
      }

      if (originalAllowed != stream.allowedByKeySystem) {
        tracksChanged = true;
      }
    });
  });

  shaka.log.debug('Choosing new streams after key status changed');
  this.chooseStreamsAndSwitch_(period);

  if (tracksChanged)
    this.onTracksChanged_();
};