player.js

/*! @license
 * Shaka Player
 * Copyright 2016 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

goog.provide('shaka.Player');

goog.require('goog.asserts');
goog.require('shaka.config.AutoShowText');
goog.require('shaka.Deprecate');
goog.require('shaka.log');
goog.require('shaka.media.AdaptationSetCriteria');
goog.require('shaka.media.BufferingObserver');
goog.require('shaka.media.DrmEngine');
goog.require('shaka.media.ExampleBasedCriteria');
goog.require('shaka.media.ManifestFilterer');
goog.require('shaka.media.ManifestParser');
goog.require('shaka.media.MediaSourceEngine');
goog.require('shaka.media.MediaSourcePlayhead');
goog.require('shaka.media.MetaSegmentIndex');
goog.require('shaka.media.PlayRateController');
goog.require('shaka.media.Playhead');
goog.require('shaka.media.PlayheadObserverManager');
goog.require('shaka.media.PreferenceBasedCriteria');
goog.require('shaka.media.PreloadManager');
goog.require('shaka.media.QualityObserver');
goog.require('shaka.media.RegionObserver');
goog.require('shaka.media.RegionTimeline');
goog.require('shaka.media.SegmentIndex');
goog.require('shaka.media.SegmentPrefetch');
goog.require('shaka.media.SegmentReference');
goog.require('shaka.media.SrcEqualsPlayhead');
goog.require('shaka.media.StreamingEngine');
goog.require('shaka.media.TimeRangesUtils');
goog.require('shaka.net.NetworkingEngine');
goog.require('shaka.net.NetworkingUtils');
goog.require('shaka.text.SimpleTextDisplayer');
goog.require('shaka.text.StubTextDisplayer');
goog.require('shaka.text.TextEngine');
goog.require('shaka.text.UITextDisplayer');
goog.require('shaka.text.WebVttGenerator');
goog.require('shaka.util.BufferUtils');
goog.require('shaka.util.CmcdManager');
goog.require('shaka.util.CmsdManager');
goog.require('shaka.util.ConfigUtils');
goog.require('shaka.util.Dom');
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.LanguageUtils');
goog.require('shaka.util.ManifestParserUtils');
goog.require('shaka.util.MediaReadyState');
goog.require('shaka.util.MimeUtils');
goog.require('shaka.util.Mutex');
goog.require('shaka.util.ObjectUtils');
goog.require('shaka.util.Platform');
goog.require('shaka.util.PlayerConfiguration');
goog.require('shaka.util.PublicPromise');
goog.require('shaka.util.Stats');
goog.require('shaka.util.StreamUtils');
goog.require('shaka.util.Timer');
goog.require('shaka.lcevc.Dec');
goog.requireType('shaka.media.PresentationTimeline');


/**
 * @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
 *   <code>category</code> and <code>code</code> properties will identify the
 *   specific error that occurred.  In an uncompiled build, you can also use the
 *   <code>message</code> and <code>stack</code> properties to debug.
 * @exportDoc
 */

/**
 * @event shaka.Player.StateChangeEvent
 * @description Fired when the player changes load states.
 * @property {string} type
 *    'onstatechange'
 * @property {string} state
 *    The name of the state that the player just entered.
 * @exportDoc
 */

/**
 * @event shaka.Player.EmsgEvent
 * @description Fired when an emsg box is found in a segment.
 *   If the application calls preventDefault() on this event, further parsing
 *   will not happen, and no 'metadata' event will be raised for ID3 payloads.
 * @property {string} type
 *   'emsg'
 * @property {shaka.extern.EmsgInfo} detail
 *   An object which contains the content of the emsg box.
 * @exportDoc
 */


/**
 * @event shaka.Player.DownloadFailed
 * @description Fired when a download has failed, for any reason.
 *   'downloadfailed'
 * @property {!shaka.extern.Request} request
 * @property {?shaka.util.Error} error
 * @param {number} httpResponseCode
 * @param {boolean} aborted
 * @exportDoc
 */


/**
 * @event shaka.Player.DownloadHeadersReceived
 * @description Fired when the networking engine has received the headers for
 *    a download, but before the body has been downloaded.
 *    If the HTTP plugin being used does not track this information, this event
 *    will default to being fired when the body is received, instead.
 * @property {!Object.<string, string>} headers
 * @property {!shaka.extern.Request} request
 * @property {!shaka.net.NetworkingEngine.RequestType} type
 *   'downloadheadersreceived'
 * @exportDoc
 */


/**
 * @event shaka.Player.DrmSessionUpdateEvent
 * @description Fired when the CDM has accepted the license response.
 * @property {string} type
 *   'drmsessionupdate'
 * @exportDoc
 */


/**
 * @event shaka.Player.TimelineRegionAddedEvent
 * @description Fired when a media timeline region is added.
 * @property {string} type
 *   'timelineregionadded'
 * @property {shaka.extern.TimelineRegionInfo} detail
 *   An object which contains a description of the region.
 * @exportDoc
 */


/**
 * @event shaka.Player.TimelineRegionEnterEvent
 * @description Fired when the playhead enters a timeline region.
 * @property {string} type
 *   'timelineregionenter'
 * @property {shaka.extern.TimelineRegionInfo} detail
 *   An object which contains a description of the region.
 * @exportDoc
 */


/**
 * @event shaka.Player.TimelineRegionExitEvent
 * @description Fired when the playhead exits a timeline region.
 * @property {string} type
 *   'timelineregionexit'
 * @property {shaka.extern.TimelineRegionInfo} detail
 *   An object which contains a description of the region.
 * @exportDoc
 */

/**
 * @event shaka.Player.MediaQualityChangedEvent
 * @description Fired when the media quality changes at the playhead.
 * That may be caused by an adaptation change or a DASH period transition.
 * Separate events are emitted for audio and video contentTypes.
 * This is supported for only DASH streams at this time.
 * @property {string} type
 *   'mediaqualitychanged'
 * @property {shaka.extern.MediaQualityInfo} mediaQuality
 *   Information about media quality at the playhead position.
 * @property {number} position
 *   The playhead position.
 * @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. The start of loading is
 *   defined as when the user has communicated intent to load content (i.e.
 *   <code>Player.load</code> has been called).
 * @property {string} type
 *   'loading'
 * @exportDoc
 */


/**
 * @event shaka.Player.LoadedEvent
 * @description Fired when the player ends the load.
 * @property {string} type
 *   'loaded'
 * @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 new tracks are added/removed 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
 *   <code>selectVariantTrack()</code>, <code>selectTextTrack()</code>,
 *   <code>selectAudioLanguage()</code>, or <code>selectTextLanguage()</code>.
 * @property {string} type
 *   'adaptation'
 * @property {shaka.extern.Track} oldTrack
 * @property {shaka.extern.Track} newTrack
 * @exportDoc
 */


/**
 * @event shaka.Player.VariantChangedEvent
 * @description Fired when a call from the application caused a variant change.
 *  Can be triggered by calls to <code>selectVariantTrack()</code> or
 *  <code>selectAudioLanguage()</code>. Does not fire when an automatic
 *  adaptation causes a variant change.
 * @property {string} type
 *   'variantchanged'
 * @property {shaka.extern.Track} oldTrack
 * @property {shaka.extern.Track} newTrack
 * @exportDoc
 */


/**
 * @event shaka.Player.TextChangedEvent
 * @description Fired when a call from the application caused a text stream
 *  change. Can be triggered by calls to <code>selectTextTrack()</code> or
 *  <code>selectTextLanguage()</code>.
 * @property {string} type
 *   'textchanged'
 * @exportDoc
 */


/**
 * @event shaka.Player.ExpirationUpdatedEvent
 * @description Fired when there is a change in the expiration times of an
 *   EME session.
 * @property {string} type
 *   'expirationupdated'
 * @exportDoc
 */


/**
 * @event shaka.Player.ManifestParsedEvent
 * @description Fired after the manifest has been parsed, but before anything
 *   else happens. The manifest may contain streams that will be filtered out,
 *   at this stage of the loading process.
 * @property {string} type
 *   'manifestparsed'
 * @exportDoc
 */


/**
 * @event shaka.Player.ManifestUpdatedEvent
 * @description Fired after the manifest has been updated (live streams).
 * @property {string} type
 *   'manifestupdated'
 * @property {boolean} isLive
 *   True when the playlist is live. Useful to detect transition from live
 *   to static playlist..
 * @exportDoc
 */


/**
 * @event shaka.Player.MetadataEvent
 * @description Triggers after metadata associated with the stream is found.
 *   Usually they are metadata of type ID3.
 * @property {string} type
 *   'metadata'
 * @property {number} startTime
 *   The time that describes the beginning of the range of the metadata to
 *   which the cue applies.
 * @property {?number} endTime
 *   The time that describes the end of the range of the metadata to which
 *   the cue applies.
 * @property {string} metadataType
 *   Type of metadata. Eg: org.id3 or org.mp4ra
 * @property {shaka.extern.MetadataFrame} payload
 *   The metadata itself
 * @exportDoc
 */


/**
 * @event shaka.Player.StreamingEvent
 * @description Fired after the manifest has been parsed and track information
 *   is available, but before streams have been chosen and before any segments
 *   have been fetched.  You may use this event to configure the player based on
 *   information found in the manifest.
 * @property {string} type
 *   'streaming'
 * @exportDoc
 */


/**
 * @event shaka.Player.AbrStatusChangedEvent
 * @description Fired when the state of abr has been changed.
 *    (Enabled or disabled).
 * @property {string} type
 *   'abrstatuschanged'
 * @property {boolean} newStatus
 *  The new status of the application. True for 'is enabled' and
 *  false otherwise.
 * @exportDoc
 */


/**
 * @event shaka.Player.RateChangeEvent
 * @description Fired when the video's playback rate changes.
 *    This allows the PlayRateController to update it's internal rate field,
 *    before the UI updates playback button with the newest playback rate.
 * @property {string} type
 *    'ratechange'
 * @exportDoc
 */


/**
 * @event shaka.Player.SegmentAppended
 * @description Fired when a segment is appended to the media element.
 * @property {string} type
 *   'segmentappended'
 * @property {number} start
 *   The start time of the segment.
 * @property {number} end
 *   The end time of the segment.
 * @property {string} contentType
 *   The content type of the segment. E.g. 'video', 'audio', or 'text'.
 * @exportDoc
 */


/**
 * @event shaka.Player.SessionDataEvent
 * @description Fired when the manifest parser find info about session data.
 *    Specification: https://tools.ietf.org/html/rfc8216#section-4.3.4.4
 * @property {string} type
 *   'sessiondata'
 * @property {string} id
 *   The id of the session data.
 * @property {string} uri
 *   The uri with the session data info.
 * @property {string} language
 *   The language of the session data.
 * @property {string} value
 *   The value of the session data.
 * @exportDoc
 */


/**
 * @event shaka.Player.StallDetectedEvent
 * @description Fired when a stall in playback is detected by the StallDetector.
 *     Not all stalls are caused by gaps in the buffered ranges.
 * @property {string} type
 *   'stalldetected'
 * @exportDoc
 */


/**
 * @event shaka.Player.GapJumpedEvent
 * @description Fired when the GapJumpingController jumps over a gap in the
 *     buffered ranges.
 * @property {string} type
 *   'gapjumped'
 * @exportDoc
 */


/**
 * @event shaka.Player.KeyStatusChanged
 * @description Fired when the key status changed.
 * @property {string} type
 *   'keystatuschanged'
 * @exportDoc
 */


/**
 * @event shaka.Player.StateChanged
 * @description Fired when player state is changed.
 * @property {string} type
 *   'statechanged'
 * @property {string} newstate
 *   The new state.
 * @exportDoc
 */


/**
 * @event shaka.Player.Started
 * @description Fires when the content starts playing.
 *     Only for VoD.
 * @property {string} type
 *   'started'
 * @exportDoc
 */


/**
 * @event shaka.Player.FirstQuartile
 * @description Fires when the content playhead crosses first quartile.
 *     Only for VoD.
 * @property {string} type
 *   'firstquartile'
 * @exportDoc
 */


/**
 * @event shaka.Player.Midpoint
 * @description Fires when the content playhead crosses midpoint.
 *     Only for VoD.
 * @property {string} type
 *   'midpoint'
 * @exportDoc
 */


/**
 * @event shaka.Player.ThirdQuartile
 * @description Fires when the content playhead crosses third quartile.
 *     Only for VoD.
 * @property {string} type
 *   'thirdquartile'
 * @exportDoc
 */


/**
 * @event shaka.Player.Complete
 * @description Fires when the content completes playing.
 *     Only for VoD.
 * @property {string} type
 *   'complete'
 * @exportDoc
 */


/**
 * @event shaka.Player.SpatialVideoInfoEvent
 * @description Fired when the video has spatial video info. If a previous
 *   event was fired, this include the new info.
 * @property {string} type
 *   'spatialvideoinfo'
 * @property {shaka.extern.SpatialVideoInfo} detail
 *   An object which contains the content of the emsg box.
 * @exportDoc
 */


/**
 * @event shaka.Player.NoSpatialVideoInfoEvent
 * @description Fired when the video no longer has spatial video information.
 *   For it to be fired, the shaka.Player.SpatialVideoInfoEvent event must
 *   have been previously fired.
 * @property {string} type
 *   'nospatialvideoinfo'
 * @exportDoc
 */


/**
 * @summary The main player object for Shaka Player.
 *
 * @implements {shaka.util.IDestroyable}
 * @export
 */
shaka.Player = class extends shaka.util.FakeEventTarget {
  /**
   * @param {HTMLMediaElement=} mediaElement
   *    When provided, the player will attach to <code>mediaElement</code>,
   *    similar to calling <code>attach</code>. When not provided, the player
   *    will remain detached.
   * @param {function(shaka.Player)=} dependencyInjector Optional callback
   *   which is called to inject mocks into the Player.  Used for testing.
   */
  constructor(mediaElement, dependencyInjector) {
    super();

    /** @private {shaka.Player.LoadMode} */
    this.loadMode_ = shaka.Player.LoadMode.NOT_LOADED;

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

    /** @private {HTMLElement} */
    this.videoContainer_ = null;

    /**
     * Since we may not always have a text displayer created (e.g. before |load|
     * is called), we need to track what text visibility SHOULD be so that we
     * can ensure that when we create the text displayer. When we create our
     * text displayer, we will use this to show (or not show) text as per the
     * user's requests.
     *
     * @private {boolean}
     */
    this.isTextVisible_ = false;

    /**
     * For listeners scoped to the lifetime of the Player instance.
     * @private {shaka.util.EventManager}
     */
    this.globalEventManager_ = new shaka.util.EventManager();

    /**
     * For listeners scoped to the lifetime of the media element attachment.
     * @private {shaka.util.EventManager}
     */
    this.attachEventManager_ = new shaka.util.EventManager();

    /**
     * For listeners scoped to the lifetime of the loaded content.
     * @private {shaka.util.EventManager}
     */
    this.loadEventManager_ = new shaka.util.EventManager();

    /**
     * For listeners scoped to the lifetime of the loaded content.
     * @private {shaka.util.EventManager}
     */
    this.trickPlayEventManager_ = new shaka.util.EventManager();

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

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

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

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

    /**
     * Incremented whenever a top-level operation (load, attach, etc) is
     * performed.
     * Used to determine if a load operation has been interrupted.
     * @private {number}
     */
    this.operationId_ = 0;

    /** @private {!shaka.util.Mutex} */
    this.mutex_ = new shaka.util.Mutex();

    /**
     * The playhead observers are used to monitor the position of the playhead
     * and some other source of data (e.g. buffered content), and raise events.
     *
     * @private {shaka.media.PlayheadObserverManager}
     */
    this.playheadObservers_ = null;

    /**
     * This is our control over the playback rate of the media element. This
     * provides the missing functionality that we need to provide trick play,
     * for example a negative playback rate.
     *
     * @private {shaka.media.PlayRateController}
     */
    this.playRateController_ = null;

    /** @private {shaka.media.BufferingObserver} */
    this.bufferObserver_ = null;

    /** @private {shaka.media.RegionTimeline} */
    this.regionTimeline_ = null;

    /** @private {shaka.util.CmcdManager} */
    this.cmcdManager_ = null;

    /** @private {shaka.util.CmsdManager} */
    this.cmsdManager_ = null;

    // This is the canvas element that will be used for rendering LCEVC
    // enhanced frames.
    /** @private {?HTMLCanvasElement} */
    this.lcevcCanvas_ = null;

    // This is the LCEVC Decoder object to decode LCEVC.
    /** @private {?shaka.lcevc.Dec} */
    this.lcevcDec_ = null;

    /** @private {shaka.media.QualityObserver} */
    this.qualityObserver_ = null;

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

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

    /** @private {?shaka.extern.ManifestParser.Factory} */
    this.parserFactory_ = null;

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

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

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

    /** @private {?number} */
    this.startTime_ = null;

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

    /** @private {shaka.extern.AbrManager} */
    this.abrManager_ = null;

    /**
     * The factory that was used to create the abrManager_ instance.
     * @private {?shaka.extern.AbrManager.Factory}
     */
    this.abrManagerFactory_ = 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.<shaka.extern.Stream>} */
    this.externalSrcEqualsThumbnailsStreams_ = [];

    /** @private {number} */
    this.completionPercent_ = NaN;

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

    /**
     * The TextDisplayerFactory that was last used to make a text displayer.
     * Stored so that we can tell if a new type of text displayer is desired.
     * @private {?shaka.extern.TextDisplayer.Factory}
     */
    this.lastTextFactory_;

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

    /** @private {!shaka.media.ManifestFilterer} */
    this.manifestFilterer_ = new shaka.media.ManifestFilterer(
        this.config_, this.maxHwRes_, null);

    /** @private {shaka.util.Stats} */
    this.stats_ = null;

    /** @private {!shaka.media.AdaptationSetCriteria} */
    this.currentAdaptationSetCriteria_ =
        new shaka.media.PreferenceBasedCriteria(
            this.config_.preferredAudioLanguage,
            this.config_.preferredVariantRole,
            this.config_.preferredAudioChannelCount,
            this.config_.preferredVideoHdrLevel,
            this.config_.preferSpatialAudio,
            this.config_.preferredVideoLayout,
            this.config_.preferredAudioLabel,
            this.config_.preferredVideoLabel,
            this.config_.mediaSource.codecSwitchingStrategy,
            this.config_.manifest.dash.enableAudioGroups);

    /** @private {string} */
    this.currentTextLanguage_ = this.config_.preferredTextLanguage;

    /** @private {string} */
    this.currentTextRole_ = this.config_.preferredTextRole;

    /** @private {boolean} */
    this.currentTextForced_ = this.config_.preferForcedSubs;

    /** @private {!Array.<function():(!Promise|undefined)>} */
    this.cleanupOnUnload_ = [];

    if (dependencyInjector) {
      dependencyInjector(this);
    }


    // Create the CMCD manager so client data can be attached to all requests
    this.cmcdManager_ = this.createCmcd_();

    this.cmsdManager_ = this.createCmsd_();

    this.networkingEngine_ = this.createNetworkingEngine();
    this.networkingEngine_.setForceHTTPS(this.config_.streaming.forceHTTPS);

    /** @private {shaka.extern.IAdManager} */
    this.adManager_ = null;

    if (shaka.Player.adManagerFactory_) {
      this.adManager_ = shaka.Player.adManagerFactory_();
      this.adManager_.configure(this.config_.ads);
    }

    // If the browser comes back online after being offline, then try to play
    // again.
    this.globalEventManager_.listen(window, 'online', () => {
      this.restoreDisabledVariants_();
      this.retryStreaming();
    });

    /** @private {shaka.util.Timer} */
    this.checkVariantsTimer_ =
        new shaka.util.Timer(() => this.checkVariants_());

    // Even though |attach| will start in later interpreter cycles, it should be
    // the LAST thing we do in the constructor because conceptually it relies on
    // player having been initialized.
    if (mediaElement) {
      shaka.Deprecate.deprecateFeature(5,
          'Player w/ mediaElement',
          'Please migrate from initializing Player with a mediaElement; ' +
          'use the attach method instead.');
      this.attach(mediaElement, /* initializeMediaSource= */ true);
    }
  }

  /**
   * Create a shaka.lcevc.Dec object
   * @param {shaka.extern.LcevcConfiguration} config
   * @private
   */
  createLcevcDec_(config) {
    if (this.lcevcDec_ == null) {
      this.lcevcDec_ = new shaka.lcevc.Dec(
          /** @type {HTMLVideoElement} */ (this.video_),
          this.lcevcCanvas_,
          config,
      );
      if (this.mediaSourceEngine_) {
        this.mediaSourceEngine_.updateLcevcDec(this.lcevcDec_);
      }
    }
  }

  /**
   * Close a shaka.lcevc.Dec object if present and hide the canvas.
   * @private
   */
  closeLcevcDec_() {
    if (this.lcevcDec_ != null) {
      this.lcevcDec_.hideCanvas();
      this.lcevcDec_.release();
      this.lcevcDec_ = null;
    }
  }

  /**
   * Setup shaka.lcevc.Dec object
   * @param {?shaka.extern.PlayerConfiguration} config
   * @private
   */
  setupLcevc_(config) {
    if (config.lcevc.enabled) {
      const tracks = this.getVariantTracks();
      if (tracks && tracks[0] && tracks[0].videoMimeType == 'video/mp2t') {
        const edge = shaka.util.Platform.isEdge() ||
          shaka.util.Platform.isLegacyEdge();
        if (edge) {
          if (!config.mediaSource.forceTransmux) {
            // If forceTransmux is disabled for Microsoft Edge, LCEVC data
            // is stripped out in case of a MPEG-2 TS container.
            // Hence the warning for Microsoft Edge when playing content with
            // MPEG-2 TS container.
            shaka.log.alwaysWarn('LCEVC Warning: For MPEG-2 TS decoding '+
            'the config.mediaSource.forceTransmux must be enabled.');
          }
        }
      }
      this.closeLcevcDec_();
      this.createLcevcDec_(config.lcevc);
    } else {
      this.closeLcevcDec_();
    }
  }

  /**
   * @param {!shaka.util.FakeEvent.EventName} name
   * @param {Map.<string, Object>=} data
   * @return {!shaka.util.FakeEvent}
   * @private
   */
  static makeEvent_(name, data) {
    return new shaka.util.FakeEvent(name, data);
  }

  /**
   * After destruction, a Player object cannot be used again.
   *
   * @override
   * @export
   */
  async destroy() {
    // Make sure we only execute the destroy logic once.
    if (this.loadMode_ == shaka.Player.LoadMode.DESTROYED) {
      return;
    }

    // If LCEVC Decoder exists close it.
    this.closeLcevcDec_();

    const detachPromise = this.detach();

    // Mark as "dead". This should stop external-facing calls from changing our
    // internal state any more. This will stop calls to |attach|, |detach|, etc.
    // from interrupting our final move to the detached state.
    this.loadMode_ = shaka.Player.LoadMode.DESTROYED;

    await detachPromise;

    // Tear-down the event managers to ensure handlers stop firing.
    if (this.globalEventManager_) {
      this.globalEventManager_.release();
      this.globalEventManager_ = null;
    }
    if (this.attachEventManager_) {
      this.attachEventManager_.release();
      this.attachEventManager_ = null;
    }
    if (this.loadEventManager_) {
      this.loadEventManager_.release();
      this.loadEventManager_ = null;
    }
    if (this.trickPlayEventManager_) {
      this.trickPlayEventManager_.release();
      this.trickPlayEventManager_ = null;
    }

    this.abrManagerFactory_ = null;
    this.config_ = null;
    this.stats_ = null;
    this.videoContainer_ = null;
    this.cmcdManager_ = null;
    this.cmsdManager_ = null;

    if (this.networkingEngine_) {
      await this.networkingEngine_.destroy();
      this.networkingEngine_ = null;
    }

    if (this.abrManager_) {
      this.abrManager_.release();
      this.abrManager_ = null;
    }

    // FakeEventTarget implements IReleasable
    super.release();
  }

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

  /**
   * Set a factory to create an ad manager during player construction time.
   * This method needs to be called bafore instantiating the Player class.
   *
   * @param {!shaka.extern.IAdManager.Factory} factory
   * @export
   */
  static setAdManagerFactory(factory) {
    shaka.Player.adManagerFactory_ = factory;
  }

  /**
   * 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
   */
  static isBrowserSupported() {
    if (!window.Promise) {
      shaka.log.alwaysWarn('A Promise implementation or polyfill is required');
    }

    // Basic features needed for the library to be usable.
    const basicSupport = !!window.Promise && !!window.Uint8Array &&
                         // eslint-disable-next-line no-restricted-syntax
                         !!Array.prototype.forEach;
    if (!basicSupport) {
      return false;
    }

    // We do not support IE
    if (shaka.util.Platform.isIE()) {
      return false;
    }

    const safariVersion = shaka.util.Platform.safariVersion();
    if (safariVersion && safariVersion < 9) {
      return false;
    }

    // DRM support is not strictly necessary, but the APIs at least need to be
    // there.  Our no-op DRM polyfill should handle that.
    // TODO(#1017): Consider making even DrmEngine optional.
    const drmSupport = shaka.media.DrmEngine.isBrowserSupported();
    if (!drmSupport) {
      return false;
    }

    // If we have MediaSource (MSE) support, we should be able to use Shaka.
    if (shaka.util.Platform.supportsMediaSource()) {
      return true;
    }

    // If we don't have MSE, we _may_ be able to use Shaka.  Look for native HLS
    // support, and call this platform usable if we have it.
    return shaka.util.Platform.supportsMediaType('application/x-mpegurl');
  }

  /**
   * 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.
   *
   * <p>
   * NOTE: This may show a request to the user for permission.
   *
   * @see https://bit.ly/2ywccmH
   * @param {boolean=} promptsOkay
   * @return {!Promise.<shaka.extern.SupportType>}
   * @export
   */
  static async probeSupport(promptsOkay=true) {
    goog.asserts.assert(shaka.Player.isBrowserSupported(),
        'Must have basic support');
    let drm = {};
    if (promptsOkay) {
      drm = await shaka.media.DrmEngine.probeSupport();
    }
    const manifest = shaka.media.ManifestParser.probeSupport();
    const media = shaka.media.MediaSourceEngine.probeSupport();
    const ret = {
      manifest: manifest,
      media: media,
      drm: drm,
    };

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

    return ret;
  }

  /**
   * Makes a fires an event corresponding to entering a state of the loading
   * process.
   * @param {string} nodeName
   * @private
   */
  makeStateChangeEvent_(nodeName) {
    this.dispatchEvent(shaka.Player.makeEvent_(
        /* name= */ shaka.util.FakeEvent.EventName.OnStateChange,
        /* data= */ (new Map()).set('state', nodeName)));
  }

  /**
   * Attaches the player to a media element.
   * If the player was already attached to a media element, first detaches from
   * that media element.
   *
   * @param {!HTMLMediaElement} mediaElement
   * @param {boolean=} initializeMediaSource
   * @return {!Promise}
   * @export
   */
  async attach(mediaElement, initializeMediaSource = true) {
    // Do not allow the player to be used after |destroy| is called.
    if (this.loadMode_ == shaka.Player.LoadMode.DESTROYED) {
      throw this.createAbortLoadError_();
    }

    const noop = this.video_ && this.video_ == mediaElement;

    if (this.video_ && this.video_ != mediaElement) {
      await this.detach();
    }

    if (await this.atomicOperationAcquireMutex_('attach')) {
      return;
    }

    try {
      if (!noop) {
        this.makeStateChangeEvent_('attach');

        const onError = (error) => this.onVideoError_(error);
        this.attachEventManager_.listen(mediaElement, 'error', onError);
        this.video_ = mediaElement;
      }

      // Only initialize media source if the platform supports it.
      if (initializeMediaSource &&
          shaka.util.Platform.supportsMediaSource() &&
          !this.mediaSourceEngine_) {
        await this.initializeMediaSourceEngineInner_();
      }
    } catch (error) {
      await this.detach();
      throw error;
    } finally {
      this.mutex_.release();
    }
  }


  /**
   * Calling <code>attachCanvas</code> will tell the player to set canvas
   * element for LCEVC decoding.
   *
   * @param {HTMLCanvasElement} canvas
   * @export
   */
  attachCanvas(canvas) {
    this.lcevcCanvas_ = canvas;
  }

  /**
   * Detach the player from the current media element. Leaves the player in a
   * state where it cannot play media, until it has been attached to something
   * else.
   *
   * @param {boolean=} keepAdManager
   *
   * @return {!Promise}
   * @export
   */
  async detach(keepAdManager = false) {
    // Do not allow the player to be used after |destroy| is called.
    if (this.loadMode_ == shaka.Player.LoadMode.DESTROYED) {
      throw this.createAbortLoadError_();
    }

    await this.unload(/* initializeMediaSource= */ false, keepAdManager);

    if (await this.atomicOperationAcquireMutex_('detach')) {
      return;
    }

    try {
      // If we were going from "detached" to "detached" we wouldn't have
      // a media element to detach from.
      if (this.video_) {
        this.attachEventManager_.removeAll();
        this.video_ = null;
      }

      this.makeStateChangeEvent_('detach');

      if (this.adManager_ && !keepAdManager) {
        // The ad manager is specific to the video, so detach it too.
        this.adManager_.release();
      }
    } finally {
      this.mutex_.release();
    }
  }

  /**
   * Tries to acquire the mutex, and then returns if the operation should end
   * early due to someone else starting a mutex-acquiring operation.
   * Meant for operations that can't be interrupted midway through (e.g.
   * everything but load).
   * @param {string} mutexIdentifier
   * @return {!Promise.<boolean>} endEarly If false, the calling context will
   *   need to release the mutex.
   * @private
   */
  async atomicOperationAcquireMutex_(mutexIdentifier) {
    const operationId = ++this.operationId_;
    await this.mutex_.acquire(mutexIdentifier);
    if (operationId != this.operationId_) {
      this.mutex_.release();
      return true;
    }
    return false;
  }

  /**
   * Unloads the currently playing stream, if any.
   *
   * @param {boolean=} initializeMediaSource
   * @param {boolean=} keepAdManager
   * @return {!Promise}
   * @export
   */
  async unload(initializeMediaSource = true, keepAdManager = false) {
    // Set the load mode to unload right away so that all the public methods
    // will stop using the internal components. We need to make sure that we
    // are not overriding the destroyed state because we will unload when we are
    // destroying the player.
    if (this.loadMode_ != shaka.Player.LoadMode.DESTROYED) {
      this.loadMode_ = shaka.Player.LoadMode.NOT_LOADED;
    }

    if (await this.atomicOperationAcquireMutex_('unload')) {
      return;
    }

    try {
      this.fullyLoaded_ = false;
      this.makeStateChangeEvent_('unload');

      // If the platform does not support media source, we will never want to
      // initialize media source.
      if (initializeMediaSource && !shaka.util.Platform.supportsMediaSource()) {
        initializeMediaSource = false;
      }

      // If LCEVC Decoder exists close it.
      this.closeLcevcDec_();

      // Run any general cleanup tasks now.  This should be here at the top,
      // right after setting loadMode_, so that internal components still exist
      // as they did when the cleanup tasks were registered in the array.
      const cleanupTasks = this.cleanupOnUnload_.map((cb) => cb());
      this.cleanupOnUnload_ = [];
      await Promise.all(cleanupTasks);

      // Dispatch the unloading event.
      this.dispatchEvent(
          shaka.Player.makeEvent_(shaka.util.FakeEvent.EventName.Unloading));

      // Release the region timeline, which is created when parsing the
      // manifest.
      if (this.regionTimeline_) {
        this.regionTimeline_.release();
        this.regionTimeline_ = null;
      }

      // In most cases we should have a media element. The one exception would
      // be if there was an error and we, by chance, did not have a media
      // element.
      if (this.video_) {
        this.loadEventManager_.removeAll();
        this.trickPlayEventManager_.removeAll();
      }

      // Stop the variant checker timer
      this.checkVariantsTimer_.stop();

      // Some observers use some playback components, shutting down the
      // observers first ensures that they don't try to use the playback
      // components mid-destroy.
      if (this.playheadObservers_) {
        this.playheadObservers_.release();
        this.playheadObservers_ = null;
      }

      // Stop the parser early. Since it is at the start of the pipeline, it
      // should be start early to avoid is pushing new data downstream.
      if (this.parser_) {
        await this.parser_.stop();
        this.parser_ = null;
        this.parserFactory_ = null;
      }

      // Abr Manager will tell streaming engine what to do, so we need to stop
      // it before we destroy streaming engine. Unlike with the other
      // components, we do not release the instance, we will reuse it in later
      // loads.
      if (this.abrManager_) {
        await this.abrManager_.stop();
      }

      // Streaming engine will push new data to media source engine, so we need
      // to shut it down before destroy media source engine.
      if (this.streamingEngine_) {
        await this.streamingEngine_.destroy();
        this.streamingEngine_ = null;
      }

      if (this.playRateController_) {
        this.playRateController_.release();
        this.playRateController_ = null;
      }

      // Playhead is used by StreamingEngine, so we can't destroy this until
      // after StreamingEngine has stopped.
      if (this.playhead_) {
        this.playhead_.release();
        this.playhead_ = null;
      }

      // Media source engine holds onto the media element, and in order to
      // detach the media keys (with drm engine), we need to break the
      // connection between media source engine and the media element.
      if (this.mediaSourceEngine_) {
        await this.mediaSourceEngine_.destroy();
        this.mediaSourceEngine_ = null;
      }

      if (this.adManager_ && !keepAdManager) {
        this.adManager_.onAssetUnload();
      }

      if (this.cmsdManager_) {
        this.cmsdManager_.reset();
      }

      if (this.video_) {
        // Remove all track nodes
        shaka.util.Dom.removeAllChildren(this.video_);
      }

      // In order to unload a media element, we need to remove the src attribute
      // and then load again. When we destroy media source engine, this will be
      // done for us, but for src=, we need to do it here.
      //
      // DrmEngine requires this to be done before we destroy DrmEngine itself.
      if (this.video_ && this.video_.src) {
        // TODO: Investigate this more.  Only reproduces on Firefox 69.
        // Introduce a delay before detaching the video source.  We are seeing
        // spurious Promise rejections involving an AbortError in our tests
        // otherwise.
        await new Promise(
            (resolve) => new shaka.util.Timer(resolve).tickAfter(0.1));

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

      if (this.drmEngine_) {
        await this.drmEngine_.destroy();
        this.drmEngine_ = null;
      }

      this.assetUri_ = null;
      this.mimeType_ = null;
      this.bufferObserver_ = null;

      if (this.manifest_) {
        for (const variant of this.manifest_.variants) {
          for (const stream of [variant.audio, variant.video]) {
            if (stream && stream.segmentIndex) {
              stream.segmentIndex.release();
            }
          }
        }
        for (const stream of this.manifest_.textStreams) {
          if (stream.segmentIndex) {
            stream.segmentIndex.release();
          }
        }
      }

      this.manifest_ = null;
      this.stats_ = new shaka.util.Stats(); // Replace with a clean object.
      this.lastTextFactory_ = null;

      this.externalSrcEqualsThumbnailsStreams_ = [];

      this.completionPercent_ = NaN;

      // Make sure that the app knows of the new buffering state.
      this.updateBufferState_();
    } finally {
      this.mutex_.release();
    }

    if (initializeMediaSource && shaka.util.Platform.supportsMediaSource() &&
        !this.mediaSourceEngine_) {
      await this.initializeMediaSourceEngineInner_();
    }
  }

  /**
   * Provides a way to update the stream start position during the media loading
   * process. Can for example be called from the <code>manifestparsed</code>
   * event handler to update the start position based on information in the
   * manifest.
   *
   * @param {number} startTime
   * @export
   */
  updateStartTime(startTime) {
    this.startTime_ = startTime;
  }

  /**
   * Loads a new stream.
   * If another stream was already playing, first unloads that stream.
   *
   * @param {string|shaka.media.PreloadManager} assetUriOrPreloader
   * @param {?number=} startTime
   *    When <code>startTime</code> is <code>null</code> or
   *    <code>undefined</code>, playback will start at the default start time (0
   *    for VOD and liveEdge for LIVE).
   * @param {?string=} mimeType
   * @return {!Promise}
   * @export
   */
  async load(assetUriOrPreloader, startTime = null, mimeType) {
    // Do not allow the player to be used after |destroy| is called.
    if (this.loadMode_ == shaka.Player.LoadMode.DESTROYED) {
      throw this.createAbortLoadError_();
    }

    /** @type {?shaka.media.PreloadManager} */
    let preloadManager = null;
    let assetUri = '';
    if (assetUriOrPreloader instanceof shaka.media.PreloadManager) {
      preloadManager = assetUriOrPreloader;
      assetUri = preloadManager.getAssetUri() || '';
    } else {
      assetUri = assetUriOrPreloader || '';
    }

    // Quickly acquire the mutex, so this will wait for other top-level
    // operations.
    await this.mutex_.acquire('load');
    this.mutex_.release();

    if (!this.video_) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.PLAYER,
          shaka.util.Error.Code.NO_VIDEO_ELEMENT);
    }

    if (this.assetUri_) {
      await this.unload(/* initializeMediaSource= */ false);
    }

    // Add a mechanism to detect if the load process has been interrupted by a
    // call to another top-level operation (unload, load, etc).
    const operationId = ++this.operationId_;
    const detectInterruption = async () => {
      if (this.operationId_ != operationId) {
        if (preloadManager) {
          await preloadManager.destroy();
        }
        throw this.createAbortLoadError_();
      }
    };

    /**
     * Wraps a given operation with mutex.acquire and mutex.release, along with
     * calls to detectInterruption, to catch any other top-level calls happening
     * while waiting for the mutex.
     * @param {function():!Promise} operation
     * @param {string} mutexIdentifier
     * @return {!Promise}
     */
    const mutexWrapOperation = async (operation, mutexIdentifier) => {
      try {
        await this.mutex_.acquire(mutexIdentifier);
        await detectInterruption();
        await operation();
        await detectInterruption();
        if (preloadManager && this.config_) {
          preloadManager.reconfigure(this.config_);
        }
      } finally {
        this.mutex_.release();
      }
    };

    try {
      if (startTime == null && preloadManager) {
        startTime = preloadManager.getStartTime();
      }
      this.startTime_ = startTime;
      this.fullyLoaded_ = false;

      // We dispatch the loading event when someone calls |load| because we want
      // to surface the user intent.
      this.dispatchEvent(shaka.Player.makeEvent_(
          shaka.util.FakeEvent.EventName.Loading));

      if (preloadManager) {
        mimeType = preloadManager.getMimeType();
      } else if (!mimeType) {
        await mutexWrapOperation(async () => {
          mimeType = await this.guessMimeType_(assetUri);
        }, 'guessMimeType_');
      }

      const wasPreloaded = !!preloadManager;
      if (!preloadManager) {
        // For simplicity, if an asset is NOT preloaded, start an internal
        // "preload" here without prefetch.
        // That way, both a preload and normal load can follow the same code
        // paths.
        // NOTE: await preloadInner_ can be outside the mutex because it should
        // not mutate "this".
        preloadManager = await this.preloadInner_(
            assetUri, startTime, mimeType, /* standardLoad= */ true);
        if (preloadManager) {
          preloadManager.setEventHandoffTarget(this);
          this.stats_ = preloadManager.getStats();
          await mutexWrapOperation(() => preloadManager.start(), 'preload');
        } else {
          this.stats_ = new shaka.util.Stats();
        }
      } else {
        // Hook up events, so any events emitted by the preloadManager will
        // instead be emitted by the player.
        preloadManager.setEventHandoffTarget(this);
        this.stats_ = preloadManager.getStats();
      }
      // Now, if there is no preload manager, that means that this is a src=
      // asset.
      const shouldUseSrcEquals = !preloadManager;

      const startTimeOfLoad = preloadManager ?
          preloadManager.getStartTimeOfLoad() : (Date.now() / 1000);

      // Stats are for a single playback/load session. Stats must be initialized
      // before we allow calls to |updateStateHistory|.
      this.stats_ =
          preloadManager ? preloadManager.getStats() : new shaka.util.Stats();

      this.assetUri_ = assetUri;
      this.mimeType_ = mimeType || null;

      if (shouldUseSrcEquals) {
        await mutexWrapOperation(async () => {
          goog.asserts.assert(mimeType, 'We should know the mimeType by now!');
          await this.initializeSrcEqualsDrmInner_(mimeType);
        }, 'initializeSrcEqualsDrmInner_');
        await mutexWrapOperation(async () => {
          goog.asserts.assert(mimeType, 'We should know the mimeType by now!');
          await this.srcEqualsInner_(startTimeOfLoad, mimeType);
        }, 'srcEqualsInner_');
      } else {
        if (!this.mediaSourceEngine_) {
          await mutexWrapOperation(async () => {
            await this.initializeMediaSourceEngineInner_();
          }, 'initializeMediaSourceEngineInner_');
        }

        // Get manifest and associated values from preloader.
        await mutexWrapOperation(
            () => preloadManager.waitForManifest(), 'waitForManifest');
        this.config_ = preloadManager.getConfiguration();
        this.manifestFilterer_ = preloadManager.getManifestFilterer();
        this.parserFactory_ = preloadManager.getParserFactory();
        this.parser_ = preloadManager.receiveParser();
        this.regionTimeline_ = preloadManager.receiveRegionTimeline();
        this.qualityObserver_ = preloadManager.getQualityObserver();
        this.manifest_ = preloadManager.getManifest();
        const currentAdaptationSetCriteria =
            preloadManager.getCurrentAdaptationSetCriteria();
        if (currentAdaptationSetCriteria) {
          this.currentAdaptationSetCriteria_ = currentAdaptationSetCriteria;
        }
        if (wasPreloaded && this.video_ && this.video_.nodeName === 'AUDIO') {
          // Filter the variants to be audio-only after the fact.
          // As, when preloading, we don't know if we are going to be attached
          // to a video or audio element when we load, we have to do the auto
          // audio-only filtering here, post-facto.
          this.makeManifestAudioOnly_();
          // And continue to do so in the future.
          this.configure('manifest.disableVideo', true);
        }

        // Get drm engine from preloader, then finalize it.
        await mutexWrapOperation(
            () => preloadManager.waitForDrm(), 'waitForDrm');
        this.drmEngine_ = preloadManager.receiveDrmEngine();
        await mutexWrapOperation(async () => {
          await this.drmEngine_.attach(this.video_);
        }, 'drmEngine_.attach');

        // Choose an initial variant.
        await mutexWrapOperation(
            () => preloadManager.waitForChooseInitialVariant(),
            'waitForChooseInitialVariant');

        // Also get the ABR manager, which has special logic related to being
        // received.
        const abrManagerFactory = preloadManager.getAbrManagerFactory();
        if (abrManagerFactory) {
          if (!this.abrManagerFactory_ ||
              this.abrManagerFactory_ != abrManagerFactory) {
            this.abrManager_ = preloadManager.receiveAbrManager();
            this.abrManagerFactory_ = preloadManager.getAbrManagerFactory();
            if (typeof this.abrManager_.setMediaElement != 'function') {
              shaka.Deprecate.deprecateFeature(5,
                  'AbrManager w/o setMediaElement',
                  'Please use an AbrManager with setMediaElement function.');
              this.abrManager_.setMediaElement = () => {};
            }
            if (typeof this.abrManager_.setCmsdManager != 'function') {
              shaka.Deprecate.deprecateFeature(5,
                  'AbrManager w/o setCmsdManager',
                  'Please use an AbrManager with setCmsdManager function.');
              this.abrManager_.setCmsdManager = () => {};
            }
            if (typeof this.abrManager_.trySuggestStreams != 'function') {
              shaka.Deprecate.deprecateFeature(5,
                  'AbrManager w/o trySuggestStreams',
                  'Please use an AbrManager with trySuggestStreams function.');
              this.abrManager_.trySuggestStreams = () => {};
            }
          }
        }

        // Load the asset.
        const segmentPrefetchById =
              preloadManager.receiveSegmentPrefetchesById();
        const prefetchedVariant = preloadManager.getPrefetchedVariant();
        await mutexWrapOperation(async () => {
          await this.loadInner_(
              startTimeOfLoad, prefetchedVariant, segmentPrefetchById);
        }, 'loadInner_');
        preloadManager.stopQueuingLatePhaseQueuedOperations();
      }
      this.dispatchEvent(shaka.Player.makeEvent_(
          shaka.util.FakeEvent.EventName.Loaded));
    } catch (error) {
      if (error.code != shaka.util.Error.Code.LOAD_INTERRUPTED) {
        await this.unload(/* initializeMediaSource= */ false);
      }
      throw error;
    } finally {
      if (preloadManager) {
        // This will cause any resources that were generated but not used to be
        // properly destroyed or released.
        await preloadManager.destroy();
      }
    }
  }

  /**
   * Modifies the current manifest so that it is audio-only.
   * @private
   */
  makeManifestAudioOnly_() {
    for (const variant of this.manifest_.variants) {
      if (variant.video) {
        variant.video.closeSegmentIndex();
        variant.video = null;
      }
      if (variant.audio && variant.audio.bandwidth) {
        variant.bandwidth = variant.audio.bandwidth;
      } else {
        variant.bandwidth = 0;
      }
    }
    this.manifest_.variants = this.manifest_.variants.filter((v) => {
      return v.audio;
    });
  }

  /**
   * Unloads the currently playing stream, if any, and returns a PreloadManager
   * that contains the loaded manifest of that asset, if any.
   * Allows for the asset to be re-loaded by this player faster, in the future.
   * When in src= mode, this unloads but does not make a PreloadManager.
   *
   * @param {boolean=} initializeMediaSource
   * @param {boolean=} keepAdManager
   * @return {!Promise.<?shaka.media.PreloadManager>}
   * @export
   */
  async unloadAndSavePreload(
      initializeMediaSource = true, keepAdManager = false) {
    let preloadManager = null;
    if (this.manifest_ && this.parser_ && this.parserFactory_ &&
        this.assetUri_) {
      let startTime = this.video_.currentTime;
      if (this.isLive()) {
        startTime = null;
      }
      // We have enough information to make a PreloadManager!
      const startTimeOfLoad = Date.now() / 1000;
      preloadManager = await this.makePreloadManager_(
          this.assetUri_,
          startTime,
          this.mimeType_,
          startTimeOfLoad,
          /* allowPrefetch= */ true,
          /* disableVideo= */ false,
          /* allowMakeAbrManager= */ false);
      preloadManager.attachManifest(
          this.manifest_, this.parser_, this.parserFactory_);
      preloadManager.attachAbrManager(
          this.abrManager_, this.abrManagerFactory_);
      preloadManager.attachAdaptationSetCriteria(
          this.currentAdaptationSetCriteria_);
      preloadManager.start();
      // Null the manifest and manifestParser, so that they won't be shut down
      // during unload and will continue to live inside the preloadManager.
      this.manifest_ = null;
      this.parser_ = null;
      this.parserFactory_ = null;
      // Null the abrManager and abrManagerFactory, so that they won't be shut
      // down during unload and will continue to live inside the preloadManager.
      this.abrManager_ = null;
      this.abrManagerFactory_ = null;
    }
    await this.unload(initializeMediaSource, keepAdManager);
    return preloadManager;
  }

  /**
   * Starts to preload a given asset, and returns a PreloadManager object that
   * represents that preloading process.
   * The PreloadManager will load the manifest for that asset, as well as the
   * initialization segment. It will not preload anything more than that;
   * this feature is intended for reducing start-time latency, not for fully
   * downloading assets before playing them (for that, use
   * |shaka.offline.Storage|).
   * You can pass that PreloadManager object in to the |load| method on this
   * Player instance to finish loading that particular asset, or you can call
   * the |destroy| method on the manager if the preload is no longer necessary.
   * If this returns null rather than a PreloadManager, that indicates that the
   * asset must be played with src=, which cannot be preloaded.
   *
   * @param {string} assetUri
   * @param {?number=} startTime
   *    When <code>startTime</code> is <code>null</code> or
   *    <code>undefined</code>, playback will start at the default start time (0
   *    for VOD and liveEdge for LIVE).
   * @param {?string=} mimeType
   * @return {!Promise.<?shaka.media.PreloadManager>}
   * @export
   */
  async preload(assetUri, startTime = null, mimeType) {
    const preloadManager = await this.preloadInner_(
        assetUri, startTime, mimeType);
    if (!preloadManager) {
      this.onError_(new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.PLAYER,
          shaka.util.Error.Code.SRC_EQUALS_PRELOAD_NOT_SUPPORTED));
    } else {
      preloadManager.start().catch((error) => {}); // Catch errors.
    }
    return preloadManager;
  }

  /**
   * @param {string} assetUri
   * @param {?number} startTime
   * @param {?string=} mimeType
   * @param {boolean=} standardLoad
   * @return {!Promise.<?shaka.media.PreloadManager>}
   * @private
   */
  async preloadInner_(assetUri, startTime, mimeType, standardLoad = false) {
    goog.asserts.assert(this.networkingEngine_, 'Should have a net engine!');
    goog.asserts.assert(this.config_, 'Config must not be null!');
    const startTimeOfLoad = Date.now() / 1000;
    if (!mimeType) {
      mimeType = await this.guessMimeType_(assetUri);
    }
    const shouldUseSrcEquals = this.shouldUseSrcEquals_(assetUri, mimeType);
    if (shouldUseSrcEquals) {
      // We cannot preload src= content.
      return null;
    }
    let disableVideo = false;
    let allowMakeAbrManager = true;
    if (standardLoad) {
      if (this.abrManager_ &&
          this.abrManagerFactory_ == this.config_.abrFactory) {
        // If there's already an abr manager, don't make a new abr manager at
        // all.
        // In standardLoad mode, the abr manager isn't used for anything anyway,
        // so it should only be created to create an abr manager for the player
        // to use... which is unnecessary if we already have one of the right
        // type.
        allowMakeAbrManager = false;
      }
      if (this.video_ && this.video_.nodeName === 'AUDIO') {
        disableVideo = true;
      }
    }
    return this.makePreloadManager_(
        assetUri, startTime, mimeType || null, startTimeOfLoad,
        /* allowPrefetch= */ !standardLoad, disableVideo, allowMakeAbrManager);
  }

  /**
   * @param {string} assetUri
   * @param {?number} startTime
   * @param {?string} mimeType
   * @param {number} startTimeOfLoad
   * @param {boolean=} allowPrefetch
   * @param {boolean=} disableVideo
   * @param {boolean=} allowMakeAbrManager
   * @return {!Promise.<!shaka.media.PreloadManager>}
   * @private
   */
  async makePreloadManager_(assetUri, startTime, mimeType, startTimeOfLoad,
      allowPrefetch = true, disableVideo = false, allowMakeAbrManager = true) {
    goog.asserts.assert(this.networkingEngine_, 'Must have net engine');
    /** @type {?shaka.media.PreloadManager} */
    let preloadManager = null;

    const config = shaka.util.ObjectUtils.cloneObject(this.config_);
    if (disableVideo) {
      config.manifest.disableVideo = true;
    }

    const getPreloadManager = () => {
      goog.asserts.assert(preloadManager, 'Must have preload manager');
      if (preloadManager.hasBeenAttached() && preloadManager.isDestroyed()) {
        return null;
      }
      return preloadManager;
    };

    const getConfig = () => {
      if (getPreloadManager()) {
        return getPreloadManager().getConfiguration();
      } else {
        return this.config_;
      }
    };

    const setConfig = (name, value) => {
      if (getPreloadManager()) {
        preloadManager.configure(name, value);
      } else {
        this.configure(name, value);
      }
    };

    // Avoid having to detect the resolution again if it has already been
    // detected or set
    if (this.maxHwRes_.width == Infinity &&
        this.maxHwRes_.height == Infinity) {
      const maxResolution =
          await shaka.util.Platform.detectMaxHardwareResolution();
      this.maxHwRes_.width = maxResolution.width;
      this.maxHwRes_.height = maxResolution.height;
    }
    const manifestFilterer = new shaka.media.ManifestFilterer(
        config, this.maxHwRes_, null);
    const manifestPlayerInterface = {
      networkingEngine: this.networkingEngine_,
      filter: async (manifest) => {
        const tracksChanged = await manifestFilterer.filterManifest(manifest);
        if (tracksChanged) {
          // Delay the 'trackschanged' event so StreamingEngine has time to
          // absorb the changes before the user tries to query it.
          const event = shaka.Player.makeEvent_(
              shaka.util.FakeEvent.EventName.TracksChanged);
          await Promise.resolve();
          preloadManager.dispatchEvent(event);
        }
      },
      makeTextStreamsForClosedCaptions: (manifest) => {
        return this.makeTextStreamsForClosedCaptions_(manifest);
      },

      // Called when the parser finds a timeline region. This can be called
      // before we start playback or during playback (live/in-progress
      // manifest).
      onTimelineRegionAdded: (region) => {
        preloadManager.getRegionTimeline().addRegion(region);
      },

      onEvent: (event) => preloadManager.dispatchEvent(event),
      onError: (error) => preloadManager.onError(error),
      isLowLatencyMode: () => getConfig().streaming.lowLatencyMode,
      isAutoLowLatencyMode: () => getConfig().streaming.autoLowLatencyMode,
      enableLowLatencyMode: () => {
        setConfig('streaming.lowLatencyMode', true);
      },
      updateDuration: () => {
        if (this.streamingEngine_ && preloadManager.hasBeenAttached()) {
          this.streamingEngine_.updateDuration();
        }
      },
      newDrmInfo: (stream) => {
        // We may need to create new sessions for any new init data.
        const drmEngine = preloadManager.getDrmEngine();
        const currentDrmInfo = drmEngine ? drmEngine.getDrmInfo() : null;
        // DrmEngine.newInitData() requires mediaKeys to be available.
        if (currentDrmInfo && drmEngine.getMediaKeys()) {
          manifestFilterer.processDrmInfos(currentDrmInfo.keySystem, stream);
        }
      },
      onManifestUpdated: () => {
        const eventName = shaka.util.FakeEvent.EventName.ManifestUpdated;
        const data = (new Map()).set('isLive', this.isLive());
        preloadManager.dispatchEvent(shaka.Player.makeEvent_(eventName, data));

        preloadManager.addQueuedOperation(false, () => {
          if (this.adManager_) {
            this.adManager_.onManifestUpdated(this.isLive());
          }
        });
      },
      getBandwidthEstimate: () => this.abrManager_.getBandwidthEstimate(),
    };
    const regionTimeline =
        new shaka.media.RegionTimeline(() => this.seekRange());
    regionTimeline.addEventListener('regionadd', (event) => {
      /** @type {shaka.extern.TimelineRegionInfo} */
      const region = event['region'];
      this.onRegionEvent_(
          shaka.util.FakeEvent.EventName.TimelineRegionAdded, region,
          preloadManager);

      preloadManager.addQueuedOperation(false, () => {
        if (this.adManager_) {
          this.adManager_.onDashTimedMetadata(region);
        }
      });
    });
    let qualityObserver = null;
    if (config.streaming.observeQualityChanges) {
      qualityObserver = new shaka.media.QualityObserver(
          () => this.getBufferedInfo());

      qualityObserver.addEventListener('qualitychange', (event) => {
        /** @type {shaka.extern.MediaQualityInfo} */
        const mediaQualityInfo = event['quality'];
        /** @type {number} */
        const position = event['position'];
        this.onMediaQualityChange_(mediaQualityInfo, position);
      });
    }
    let firstEvent = true;
    const drmPlayerInterface = {
      netEngine: this.networkingEngine_,
      onError: (e) => preloadManager.onError(e),
      onKeyStatus: (map) => {
        preloadManager.addQueuedOperation(true, () => {
          this.onKeyStatus_(map);
        });
      },
      onExpirationUpdated: (id, expiration) => {
        const event = shaka.Player.makeEvent_(
            shaka.util.FakeEvent.EventName.ExpirationUpdated);
        preloadManager.dispatchEvent(event);
        const parser = preloadManager.getParser();
        if (parser && parser.onExpirationUpdated) {
          parser.onExpirationUpdated(id, expiration);
        }
      },
      onEvent: (e) => {
        preloadManager.dispatchEvent(e);
        if (e.type == shaka.util.FakeEvent.EventName.DrmSessionUpdate &&
            firstEvent) {
          firstEvent = false;
          const now = Date.now() / 1000;
          const delta = now - preloadManager.getStartTimeOfDRM();
          const stats = this.stats_ || preloadManager.getStats();
          stats.setDrmTime(delta);
          // LCEVC data by itself is not encrypted in DRM protected streams
          // and can therefore be accessed and decoded as normal. However,
          // the LCEVC decoder needs access to the VideoElement output in
          // order to apply the enhancement. In DRM contexts where the
          // browser CDM restricts access from our decoder, the enhancement
          // cannot be applied and therefore the LCEVC output canvas is
          // hidden accordingly.
          if (this.lcevcDec_) {
            this.lcevcDec_.hideCanvas();
          }
        }
      },
    };

    // Sadly, as the network engine creation code must be replaceable by tests,
    // it cannot be made and use the utilities defined in this function.
    const networkingEngine = this.createNetworkingEngine(getPreloadManager);

    /** @return {!shaka.media.DrmEngine} */
    const createDrmEngine = () => {
      return this.createDrmEngine(drmPlayerInterface);
    };
    /** @type {!shaka.media.PreloadManager.PlayerInterface} */
    const playerInterface = {
      config,
      manifestPlayerInterface,
      regionTimeline,
      qualityObserver,
      createDrmEngine,
      manifestFilterer,
      networkingEngine,
      allowPrefetch,
      allowMakeAbrManager,
    };
    preloadManager = new shaka.media.PreloadManager(
        assetUri, mimeType, startTimeOfLoad, startTime, playerInterface);
    return preloadManager;
  }

  /**
   * Determines the mimeType of the given asset, if we are not told that inside
   * the loading process.
   *
   * @param {string} assetUri
   * @return {!Promise.<?string>} mimeType
   * @private
   */
  async guessMimeType_(assetUri) {
    // If no MIME type is provided, and we can't base it on extension, make a
    // HEAD request to determine it.
    goog.asserts.assert(this.networkingEngine_, 'Should have a net engine!');
    const retryParams = this.config_.manifest.retryParameters;
    let mimeType = await shaka.net.NetworkingUtils.getMimeType(
        assetUri, this.networkingEngine_, retryParams);
    if (mimeType == 'application/x-mpegurl' && shaka.util.Platform.isApple()) {
      mimeType = 'application/vnd.apple.mpegurl';
    }
    return mimeType;
  }

  /**
   * Determines if we should use src equals, based on the the mimeType (if
   * known), the URI, and platform information.
   *
   * @param {string} assetUri
   * @param {?string=} mimeType
   * @return {boolean}
   *    |true| if the content should be loaded with src=, |false| if the content
   *    should be loaded with MediaSource.
   * @private
   */
  shouldUseSrcEquals_(assetUri, mimeType) {
    const Platform = shaka.util.Platform;
    const MimeUtils = shaka.util.MimeUtils;

    // If we are using a platform that does not support media source, we will
    // fall back to src= to handle all playback.
    if (!Platform.supportsMediaSource()) {
      return true;
    }

    if (mimeType) {
      // If we have a MIME type, check if the browser can play it natively.
      // This will cover both single files and native HLS.
      const mediaElement = this.video_ || Platform.anyMediaElement();
      const canPlayNatively = mediaElement.canPlayType(mimeType) != '';

      // If we can't play natively, then src= isn't an option.
      if (!canPlayNatively) {
        return false;
      }

      const canPlayMediaSource =
          shaka.media.ManifestParser.isSupported(mimeType);

      // If MediaSource isn't an option, the native option is our only chance.
      if (!canPlayMediaSource) {
        return true;
      }

      // If we land here, both are feasible.
      goog.asserts.assert(canPlayNatively && canPlayMediaSource,
          'Both native and MSE playback should be possible!');

      // We would prefer MediaSource in some cases, and src= in others.  For
      // example, Android has native HLS, but we'd prefer our own MediaSource
      // version there.
      if (MimeUtils.isHlsType(mimeType)) {
        // Native HLS can be preferred on any platform via this flag:
        if (this.config_.streaming.preferNativeHls) {
          return true;
        }

        // Native FairPlay HLS can be preferred on Apple platfforms.
        if (Platform.isApple() &&
            (this.config_.drm.servers['com.apple.fps'] ||
            this.config_.drm.servers['com.apple.fps.1_0'])) {
          return this.config_.streaming.useNativeHlsForFairPlay;
        }

        // For Safari, we have an older flag which only applies to this one
        // browser:
        if (Platform.isApple()) {
          return this.config_.streaming.useNativeHlsOnSafari;
        }
      }

      // In all other cases, we prefer MediaSource.
      return false;
    }

    // Unless there are good reasons to use src= (single-file playback or native
    // HLS), we prefer MediaSource.  So the final return value for choosing src=
    // is false.
    return false;
  }

  /**
   * Initializes the media source engine.
   *
   * @return {!Promise}
   * @private
   */
  async initializeMediaSourceEngineInner_() {
    goog.asserts.assert(
        shaka.util.Platform.supportsMediaSource(),
        'We should not be initializing media source on a platform that ' +
            'does not support media source.');
    goog.asserts.assert(
        this.video_,
        'We should have a media element when initializing media source.');
    goog.asserts.assert(
        this.mediaSourceEngine_ == null,
        'We should not have a media source engine yet.');

    this.makeStateChangeEvent_('media-source');

    // When changing text visibility we need to update both the text displayer
    // and streaming engine because we don't always stream text. To ensure
    // that the text displayer and streaming engine are always in sync, wait
    // until they are both initialized before setting the initial value.
    const textDisplayerFactory = this.config_.textDisplayFactory;
    const textDisplayer = textDisplayerFactory();
    if (textDisplayer.configure) {
      textDisplayer.configure(this.config_.textDisplayer);
    } else {
      shaka.Deprecate.deprecateFeature(5,
          'Text displayer w/ configure',
          'Text displayer should have a "configure" method!');
    }
    this.lastTextFactory_ = textDisplayerFactory;

    const mediaSourceEngine = this.createMediaSourceEngine(
        this.video_,
        textDisplayer,
        (metadata, offset, endTime) => {
          this.processTimedMetadataMediaSrc_(metadata, offset, endTime);
        },
        this.lcevcDec_);
    mediaSourceEngine.configure(this.config_.mediaSource);
    const {segmentRelativeVttTiming} = this.config_.manifest;
    mediaSourceEngine.setSegmentRelativeVttTiming(segmentRelativeVttTiming);

    // Wait for media source engine to finish opening. This promise should
    // NEVER be rejected as per the media source engine implementation.
    await mediaSourceEngine.open();

    // Wait until it is ready to actually store the reference.
    this.mediaSourceEngine_ = mediaSourceEngine;
  }

  /**
   * Starts loading the content described by the parsed manifest.
   *
   * @param {number} startTimeOfLoad
   * @param {?shaka.extern.Variant} prefetchedVariant
   * @param {!Map.<number, shaka.media.SegmentPrefetch>} segmentPrefetchById
   * @return {!Promise}
   * @private
   */
  async loadInner_(startTimeOfLoad, prefetchedVariant, segmentPrefetchById) {
    goog.asserts.assert(
        this.video_, 'We should have a media element by now.');
    goog.asserts.assert(
        this.manifest_, 'The manifest should already be parsed.');
    goog.asserts.assert(
        this.assetUri_, 'We should have an asset uri by now.');
    goog.asserts.assert(
        this.abrManager_, 'We should have an abr manager by now.');

    this.makeStateChangeEvent_('load');

    const mediaElement = this.video_;
    this.playRateController_ = new shaka.media.PlayRateController({
      getRate: () => mediaElement.playbackRate,
      getDefaultRate: () => mediaElement.defaultPlaybackRate,
      setRate: (rate) => { mediaElement.playbackRate = rate; },
      movePlayhead: (delta) => { mediaElement.currentTime += delta; },
    });

    const updateStateHistory = () => this.updateStateHistory_();
    const onRateChange = () => this.onRateChange_();
    this.loadEventManager_.listen(
        mediaElement, 'playing', updateStateHistory);
    this.loadEventManager_.listen(mediaElement, 'pause', updateStateHistory);
    this.loadEventManager_.listen(mediaElement, 'ended', updateStateHistory);
    this.loadEventManager_.listen(mediaElement, 'ratechange', onRateChange);

    // Check the status of the LCEVC Dec Object. Reset, create, or close
    // depending on the config.
    this.setupLcevc_(this.config_);

    this.currentTextLanguage_ = this.config_.preferredTextLanguage;
    this.currentTextRole_ = this.config_.preferredTextRole;
    this.currentTextForced_ = this.config_.preferForcedSubs;

    shaka.Player.applyPlayRange_(this.manifest_.presentationTimeline,
        this.config_.playRangeStart,
        this.config_.playRangeEnd);

    this.abrManager_.init((variant, clearBuffer, safeMargin) => {
      return this.switch_(variant, clearBuffer, safeMargin);
    });
    this.abrManager_.setMediaElement(mediaElement);
    this.abrManager_.setCmsdManager(this.cmsdManager_);

    this.streamingEngine_ = this.createStreamingEngine();
    this.streamingEngine_.configure(this.config_.streaming);

    // Set the load mode to "loaded with media source" as late as possible so
    // that public methods won't try to access internal components until
    // they're all initialized. We MUST switch to loaded before calling
    // "streaming" so that they can access internal information.
    this.loadMode_ = shaka.Player.LoadMode.MEDIA_SOURCE;

    if (mediaElement.textTracks) {
      this.loadEventManager_.listen(
          mediaElement.textTracks, 'addtrack', (e) => {
            const trackEvent = /** @type {!TrackEvent} */(e);
            if (trackEvent.track) {
              const track = trackEvent.track;
              goog.asserts.assert(
                  track instanceof TextTrack, 'Wrong track type!');

              switch (track.kind) {
                case 'chapters':
                  this.activateChaptersTrack_(track);
                  break;
              }
            }
          });
    }

    // The event must be fired after we filter by restrictions but before the
    // active stream is picked to allow those listening for the "streaming"
    // event to make changes before streaming starts.
    this.dispatchEvent(shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.Streaming));

    // Pick the initial streams to play.
    // Unless the user has already picked a variant, anyway, by calling
    // selectVariantTrack before this loading stage.
    let initialVariant = prefetchedVariant;
    const activeVariant = this.streamingEngine_.getCurrentVariant();
    if (!activeVariant && !initialVariant) {
      initialVariant = this.chooseVariant_(/* initialSelection= */ true);
      goog.asserts.assert(initialVariant, 'Must choose an initial variant!');
    }

    // Lazy-load the stream, so we will have enough info to make the playhead.
    const createSegmentIndexPromises = [];
    const toLazyLoad = activeVariant || initialVariant;
    for (const stream of [toLazyLoad.video, toLazyLoad.audio]) {
      if (stream && !stream.segmentIndex) {
        createSegmentIndexPromises.push(stream.createSegmentIndex());
      }
    }
    if (createSegmentIndexPromises.length > 0) {
      await Promise.all(createSegmentIndexPromises);
    }

    if (this.parser_ && this.parser_.onInitialVariantChosen) {
      this.parser_.onInitialVariantChosen(toLazyLoad);
    }

    shaka.Player.applyPlayRange_(this.manifest_.presentationTimeline,
        this.config_.playRangeStart,
        this.config_.playRangeEnd);


    const setupPlayhead = (startTime) => {
      this.playhead_ = this.createPlayhead(startTime);
      this.playheadObservers_ =
          this.createPlayheadObserversForMSE_(startTimeOfLoad);

      // We need to start the buffer management code near the end because it
      // will set the initial buffering state and that depends on other
      // components being initialized.
      const rebufferThreshold = Math.max(
          this.manifest_.minBufferTime,
          this.config_.streaming.rebufferingGoal);
      this.startBufferManagement_(mediaElement, rebufferThreshold);
    };

    if (!this.config_.streaming.startAtSegmentBoundary) {
      setupPlayhead(this.startTime_);
    }

    // Now we can switch to the initial variant.
    if (!activeVariant) {
      goog.asserts.assert(initialVariant,
          'Must have choosen an initial variant!');

      // Now that we have initial streams, we may adjust the start time to
      // align to a segment boundary.
      if (this.config_.streaming.startAtSegmentBoundary) {
        const timeline = this.manifest_.presentationTimeline;
        let initialTime = this.startTime_ || this.video_.currentTime;
        const seekRangeStart = timeline.getSeekRangeStart();
        const seekRangeEnd = timeline.getSeekRangeEnd();
        if (initialTime < seekRangeStart) {
          initialTime = seekRangeStart;
        } else if (initialTime > seekRangeEnd) {
          initialTime = seekRangeEnd;
        }
        const startTime = await this.adjustStartTime_(
            initialVariant, initialTime);
        setupPlayhead(startTime);
      }

      this.switchVariant_(initialVariant, /* fromAdaptation= */ true,
          /* clearBuffer= */ false, /* safeMargin= */ 0);
    }

    this.playhead_.ready();

    // Decide if text should be shown automatically.
    // similar to video/audio track, we would skip switch initial text track
    // if user already pick text track (via selectTextTrack api)
    const activeTextTrack = this.getTextTracks().find((t) => t.active);

    if (!activeTextTrack) {
      const initialTextStream = this.chooseTextStream_();

      if (initialTextStream) {
        this.addTextStreamToSwitchHistory_(
            initialTextStream, /* fromAdaptation= */ true);
      }

      if (initialVariant) {
        this.setInitialTextState_(initialVariant, initialTextStream);
      }

      // Don't initialize with a text stream unless we should be streaming
      // text.
      if (initialTextStream && this.shouldStreamText_()) {
        this.streamingEngine_.switchTextStream(initialTextStream);
      }
    }


    // Start streaming content. This will start the flow of content down to
    // media source.
    await this.streamingEngine_.start(segmentPrefetchById);

    if (this.config_.abr.enabled) {
      this.abrManager_.enable();
      this.onAbrStatusChanged_();
    }

    // Dispatch a 'trackschanged' event now that all initial filtering is
    // done.
    this.onTracksChanged_();

    // Now that we've filtered out variants that aren't compatible with the
    // active one, update abr manager with filtered variants.
    // NOTE: This may be unnecessary.  We've already chosen one codec in
    // chooseCodecsAndFilterManifest_ before we started streaming.  But it
    // doesn't hurt, and this will all change when we start using
    // MediaCapabilities and codec switching.
    // TODO(#1391): Re-evaluate with MediaCapabilities and codec switching.
    this.updateAbrManagerVariants_();

    const hasPrimary = this.manifest_.variants.some((v) => v.primary);
    if (!this.config_.preferredAudioLanguage && !hasPrimary) {
      shaka.log.warning('No preferred audio language set.  ' +
          'We have chosen an arbitrary language initially');
    }

    const isLive = this.isLive();

    if ((isLive && (this.config_.streaming.liveSync ||
        this.manifest_.serviceDescription ||
        this.config_.streaming.liveSyncPanicMode)) ||
        this.config_.streaming.vodDynamicPlaybackRate) {
      const onTimeUpdate = () => this.onTimeUpdate_();
      this.loadEventManager_.listen(mediaElement, 'timeupdate', onTimeUpdate);
    } else if (!isLive) {
      const onVideoProgress = () => this.onVideoProgress_();
      this.loadEventManager_.listen(
          mediaElement, 'timeupdate', onVideoProgress);
      this.onVideoProgress_();
    }

    if (this.adManager_) {
      this.adManager_.onManifestUpdated(isLive);
    }

    this.fullyLoaded_ = true;

    // Wait for the 'loadedmetadata' event to measure load() latency.
    this.loadEventManager_.listenOnce(mediaElement, 'loadedmetadata', () => {
      const now = Date.now() / 1000;
      const delta = now - startTimeOfLoad;
      this.stats_.setLoadLatency(delta);
    });
  }

  /**
   * Initializes the DRM engine for use by src equals.
   *
   * @param {string} mimeType
   * @return {!Promise}
   * @private
   */
  async initializeSrcEqualsDrmInner_(mimeType) {
    const ContentType = shaka.util.ManifestParserUtils.ContentType;

    goog.asserts.assert(
        this.networkingEngine_,
        '|onInitializeSrcEqualsDrm_| should never be called after |destroy|');
    goog.asserts.assert(
        this.config_,
        '|onInitializeSrcEqualsDrm_| should never be called after |destroy|');

    const startTime = Date.now() / 1000;
    let firstEvent = true;

    this.drmEngine_ = this.createDrmEngine({
      netEngine: this.networkingEngine_,
      onError: (e) => {
        this.onError_(e);
      },
      onKeyStatus: (map) => {
        // According to this.onKeyStatus_, we can't even use this information
        // in src= mode, so this is just a no-op.
      },
      onExpirationUpdated: (id, expiration) => {
        const event = shaka.Player.makeEvent_(
            shaka.util.FakeEvent.EventName.ExpirationUpdated);
        this.dispatchEvent(event);
      },
      onEvent: (e) => {
        this.dispatchEvent(e);
        if (e.type == shaka.util.FakeEvent.EventName.DrmSessionUpdate &&
            firstEvent) {
          firstEvent = false;
          const now = Date.now() / 1000;
          const delta = now - startTime;
          this.stats_.setDrmTime(delta);
        }
      },
    });

    this.drmEngine_.configure(this.config_.drm);

    // TODO: Instead of feeding DrmEngine with Variants, we should refactor
    // DrmEngine so that it takes a minimal config derived from Variants.  In
    // cases like this one or in removal of stored content, the details are
    // largely unimportant.  We should have a saner way to initialize
    // DrmEngine.
    // That would also insulate DrmEngine from manifest changes in the future.
    // For now, that is time-consuming and this synthetic Variant is easy, so
    // I'm putting it off.  Since this is only expected to be used for native
    // HLS in Safari, this should be safe. -JCP
    /** @type {shaka.extern.Variant} */
    const variant = {
      id: 0,
      language: 'und',
      disabledUntilTime: 0,
      primary: false,
      audio: null,
      video: {
        id: 0,
        originalId: null,
        groupId: null,
        createSegmentIndex: () => Promise.resolve(),
        segmentIndex: null,
        mimeType: mimeType ? shaka.util.MimeUtils.getBasicType(mimeType) : '',
        codecs: mimeType ? shaka.util.MimeUtils.getCodecs(mimeType) : '',
        encrypted: true,
        drmInfos: [],  // Filled in by DrmEngine config.
        keyIds: new Set(),
        language: 'und',
        originalLanguage: null,
        label: null,
        type: ContentType.VIDEO,
        primary: false,
        trickModeVideo: null,
        emsgSchemeIdUris: null,
        roles: [],
        forced: false,
        channelsCount: null,
        audioSamplingRate: null,
        spatialAudio: false,
        closedCaptions: null,
        accessibilityPurpose: null,
        external: false,
        fastSwitching: false,
        fullMimeTypes: new Set(),
      },
      bandwidth: 100,
      allowedByApplication: true,
      allowedByKeySystem: true,
      decodingInfos: [],
    };
    variant.video.fullMimeTypes.add(shaka.util.MimeUtils.getFullType(
        variant.video.mimeType, variant.video.codecs));

    this.drmEngine_.setSrcEquals(/* srcEquals= */ true);
    await this.drmEngine_.initForPlayback(
        [variant], /* offlineSessionIds= */ []);
    await this.drmEngine_.attach(this.video_);
  }

  /**
   * Passes the asset URI along to the media element, so it can be played src
   * equals style.
   *
   * @param {number} startTimeOfLoad
   * @param {string} mimeType
   * @return {!Promise}
   *
   * @private
   */
  async srcEqualsInner_(startTimeOfLoad, mimeType) {
    this.makeStateChangeEvent_('src-equals');

    goog.asserts.assert(
        this.video_, 'We should have a media element when loading.');
    goog.asserts.assert(
        this.assetUri_, 'We should have a valid uri when loading.');

    const mediaElement = this.video_;

    this.playhead_ = new shaka.media.SrcEqualsPlayhead(mediaElement);

    // This flag is used below in the language preference setup to check if
    // this load was canceled before the necessary awaits completed.
    let unloaded = false;
    this.cleanupOnUnload_.push(() => {
      unloaded = true;
    });

    if (this.startTime_ != null) {
      this.playhead_.setStartTime(this.startTime_);
    }

    this.playRateController_ = new shaka.media.PlayRateController({
      getRate: () => mediaElement.playbackRate,
      getDefaultRate: () => mediaElement.defaultPlaybackRate,
      setRate: (rate) => { mediaElement.playbackRate = rate; },
      movePlayhead: (delta) => { mediaElement.currentTime += delta; },
    });

    // We need to start the buffer management code near the end because it
    // will set the initial buffering state and that depends on other
    // components being initialized.
    const rebufferThreshold = this.config_.streaming.rebufferingGoal;
    this.startBufferManagement_(mediaElement, rebufferThreshold);

    // Add all media element listeners.
    const updateStateHistory = () => this.updateStateHistory_();
    const onRateChange = () => this.onRateChange_();
    this.loadEventManager_.listen(
        mediaElement, 'playing', updateStateHistory);
    this.loadEventManager_.listen(mediaElement, 'pause', updateStateHistory);
    this.loadEventManager_.listen(mediaElement, 'ended', updateStateHistory);
    this.loadEventManager_.listen(mediaElement, 'ratechange', onRateChange);

    // Wait for the 'loadedmetadata' event to measure load() latency, but only
    // if preload is set in a way that would result in this event firing
    // automatically.
    // See https://github.com/shaka-project/shaka-player/issues/2483
    if (mediaElement.preload != 'none') {
      this.loadEventManager_.listenOnce(
          mediaElement, 'loadedmetadata', () => {
            const now = Date.now() / 1000;
            const delta = now - startTimeOfLoad;
            this.stats_.setLoadLatency(delta);
          });
    }

    // The audio tracks are only available on Safari at the moment, but this
    // drives the tracks API for Safari's native HLS. So when they change,
    // fire the corresponding Shaka Player event.
    if (mediaElement.audioTracks) {
      this.loadEventManager_.listen(mediaElement.audioTracks, 'addtrack',
          () => this.onTracksChanged_());
      this.loadEventManager_.listen(mediaElement.audioTracks, 'removetrack',
          () => this.onTracksChanged_());
      this.loadEventManager_.listen(mediaElement.audioTracks, 'change',
          () => this.onTracksChanged_());
    }

    if (mediaElement.textTracks) {
      this.loadEventManager_.listen(
          mediaElement.textTracks, 'addtrack', (e) => {
            const trackEvent = /** @type {!TrackEvent} */(e);
            if (trackEvent.track) {
              const track = trackEvent.track;
              goog.asserts.assert(
                  track instanceof TextTrack, 'Wrong track type!');

              switch (track.kind) {
                case 'metadata':
                  this.processTimedMetadataSrcEqls_(track);
                  break;

                case 'chapters':
                  this.activateChaptersTrack_(track);
                  break;

                default:
                  this.onTracksChanged_();
                  break;
              }
            }
          });

      this.loadEventManager_.listen(
          mediaElement.textTracks, 'removetrack',
          () => this.onTracksChanged_());
      this.loadEventManager_.listen(
          mediaElement.textTracks, 'change',
          () => this.onTracksChanged_());
    }

    // By setting |src| we are done "loading" with src=. We don't need to set
    // the current time because |playhead| will do that for us.
    mediaElement.src = this.cmcdManager_.appendSrcData(
        this.assetUri_, mimeType);

    // Tizen 3 / WebOS won't load anything unless you call load() explicitly,
    // no matter the value of the preload attribute.  This is harmful on some
    // other platforms by triggering unbounded loading of media data, but is
    // necessary here.
    if (shaka.util.Platform.isTizen() || shaka.util.Platform.isWebOS()) {
      mediaElement.load();
    }

    // In Safari using HLS won't load anything unless you call load()
    // explicitly, no matter the value of the preload attribute.
    // Note: this only happens when there are not autoplay.
    if (mediaElement.preload != 'none' && !mediaElement.autoplay &&
        shaka.util.MimeUtils.isHlsType(mimeType) &&
        shaka.util.Platform.safariVersion()) {
      mediaElement.load();
    }

    // Set the load mode last so that we know that all our components are
    // initialized.
    this.loadMode_ = shaka.Player.LoadMode.SRC_EQUALS;

    // The event doesn't mean as much for src= playback, since we don't
    // control streaming.  But we should fire it in this path anyway since
    // some applications may be expecting it as a life-cycle event.
    this.dispatchEvent(shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.Streaming));

    // The "load" Promise is resolved when we have loaded the metadata.  If we
    // wait for the full data, that won't happen on Safari until the play
    // button is hit.
    const fullyLoaded = new shaka.util.PublicPromise();
    shaka.util.MediaReadyState.waitForReadyState(mediaElement,
        HTMLMediaElement.HAVE_METADATA,
        this.loadEventManager_,
        () => {
          this.playhead_.ready();
          fullyLoaded.resolve();
        });

    // We can't switch to preferred languages, though, until the data is
    // loaded.
    shaka.util.MediaReadyState.waitForReadyState(mediaElement,
        HTMLMediaElement.HAVE_CURRENT_DATA,
        this.loadEventManager_,
        async () => {
          this.setupPreferredAudioOnSrc_();

          // Applying the text preference too soon can result in it being
          // reverted.  Wait for native HLS to pick something first.
          const textTracks = this.getFilteredTextTracks_();
          if (!textTracks.find((t) => t.mode != 'disabled')) {
            await new Promise((resolve) => {
              this.loadEventManager_.listenOnce(
                  mediaElement.textTracks, 'change', resolve);

              // We expect the event to fire because it does on Safari.
              // But in case it doesn't on some other platform or future
              // version, move on in 1 second no matter what.  This keeps the
              // language settings from being completely ignored if something
              // goes wrong.
              new shaka.util.Timer(resolve).tickAfter(1);
            });
          } else if (textTracks.length > 0) {
            this.isTextVisible_ = true;
          }

          // If we have moved on to another piece of content while waiting for
          // the above event/timer, we should not change tracks here.
          if (unloaded) {
            return;
          }

          this.setupPreferredTextOnSrc_();
        });

    if (mediaElement.error) {
      // Already failed!
      fullyLoaded.reject(this.videoErrorToShakaError_());
    } else if (mediaElement.preload == 'none') {
      shaka.log.alwaysWarn(
          'With <video preload="none">, the browser will not load anything ' +
          'until play() is called. We are unable to measure load latency ' +
          'in a meaningful way, and we cannot provide track info yet. ' +
          'Please do not use preload="none" with Shaka Player.');
      // We can't wait for an event load loadedmetadata, since that will be
      // blocked until a user interaction.  So resolve the Promise now.
      fullyLoaded.resolve();
    }

    this.loadEventManager_.listenOnce(mediaElement, 'error', () => {
      fullyLoaded.reject(this.videoErrorToShakaError_());
    });

    await fullyLoaded;

    const isLive = this.isLive();

    if ((isLive && (this.config_.streaming.liveSync ||
        this.config_.streaming.liveSyncPanicMode)) ||
        this.config_.streaming.vodDynamicPlaybackRate) {
      const onTimeUpdate = () => this.onTimeUpdate_();
      this.loadEventManager_.listen(mediaElement, 'timeupdate', onTimeUpdate);
    } else if (!isLive) {
      const onVideoProgress = () => this.onVideoProgress_();
      this.loadEventManager_.listen(
          mediaElement, 'timeupdate', onVideoProgress);
      this.onVideoProgress_();
    }

    if (this.adManager_) {
      this.adManager_.onManifestUpdated(isLive);
      // There is no good way to detect when the manifest has been updated,
      // so we use seekRange().end so we can tell when it has been updated.
      if (isLive) {
        let prevSeekRangeEnd = this.seekRange().end;
        this.loadEventManager_.listen(mediaElement, 'progress', () => {
          const newSeekRangeEnd = this.seekRange().end;
          if (prevSeekRangeEnd != newSeekRangeEnd) {
            this.adManager_.onManifestUpdated(this.isLive());
            prevSeekRangeEnd = newSeekRangeEnd;
          }
        });
      }
    }

    this.fullyLoaded_ = true;
  }

  /**
   * This method setup the preferred audio using src=..
   *
   * @private
   */
  setupPreferredAudioOnSrc_() {
    const preferredAudioLanguage = this.config_.preferredAudioLanguage;

    // If the user has not selected a preference, the browser preference is
    // left.
    if (preferredAudioLanguage == '') {
      return;
    }

    const preferredVariantRole = this.config_.preferredVariantRole;
    this.selectAudioLanguage(preferredAudioLanguage, preferredVariantRole);
  }

  /**
   * This method setup the preferred text using src=.
   *
   * @private
   */
  setupPreferredTextOnSrc_() {
    const preferredTextLanguage = this.config_.preferredTextLanguage;

    // If the user has not selected a preference, the browser preference is
    // left.
    if (preferredTextLanguage == '') {
      return;
    }

    const preferForcedSubs = this.config_.preferForcedSubs;
    const preferredTextRole = this.config_.preferredTextRole;

    this.selectTextLanguage(preferredTextLanguage, preferredTextRole,
        preferForcedSubs);
  }

  /**
   * We're looking for metadata tracks to process id3 tags. One of the uses is
   * for ad info on LIVE streams
   *
   * @param {!TextTrack} track
   * @private
   */
  processTimedMetadataSrcEqls_(track) {
    if (track.kind != 'metadata') {
      return;
    }

    // Hidden mode is required for the cuechange event to launch correctly
    track.mode = 'hidden';
    this.loadEventManager_.listen(track, 'cuechange', () => {
      if (!track.activeCues) {
        return;
      }

      for (const cue of track.activeCues) {
        this.dispatchMetadataEvent_(cue.startTime, cue.endTime,
            cue.type, cue.value);

        if (this.adManager_) {
          this.adManager_.onCueMetadataChange(cue.value);
        }
      }
    });

    // In Safari the initial assignment does not always work, so we schedule
    // this process to be repeated several times to ensure that it has been put
    // in the correct mode.
    const timer = new shaka.util.Timer(() => {
      const textTracks = this.getMetadataTracks_();
      for (const textTrack of textTracks) {
        textTrack.mode = 'hidden';
      }
    }).tickNow().tickAfter(0.5);

    this.cleanupOnUnload_.push(() => {
      timer.stop();
    });
  }


  /**
   * @param {!Array.<shaka.extern.ID3Metadata>} metadata
   * @param {number} offset
   * @param {?number} segmentEndTime
   * @private
   */
  processTimedMetadataMediaSrc_(metadata, offset, segmentEndTime) {
    for (const sample of metadata) {
      if (sample.data && sample.cueTime && sample.frames) {
        const start = sample.cueTime + offset;
        let end = segmentEndTime;
        // This can happen when the ID3 info arrives in a previous segment.
        if (end && start > end) {
          end = start;
        }
        const metadataType = 'org.id3';
        for (const frame of sample.frames) {
          const payload = frame;
          this.dispatchMetadataEvent_(start, end, metadataType, payload);
        }

        if (this.adManager_) {
          this.adManager_.onHlsTimedMetadata(sample, start);
        }
      }
    }
  }


  /**
   * Construct and fire a Player.Metadata event
   *
   * @param {number} startTime
   * @param {?number} endTime
   * @param {string} metadataType
   * @param {shaka.extern.MetadataFrame} payload
   * @private
   */
  dispatchMetadataEvent_(startTime, endTime, metadataType, payload) {
    goog.asserts.assert(!endTime || startTime <= endTime,
        'Metadata start time should be less or equal to the end time!');
    const eventName = shaka.util.FakeEvent.EventName.Metadata;
    const data = new Map()
        .set('startTime', startTime)
        .set('endTime', endTime)
        .set('metadataType', metadataType)
        .set('payload', payload);
    this.dispatchEvent(shaka.Player.makeEvent_(eventName, data));
  }

  /**
   * Set the mode on a chapters track so that it loads.
   *
   * @param {?TextTrack} track
   * @private
   */
  activateChaptersTrack_(track) {
    if (!track || track.kind != 'chapters') {
      return;
    }

    // Hidden mode is required for the cuechange event to launch correctly and
    // get the cues and the activeCues
    track.mode = 'hidden';

    // In Safari the initial assignment does not always work, so we schedule
    // this process to be repeated several times to ensure that it has been put
    // in the correct mode.
    const timer = new shaka.util.Timer(() => {
      track.mode = 'hidden';
    }).tickNow().tickAfter(0.5);

    this.cleanupOnUnload_.push(() => {
      timer.stop();
    });
  }

  /**
   * Releases all of the mutexes of the player. Meant for use by the tests.
   * @export
   */
  releaseAllMutexes() {
    this.mutex_.releaseAll();
  }

  /**
   * Create a new DrmEngine instance. This may be replaced by tests to create
   * fake instances. Configuration and initialization will be handled after
   * |createDrmEngine|.
   *
   * @param {shaka.media.DrmEngine.PlayerInterface} playerInterface
   * @return {!shaka.media.DrmEngine}
   */
  createDrmEngine(playerInterface) {
    return new shaka.media.DrmEngine(playerInterface);
  }

  /**
   * Creates a new instance of NetworkingEngine.  This can be replaced by tests
   * to create fake instances instead.
   *
   * @param {(function():?shaka.media.PreloadManager)=} getPreloadManager
   * @return {!shaka.net.NetworkingEngine}
   */
  createNetworkingEngine(getPreloadManager) {
    if (!getPreloadManager) {
      getPreloadManager = () => null;
    }

    const getAbrManager = () => {
      if (getPreloadManager()) {
        return getPreloadManager().getAbrManager();
      } else {
        return this.abrManager_;
      }
    };
    const getParser = () => {
      if (getPreloadManager()) {
        return getPreloadManager().getParser();
      } else {
        return this.parser_;
      }
    };
    const lateQueue = (fn) => {
      if (getPreloadManager()) {
        getPreloadManager().addQueuedOperation(true, fn);
      } else {
        fn();
      }
    };
    const dispatchEvent = (event) => {
      if (getPreloadManager()) {
        getPreloadManager().dispatchEvent(event);
      } else {
        this.dispatchEvent(event);
      }
    };
    const getStats = () => {
      if (getPreloadManager()) {
        return getPreloadManager().getStats();
      } else {
        return this.stats_;
      }
    };
    /** @type {shaka.net.NetworkingEngine.onProgressUpdated} */
    const onProgressUpdated_ = (deltaTimeMs,
        bytesDownloaded, allowSwitch, request) => {
      // In some situations, such as during offline storage, the abr manager
      // might not yet exist. Therefore, we need to check if abr manager has
      // been initialized before using it.
      const abrManager = getAbrManager();
      if (abrManager) {
        abrManager.segmentDownloaded(deltaTimeMs, bytesDownloaded,
            allowSwitch, request);
      }
    };
    /** @type {shaka.net.NetworkingEngine.OnHeadersReceived} */
    const onHeadersReceived_ = (headers, request, requestType) => {
      // Release a 'downloadheadersreceived' event.
      const name = shaka.util.FakeEvent.EventName.DownloadHeadersReceived;
      const data = new Map()
          .set('headers', headers)
          .set('request', request)
          .set('requestType', requestType);
      dispatchEvent(shaka.Player.makeEvent_(name, data));
      lateQueue(() => {
        if (this.cmsdManager_) {
          this.cmsdManager_.processHeaders(headers);
        }
      });
    };
    /** @type {shaka.net.NetworkingEngine.OnDownloadFailed} */
    const onDownloadFailed_ = (request, error, httpResponseCode, aborted) => {
      // Release a 'downloadfailed' event.
      const name = shaka.util.FakeEvent.EventName.DownloadFailed;
      const data = new Map()
          .set('request', request)
          .set('error', error)
          .set('httpResponseCode', httpResponseCode)
          .set('aborted', aborted);
      dispatchEvent(shaka.Player.makeEvent_(name, data));
    };
    /** @type {shaka.net.NetworkingEngine.OnRequest} */
    const onRequest_ = (type, request, context) => {
      lateQueue(() => {
        this.cmcdManager_.applyData(type, request, context);
      });
    };

    /** @type {shaka.net.NetworkingEngine.OnRetry} */
    const onRetry_ = (type, context, newUrl, oldUrl) => {
      const parser = getParser();
      if (parser && parser.banLocation) {
        parser.banLocation(oldUrl);
      }
    };

    /** @type {shaka.net.NetworkingEngine.OnResponse} */
    const onResponse_ = (type, response, context) => {
      const bytesDownloaded = response.data.byteLength;
      const stats = getStats();
      if (stats) {
        stats.addBytesDownloaded(bytesDownloaded);
      }
    };

    return new shaka.net.NetworkingEngine(
        onProgressUpdated_, onHeadersReceived_, onDownloadFailed_, onRequest_,
        onRetry_, onResponse_);
  }

  /**
   * Creates a new instance of Playhead.  This can be replaced by tests to
   * create fake instances instead.
   *
   * @param {?number} startTime
   * @return {!shaka.media.Playhead}
   */
  createPlayhead(startTime) {
    goog.asserts.assert(this.manifest_, 'Must have manifest');
    goog.asserts.assert(this.video_, 'Must have video');
    return new shaka.media.MediaSourcePlayhead(
        this.video_,
        this.manifest_,
        this.config_.streaming,
        startTime,
        () => this.onSeek_(),
        (event) => this.dispatchEvent(event));
  }

  /**
   * Create the observers for MSE playback. These observers are responsible for
   * notifying the app and player of specific events during MSE playback.
   *
   * @param {number} startTimeOfLoad
   * @return {!shaka.media.PlayheadObserverManager}
   * @private
   */
  createPlayheadObserversForMSE_(startTimeOfLoad) {
    goog.asserts.assert(this.manifest_, 'Must have manifest');
    goog.asserts.assert(this.regionTimeline_, 'Must have region timeline');
    goog.asserts.assert(this.video_, 'Must have video element');

    const startsPastZero = this.isLive() || startTimeOfLoad > 0;

    // Create the region observer. This will allow us to notify the app when we
    // move in and out of timeline regions.
    const regionObserver = new shaka.media.RegionObserver(
        this.regionTimeline_, startsPastZero);

    regionObserver.addEventListener('enter', (event) => {
      /** @type {shaka.extern.TimelineRegionInfo} */
      const region = event['region'];
      this.onRegionEvent_(
          shaka.util.FakeEvent.EventName.TimelineRegionEnter, region);
    });

    regionObserver.addEventListener('exit', (event) => {
      /** @type {shaka.extern.TimelineRegionInfo} */
      const region = event['region'];
      this.onRegionEvent_(
          shaka.util.FakeEvent.EventName.TimelineRegionExit, region);
    });

    regionObserver.addEventListener('skip', (event) => {
      /** @type {shaka.extern.TimelineRegionInfo} */
      const region = event['region'];
      /** @type {boolean} */
      const seeking = event['seeking'];
      // If we are seeking, we don't want to surface the enter/exit events since
      // they didn't play through them.
      if (!seeking) {
        this.onRegionEvent_(
            shaka.util.FakeEvent.EventName.TimelineRegionEnter, region);
        this.onRegionEvent_(
            shaka.util.FakeEvent.EventName.TimelineRegionExit, region);
      }
    });

    // Now that we have all our observers, create a manager for them.
    const manager = new shaka.media.PlayheadObserverManager(this.video_);
    manager.manage(regionObserver);
    if (this.qualityObserver_) {
      manager.manage(this.qualityObserver_);
    }
    return manager;
  }

  /**
   * Initialize and start the buffering system (observer and timer) so that we
   * can monitor our buffer lead during playback.
   *
   * @param {!HTMLMediaElement} mediaElement
   * @param {number} rebufferingGoal
   * @private
   */
  startBufferManagement_(mediaElement, rebufferingGoal) {
    goog.asserts.assert(
        !this.bufferObserver_,
        'No buffering observer should exist before initialization.');

    // Give dummy values, will be updated below.
    this.bufferObserver_ = new shaka.media.BufferingObserver(1, 2);

    // Force us back to a buffering state. This ensure everything is starting in
    // the same state.
    this.bufferObserver_.setState(shaka.media.BufferingObserver.State.STARVING);
    this.updateBufferingSettings_(rebufferingGoal);
    this.updateBufferState_();

    this.loadEventManager_.listen(mediaElement, 'waiting',
        (e) => this.pollBufferState_());
    this.loadEventManager_.listen(mediaElement, 'stalled',
        (e) => this.pollBufferState_());
    this.loadEventManager_.listen(mediaElement, 'canplaythrough',
        (e) => this.pollBufferState_());
    this.loadEventManager_.listen(mediaElement, 'progress',
        (e) => this.pollBufferState_());
  }

  /**
   * Updates the buffering thresholds based on the new rebuffering goal.
   *
   * @param {number} rebufferingGoal
   * @private
   */
  updateBufferingSettings_(rebufferingGoal) {
    // The threshold to transition back to satisfied when starving.
    const starvingThreshold = rebufferingGoal;
    // The threshold to transition into starving when satisfied.
    // We use a "typical" threshold, unless the rebufferingGoal is unusually
    // low.
    // Then we force the value down to half the rebufferingGoal, since
    // starvingThreshold must be strictly larger than satisfiedThreshold for the
    // logic in BufferingObserver to work correctly.
    const satisfiedThreshold = Math.min(
        shaka.Player.TYPICAL_BUFFERING_THRESHOLD_, rebufferingGoal / 2);

    this.bufferObserver_.setThresholds(starvingThreshold, satisfiedThreshold);
  }

  /**
   * This method is called periodically to check what the buffering observer
   * says so that we can update the rest of the buffering behaviours.
   *
   * @private
   */
  pollBufferState_() {
    goog.asserts.assert(
        this.video_,
        'Need a media element to update the buffering observer');

    goog.asserts.assert(
        this.bufferObserver_,
        'Need a buffering observer to update');

    let bufferedToEnd;
    switch (this.loadMode_) {
      case shaka.Player.LoadMode.SRC_EQUALS:
        bufferedToEnd = this.isBufferedToEndSrc_();
        break;
      case shaka.Player.LoadMode.MEDIA_SOURCE:
        bufferedToEnd = this.isBufferedToEndMS_();
        break;
      default:
        bufferedToEnd = false;
        break;
    }

    const bufferLead = shaka.media.TimeRangesUtils.bufferedAheadOf(
        this.video_.buffered,
        this.video_.currentTime);

    const stateChanged = this.bufferObserver_.update(bufferLead, bufferedToEnd);

    // If the state changed, we need to surface the event.
    if (stateChanged) {
      this.updateBufferState_();
    }
  }

  /**
   * Create a new media source engine. This will ONLY be replaced by tests as a
   * way to inject fake media source engine instances.
   *
   * @param {!HTMLMediaElement} mediaElement
   * @param {!shaka.extern.TextDisplayer} textDisplayer
   * @param {!function(!Array.<shaka.extern.ID3Metadata>, number, ?number)}
   *  onMetadata
   * @param {shaka.lcevc.Dec} lcevcDec
   *
   * @return {!shaka.media.MediaSourceEngine}
   */
  createMediaSourceEngine(mediaElement, textDisplayer, onMetadata, lcevcDec) {
    return new shaka.media.MediaSourceEngine(
        mediaElement,
        textDisplayer,
        onMetadata,
        lcevcDec);
  }

  /**
   * Create a new CMCD manager.
   *
   * @private
   */
  createCmcd_() {
    /** @type {shaka.util.CmcdManager.PlayerInterface} */
    const playerInterface = {
      getBandwidthEstimate: () => this.abrManager_ ?
        this.abrManager_.getBandwidthEstimate() : NaN,
      getBufferedInfo: () => this.getBufferedInfo(),
      getCurrentTime: () => this.video_ ? this.video_.currentTime : 0,
      getPlaybackRate: () => this.getPlaybackRate(),
      getNetworkingEngine: () => this.getNetworkingEngine(),
      getVariantTracks: () => this.getVariantTracks(),
      isLive: () => this.isLive(),
    };

    return new shaka.util.CmcdManager(playerInterface, this.config_.cmcd);
  }

  /**
   * Create a new CMSD manager.
   *
   * @private
   */
  createCmsd_() {
    return new shaka.util.CmsdManager(this.config_.cmsd);
  }

  /**
   * Creates a new instance of StreamingEngine.  This can be replaced by tests
   * to create fake instances instead.
   *
   * @return {!shaka.media.StreamingEngine}
   */
  createStreamingEngine() {
    goog.asserts.assert(
        this.abrManager_ && this.mediaSourceEngine_ && this.manifest_,
        'Must not be destroyed');

    /** @type {shaka.media.StreamingEngine.PlayerInterface} */
    const playerInterface = {
      getPresentationTime: () => this.playhead_ ? this.playhead_.getTime() : 0,
      getBandwidthEstimate: () => this.abrManager_.getBandwidthEstimate(),
      mediaSourceEngine: this.mediaSourceEngine_,
      netEngine: this.networkingEngine_,
      onError: (error) => this.onError_(error),
      onEvent: (event) => this.dispatchEvent(event),
      onManifestUpdate: () => this.onManifestUpdate_(),
      onSegmentAppended: (reference, stream) => {
        this.onSegmentAppended_(
            reference.startTime, reference.endTime, stream.type);
        if (this.abrManager_ && stream.fastSwitching &&
            reference.isPartial() && reference.isLastPartial()) {
          this.abrManager_.trySuggestStreams();
        }
      },
      onInitSegmentAppended: (position, initSegment) => {
        const mediaQuality = initSegment.getMediaQuality();
        if (mediaQuality && this.qualityObserver_) {
          this.qualityObserver_.addMediaQualityChange(mediaQuality, position);
        }
      },
      beforeAppendSegment: (contentType, segment) => {
        return this.drmEngine_.parseInbandPssh(contentType, segment);
      },
      onMetadata: (metadata, offset, endTime) => {
        this.processTimedMetadataMediaSrc_(metadata, offset, endTime);
      },
      disableStream: (stream, time) => this.disableStream(stream, time),
    };

    return new shaka.media.StreamingEngine(this.manifest_, playerInterface);
  }

  /**
   * Changes configuration settings on the Player.  This checks the names of
   * keys and the types of values to avoid coding errors.  If there are errors,
   * this logs them to the console and returns false.  Correct fields are still
   * applied even if there are other errors.  You can pass an explicit
   * <code>undefined</code> value to restore the default value.  This has two
   * modes of operation:
   *
   * <p>
   * First, this can be passed a single "plain" object.  This object should
   * follow the {@link shaka.extern.PlayerConfiguration} object.  Not all fields
   * need to be set; unset fields retain their old values.
   *
   * <p>
   * Second, this can be passed two arguments.  The first is the name of the key
   * to set.  This should be a '.' separated path to the key.  For example,
   * <code>'streaming.alwaysStreamText'</code>.  The second argument is the
   * value to set.
   *
   * @param {string|!Object} config This should either be a field name or an
   *   object.
   * @param {*=} value In the second mode, this is the value to set.
   * @return {boolean} True if the passed config object was valid, false if
   *   there were invalid entries.
   * @export
   */
  configure(config, value) {
    goog.asserts.assert(this.config_, 'Config must not be null!');
    goog.asserts.assert(typeof(config) == 'object' || arguments.length == 2,
        'String configs should have values!');

    // ('fieldName', value) format
    if (arguments.length == 2 && typeof(config) == 'string') {
      config = shaka.util.ConfigUtils.convertToConfigObject(config, value);
    }

    goog.asserts.assert(typeof(config) == 'object', 'Should be an object!');

    // Deprecate 'streaming.forceTransmuxTS' configuration.
    if (config['streaming'] && 'forceTransmuxTS' in config['streaming']) {
      shaka.Deprecate.deprecateFeature(5,
          'streaming.forceTransmuxTS configuration',
          'Please Use mediaSource.forceTransmux instead.');
      config['mediaSource']['mediaSource'] =
          config['streaming']['forceTransmuxTS'];
      delete config['streaming']['forceTransmuxTS'];
    }

    // Deprecate 'streaming.forceTransmux' configuration.
    if (config['streaming'] && 'forceTransmux' in config['streaming']) {
      shaka.Deprecate.deprecateFeature(5,
          'streaming.forceTransmux configuration',
          'Please Use mediaSource.forceTransmux instead.');
      config['mediaSource']['mediaSource'] =
          config['streaming']['forceTransmux'];
      delete config['streaming']['forceTransmux'];
    }

    // Deprecate 'streaming.useNativeHlsOnSafari' configuration.
    if (config['streaming'] && 'useNativeHlsOnSafari' in config['streaming']) {
      shaka.Deprecate.deprecateFeature(5,
          'streaming.useNativeHlsOnSafari configuration',
          'Please Use streaming.useNativeHlsForFairPlay or ' +
          'streaming.preferNativeHls instead.');
    }

    // Deprecate 'mediaSource.sourceBufferExtraFeatures' configuration.
    if (config['mediaSource'] &&
        'sourceBufferExtraFeatures' in config['mediaSource']) {
      shaka.Deprecate.deprecateFeature(5,
          'mediaSource.sourceBufferExtraFeatures configuration',
          'Please Use mediaSource.addExtraFeaturesToSourceBuffer() instead.');
      const sourceBufferExtraFeatures =
          config['mediaSource']['sourceBufferExtraFeatures'];
      config['mediaSource']['addExtraFeaturesToSourceBuffer'] = () => {
        return sourceBufferExtraFeatures;
      };
      delete config['mediaSource']['sourceBufferExtraFeatures'];
    }

    // If lowLatencyMode is enabled, and inaccurateManifestTolerance and
    // rebufferingGoal and segmentPrefetchLimit and baseDelay are not
    // specified, set inaccurateManifestTolerance to 0 and rebufferingGoal
    // to 0.01 and segmentPrefetchLimit to 2 and updateIntervalSeconds to
    // 0.1 and baseDelay to 100 by default for low latency streaming.
    if (config['streaming'] && config['streaming']['lowLatencyMode']) {
      if (config['streaming']['inaccurateManifestTolerance'] == undefined) {
        config['streaming']['inaccurateManifestTolerance'] = 0;
      }
      if (config['streaming']['rebufferingGoal'] == undefined) {
        config['streaming']['rebufferingGoal'] = 0.01;
      }
      if (config['streaming']['segmentPrefetchLimit'] == undefined) {
        config['streaming']['segmentPrefetchLimit'] = 2;
      }
      if (config['streaming']['updateIntervalSeconds'] == undefined) {
        config['streaming']['updateIntervalSeconds'] = 0.1;
      }
      if (config['streaming']['retryParameters'] == undefined) {
        config['streaming']['retryParameters'] = {};
      }
      if (config['streaming']['retryParameters']['baseDelay'] == undefined) {
        config['streaming']['retryParameters']['baseDelay'] = 100;
      }
      if (config['manifest'] == undefined) {
        config['manifest'] = {};
      }
      if (config['manifest']['retryParameters'] == undefined) {
        config['manifest']['retryParameters'] = {};
      }
      if (config['manifest']['retryParameters']['baseDelay'] == undefined) {
        config['manifest']['retryParameters']['baseDelay'] = 100;
      }
      if (config['drm'] == undefined) {
        config['drm'] = {};
      }
      if (config['drm']['retryParameters'] == undefined) {
        config['drm']['retryParameters'] = {};
      }
      if (config['drm']['retryParameters']['baseDelay'] == undefined) {
        config['drm']['retryParameters']['baseDelay'] = 100;
      }
    }
    const ret = shaka.util.PlayerConfiguration.mergeConfigObjects(
        this.config_, config, this.defaultConfig_());

    this.applyConfig_();
    return ret;
  }

  /**
   * Apply config changes.
   * @private
   */
  applyConfig_() {
    this.manifestFilterer_ = new shaka.media.ManifestFilterer(
        this.config_, this.maxHwRes_, this.drmEngine_);
    if (this.parser_) {
      const manifestConfig =
          shaka.util.ObjectUtils.cloneObject(this.config_.manifest);
      // Don't read video segments if the player is attached to an audio element
      if (this.video_ && this.video_.nodeName === 'AUDIO') {
        manifestConfig.disableVideo = true;
      }
      this.parser_.configure(manifestConfig);
    }
    if (this.drmEngine_) {
      this.drmEngine_.configure(this.config_.drm);
    }
    if (this.streamingEngine_) {
      this.streamingEngine_.configure(this.config_.streaming);

      // Need to apply the restrictions.
      // this.filterManifestWithRestrictions_() may throw.
      try {
        if (this.loadMode_ != shaka.Player.LoadMode.DESTROYED) {
          if (this.manifestFilterer_.filterManifestWithRestrictions(
              this.manifest_)) {
            this.onTracksChanged_();
          }
        }
      } catch (error) {
        this.onError_(error);
      }

      if (this.abrManager_) {
        // Update AbrManager variants to match these new settings.
        this.updateAbrManagerVariants_();
      }

      // If the streams we are playing are restricted, we need to switch.
      const activeVariant = this.streamingEngine_.getCurrentVariant();
      if (activeVariant) {
        if (!activeVariant.allowedByApplication ||
            !activeVariant.allowedByKeySystem) {
          shaka.log.debug('Choosing new variant after changing configuration');
          this.chooseVariantAndSwitch_();
        }
      }
    }
    if (this.networkingEngine_) {
      this.networkingEngine_.setForceHTTPS(this.config_.streaming.forceHTTPS);
    }

    if (this.mediaSourceEngine_) {
      this.mediaSourceEngine_.configure(this.config_.mediaSource);
      const {segmentRelativeVttTiming} = this.config_.manifest;
      this.mediaSourceEngine_.setSegmentRelativeVttTiming(
          segmentRelativeVttTiming);

      const textDisplayerFactory = this.config_.textDisplayFactory;
      if (this.lastTextFactory_ != textDisplayerFactory) {
        const displayer = textDisplayerFactory();
        if (displayer.configure) {
          displayer.configure(this.config_.textDisplayer);
        } else {
          shaka.Deprecate.deprecateFeature(5,
              'Text displayer w/ configure',
              'Text displayer should have a "configure" method!');
        }
        this.mediaSourceEngine_.setTextDisplayer(displayer);
        this.lastTextFactory_ = textDisplayerFactory;

        if (this.streamingEngine_) {
          // Reload the text stream, so the cues will load again.
          this.streamingEngine_.reloadTextStream();
        }
      } else {
        const displayer = this.mediaSourceEngine_.getTextDisplayer();
        if (displayer.configure) {
          displayer.configure(this.config_.textDisplayer);
        }
      }
    }
    if (this.abrManager_) {
      this.abrManager_.configure(this.config_.abr);
      // Simply enable/disable ABR with each call, since multiple calls to these
      // methods have no effect.
      if (this.config_.abr.enabled) {
        this.abrManager_.enable();
      } else {
        this.abrManager_.disable();
      }

      this.onAbrStatusChanged_();
    }
    if (this.bufferObserver_) {
      let rebufferThreshold = this.config_.streaming.rebufferingGoal;
      if (this.manifest_) {
        rebufferThreshold =
            Math.max(rebufferThreshold, this.manifest_.minBufferTime);
      }
      this.updateBufferingSettings_(rebufferThreshold);
    }

    if (this.manifest_) {
      shaka.Player.applyPlayRange_(this.manifest_.presentationTimeline,
          this.config_.playRangeStart,
          this.config_.playRangeEnd);
    }
    if (this.adManager_) {
      this.adManager_.configure(this.config_.ads);
    }
    if (this.cmcdManager_) {
      this.cmcdManager_.configure(this.config_.cmcd);
    }
    if (this.cmsdManager_) {
      this.cmsdManager_.configure(this.config_.cmsd);
    }
  }

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

    const ret = this.defaultConfig_();
    shaka.util.PlayerConfiguration.mergeConfigObjects(
        ret, this.config_, this.defaultConfig_());
    return ret;
  }

  /**
   * Return a reference to the current configuration. Modifications to the
   * returned value will affect the Player's active configuration. This method
   * is not exported as sharing configuration with external objects is not
   * supported.
   *
   * @return {shaka.extern.PlayerConfiguration}
   */
  getSharedConfiguration() {
    goog.asserts.assert(
        this.config_, 'Cannot call getSharedConfiguration after call destroy!');
    return this.config_;
  }

  /**
   * Returns the ratio of video length buffered compared to buffering Goal
   * @return {number}
   * @export
   */
  getBufferFullness() {
    if (this.video_) {
      const bufferedLength = this.video_.buffered.length;
      const bufferedEnd =
          bufferedLength ? this.video_.buffered.end(bufferedLength - 1) : 0;
      const bufferingGoal = this.getConfiguration().streaming.bufferingGoal;
      const lengthToBeBuffered = Math.min(this.video_.currentTime +
          bufferingGoal, this.seekRange().end);

      if (bufferedEnd >= lengthToBeBuffered) {
        return 1;
      } else if (bufferedEnd <= this.video_.currentTime) {
        return 0;
      } else if (bufferedEnd < lengthToBeBuffered) {
        return ((bufferedEnd - this.video_.currentTime) /
            (lengthToBeBuffered - this.video_.currentTime));
      }
    }
    return 0;
  }

  /**
   * Reset configuration to default.
   * @export
   */
  resetConfiguration() {
    goog.asserts.assert(this.config_, 'Cannot be destroyed');
    // Remove the old keys so we remove open-ended dictionaries like drm.servers
    // but keeps the same object reference.
    for (const key in this.config_) {
      delete this.config_[key];
    }

    shaka.util.PlayerConfiguration.mergeConfigObjects(
        this.config_, this.defaultConfig_(), this.defaultConfig_());
    this.applyConfig_();
  }

  /**
   * Get the current load mode.
   *
   * @return {shaka.Player.LoadMode}
   * @export
   */
  getLoadMode() {
    return this.loadMode_;
  }

  /**
   * Get the current manifest type.
   *
   * @return {?string}
   * @export
   */
  getManifestType() {
    if (!this.manifest_) {
      return null;
    }
    return this.manifest_.type;
  }

  /**
   * Get the media element that the player is currently using to play loaded
   * content. If the player has not loaded content, this will return
   * <code>null</code>.
   *
   * @return {HTMLMediaElement}
   * @export
   */
  getMediaElement() {
    return this.video_;
  }

  /**
   * @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
   */
  getNetworkingEngine() {
    return this.networkingEngine_;
  }

  /**
   * Get the uri to the asset that the player has loaded. If the player has not
   * loaded content, this will return <code>null</code>.
   *
   * @return {?string}
   * @export
   */
  getAssetUri() {
    return this.assetUri_;
  }

  /**
   * Returns a shaka.ads.AdManager instance, responsible for Dynamic
   * Ad Insertion functionality.
   *
   * @return {shaka.extern.IAdManager}
   * @export
   */
  getAdManager() {
    // NOTE: this clause is redundant, but it keeps the compiler from
    // inlining this function. Inlining leads to setting the adManager
    // not taking effect in the compiled build.
    // Closure has a @noinline flag, but apparently not all cases are
    // supported by it, and ours isn't.
    // If they expand support, we might be able to get rid of this
    // clause.
    if (!this.adManager_) {
      return null;
    }

    return this.adManager_;
  }

  /**
   * Get if the player is playing live content. If the player has not loaded
   * content, this will return <code>false</code>.
   *
   * @return {boolean}
   * @export
   */
  isLive() {
    if (this.manifest_) {
      return this.manifest_.presentationTimeline.isLive();
    }

    // For native HLS, the duration for live streams seems to be Infinity.
    if (this.video_ && this.video_.src) {
      return this.video_.duration == Infinity;
    }

    return false;
  }

  /**
   * Get if the player is playing in-progress content. If the player has not
   * loaded content, this will return <code>false</code>.
   *
   * @return {boolean}
   * @export
   */
  isInProgress() {
    return this.manifest_ ?
           this.manifest_.presentationTimeline.isInProgress() :
           false;
  }

  /**
   * Check if the manifest contains only audio-only content. If the player has
   * not loaded content, this will return <code>false</code>.
   *
   * <p>
   * The player does not support content that contain more than one type of
   * variants (i.e. mixing audio-only, video-only, audio-video). Content will be
   * filtered to only contain one type of variant.
   *
   * @return {boolean}
   * @export
   */
  isAudioOnly() {
    if (this.manifest_) {
      const variants = this.manifest_.variants;
      if (!variants.length) {
        return false;
      }

      // Note that if there are some audio-only variants and some audio-video
      // variants, the audio-only variants are removed during filtering.
      // Therefore if the first variant has no video, that's sufficient to say
      // it is audio-only content.
      return !variants[0].video;
    } else if (this.video_ && this.video_.src) {
      // If we have video track info, use that.  It will be the least
      // error-prone way with native HLS.  In contrast, videoHeight might be
      // unset until the first frame is loaded.  Since isAudioOnly is queried
      // by the UI on the 'trackschanged' event, the videoTracks info should be
      // up-to-date.
      if (this.video_.videoTracks) {
        return this.video_.videoTracks.length == 0;
      }

      // We cast to the more specific HTMLVideoElement to access videoHeight.
      // This might be an audio element, though, in which case videoHeight will
      // be undefined at runtime.  For audio elements, this will always return
      // true.
      const video = /** @type {HTMLVideoElement} */(this.video_);
      return video.videoHeight == 0;
    } else {
      return false;
    }
  }

  /**
   * Get the range of time (in seconds) that seeking is allowed. If the player
   * has not loaded content and the manifest is HLS, this will return a range
   * from 0 to 0.
   *
   * @return {{start: number, end: number}}
   * @export
   */
  seekRange() {
    if (this.manifest_) {
      // With HLS lazy-loading, there were some situations where the manifest
      // had partially loaded, enough to move onto further load stages, but no
      // segments had been loaded, so the timeline is still unknown.
      // See: https://github.com/shaka-project/shaka-player/pull/4590
      if (!this.fullyLoaded_ &&
          this.manifest_.type == shaka.media.ManifestParser.HLS) {
        return {'start': 0, 'end': 0};
      }
      const timeline = this.manifest_.presentationTimeline;

      return {
        'start': timeline.getSeekRangeStart(),
        'end': timeline.getSeekRangeEnd(),
      };
    }

    // If we have loaded content with src=, we ask the video element for its
    // seekable range.  This covers both plain mp4s and native HLS playbacks.
    if (this.video_ && this.video_.src) {
      const seekable = this.video_.seekable;
      if (seekable.length) {
        return {
          'start': seekable.start(0),
          'end': seekable.end(seekable.length - 1),
        };
      }
    }

    return {'start': 0, 'end': 0};
  }

  /**
   * Go to live in a live stream.
   *
   * @export
   */
  goToLive() {
    if (this.isLive()) {
      this.video_.currentTime = this.seekRange().end;
    } else {
      shaka.log.warning('goToLive is for live streams!');
    }
  }

  /**
   * Get the key system currently used by EME. If EME is not being used, this
   * will return an empty string. If the player has not loaded content, this
   * will return an empty string.
   *
   * @return {string}
   * @export
   */
  keySystem() {
    return shaka.media.DrmEngine.keySystem(this.drmInfo());
  }

  /**
   * Get the drm info used to initialize EME. If EME is not being used, this
   * will return <code>null</code>. If the player is idle or has not initialized
   * EME yet, this will return <code>null</code>.
   *
   * @return {?shaka.extern.DrmInfo}
   * @export
   */
  drmInfo() {
    return this.drmEngine_ ? this.drmEngine_.getDrmInfo() : null;
  }


  /**
   * Get the drm engine.
   * This method should only be used for testing. Applications SHOULD NOT
   * use this in production.
   *
   * @return {?shaka.media.DrmEngine}
   */
  getDrmEngine() {
    return this.drmEngine_;
  }


  /**
   * Get the next known expiration time for any EME session. If the session
   * never expires, this will return <code>Infinity</code>. If there are no EME
   * sessions, this will return <code>Infinity</code>. If the player has not
   * loaded content, this will return <code>Infinity</code>.
   *
   * @return {number}
   * @export
   */
  getExpiration() {
    return this.drmEngine_ ? this.drmEngine_.getExpiration() : Infinity;
  }

  /**
   * Returns the active sessions metadata
   *
   * @return {!Array.<shaka.extern.DrmSessionMetadata>}
   * @export
   */
  getActiveSessionsMetadata() {
    return this.drmEngine_ ? this.drmEngine_.getActiveSessionsMetadata() : [];
  }

  /**
   * Gets a map of EME key ID to the current key status.
   *
   * @return {!Object<string, string>}
   * @export
   */
  getKeyStatuses() {
    return this.drmEngine_ ? this.drmEngine_.getKeyStatuses() : {};
  }

  /**
   * Check if the player is currently in a buffering state (has too little
   * content to play smoothly). If the player has not loaded content, this will
   * return <code>false</code>.
   *
   * @return {boolean}
   * @export
   */
  isBuffering() {
    const State = shaka.media.BufferingObserver.State;
    return this.bufferObserver_ ?
           this.bufferObserver_.getState() == State.STARVING :
           false;
  }

  /**
   * Get the playback rate of what is playing right now. If we are using trick
   * play, this will return the trick play rate.
   * If no content is playing, this will return 0.
   * If content is buffering, this will return the expected playback rate once
   * the video starts playing.
   *
   * <p>
   * If the player has not loaded content, this will return a playback rate of
   * 0.
   *
   * @return {number}
   * @export
   */
  getPlaybackRate() {
    if (!this.video_) {
      return 0;
    }
    return this.playRateController_ ?
           this.playRateController_.getRealRate() :
           1;
  }

  /**
   * Enable trick play to skip through content without playing by repeatedly
   * seeking. For example, a rate of 2.5 would result in 2.5 seconds of content
   * being skipped every second. A negative rate will result in moving
   * backwards.
   *
   * <p>
   * If the player has not loaded content or is still loading content this will
   * be a no-op. Wait until <code>load</code> has completed before calling.
   *
   * <p>
   * Trick play will be canceled automatically if the playhead hits the
   * beginning or end of the seekable range for the content.
   *
   * @param {number} rate
   * @export
   */
  trickPlay(rate) {
    // A playbackRate of 0 is used internally when we are in a buffering state,
    // and doesn't make sense for trick play.  If you set a rate of 0 for trick
    // play, we will reject it and issue a warning.  If it happens during a
    // test, we will fail the test through this assertion.
    goog.asserts.assert(rate != 0, 'Should never set a trick play rate of 0!');
    if (rate == 0) {
      shaka.log.alwaysWarn('A trick play rate of 0 is unsupported!');
      return;
    }
    this.trickPlayEventManager_.removeAll();

    if (this.video_.paused) {
      // Our fast forward is implemented with playbackRate and needs the video
      // to be playing (to not be paused) to take immediate effect.
      // If the video is paused, "unpause" it.
      this.video_.play();
    }
    this.playRateController_.set(rate);

    if (this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE) {
      this.abrManager_.playbackRateChanged(rate);
      this.streamingEngine_.setTrickPlay(Math.abs(rate) > 1);
    }
    if (this.isLive()) {
      this.trickPlayEventManager_.listen(this.video_, 'timeupdate', () => {
        const currentTime = this.video_.currentTime;
        const seekRange = this.seekRange();
        const safeSeekOffset = this.config_.streaming.safeSeekOffset;

        // Cancel trick play if we hit the beginning or end of the seekable
        // (Sub-second accuracy not required here)
        if (rate > 0) {
          if (Math.floor(currentTime) >= Math.floor(seekRange.end)) {
            this.cancelTrickPlay();
          }
        } else {
          if (Math.floor(currentTime) <=
              Math.floor(seekRange.start + safeSeekOffset)) {
            this.cancelTrickPlay();
          }
        }
      });
    }
  }

  /**
   * Cancel trick-play. If the player has not loaded content or is still loading
   * content this will be a no-op.
   *
   * @export
   */
  cancelTrickPlay() {
    const defaultPlaybackRate = this.playRateController_.getDefaultRate();
    if (this.loadMode_ == shaka.Player.LoadMode.SRC_EQUALS) {
      this.playRateController_.set(defaultPlaybackRate);
    }

    if (this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE) {
      this.playRateController_.set(defaultPlaybackRate);
      this.abrManager_.playbackRateChanged(defaultPlaybackRate);
      this.streamingEngine_.setTrickPlay(false);
    }
    this.trickPlayEventManager_.removeAll();
  }

  /**
   * Return a list of variant tracks that can be switched to.
   *
   * <p>
   * If the player has not loaded content, this will return an empty list.
   *
   * @return {!Array.<shaka.extern.Track>}
   * @export
   */
  getVariantTracks() {
    if (this.manifest_) {
      const currentVariant = this.streamingEngine_ ?
          this.streamingEngine_.getCurrentVariant() : null;

      const tracks = [];

      let activeTracks = 0;

      // Convert each variant to a track.
      for (const variant of this.manifest_.variants) {
        if (!shaka.util.StreamUtils.isPlayable(variant)) {
          continue;
        }

        const track = shaka.util.StreamUtils.variantToTrack(variant);
        track.active = variant == currentVariant;
        if (!track.active && activeTracks != 1 && currentVariant != null &&
          variant.video == currentVariant.video &&
          variant.audio == currentVariant.audio) {
          track.active = true;
        }

        if (track.active) {
          activeTracks++;
        }

        tracks.push(track);
      }

      goog.asserts.assert(activeTracks <= 1,
          'It should only have one active track');

      return tracks;
    } else if (this.video_ && this.video_.audioTracks) {
      // Safari's native HLS always shows a single element in videoTracks.
      // You can't use that API to change resolutions.  But we can use
      // audioTracks to generate a variant list that is usable for changing
      // languages.
      const audioTracks = Array.from(this.video_.audioTracks);
      return audioTracks.map((audio) =>
        shaka.util.StreamUtils.html5AudioTrackToTrack(audio));
    } else {
      return [];
    }
  }

  /**
   * Return a list of text tracks that can be switched to.
   *
   * <p>
   * If the player has not loaded content, this will return an empty list.
   *
   * @return {!Array.<shaka.extern.Track>}
   * @export
   */
  getTextTracks() {
    if (this.manifest_) {
      const currentTextStream = this.streamingEngine_ ?
          this.streamingEngine_.getCurrentTextStream() : null;
      const tracks = [];

      // Convert all selectable text streams to tracks.
      for (const text of this.manifest_.textStreams) {
        const track = shaka.util.StreamUtils.textStreamToTrack(text);
        track.active = text == currentTextStream;

        tracks.push(track);
      }

      return tracks;
    } else if (this.video_ && this.video_.src && this.video_.textTracks) {
      const textTracks = this.getFilteredTextTracks_();
      const StreamUtils = shaka.util.StreamUtils;
      return textTracks.map((text) => StreamUtils.html5TextTrackToTrack(text));
    } else {
      return [];
    }
  }

  /**
   * Return a list of image tracks that can be switched to.
   *
   * If the player has not loaded content, this will return an empty list.
   *
   * @return {!Array.<shaka.extern.Track>}
   * @export
   */
  getImageTracks() {
    const StreamUtils = shaka.util.StreamUtils;
    let imageStreams = this.externalSrcEqualsThumbnailsStreams_;
    if (this.manifest_) {
      imageStreams = this.manifest_.imageStreams;
    }
    return imageStreams.map((image) => StreamUtils.imageStreamToTrack(image));
  }

  /**
   * Returns Thumbnail objects for each thumbnail for a given image track ID.
   *
   * If the player has not loaded content, this will return a null.
   *
   * @param {number} trackId
   * @return {!Promise.<?Array<!shaka.extern.Thumbnail>>}
   * @export
   */
  async getAllThumbnails(trackId) {
    if (this.loadMode_ != shaka.Player.LoadMode.MEDIA_SOURCE &&
        this.loadMode_ != shaka.Player.LoadMode.SRC_EQUALS) {
      return null;
    }
    let imageStreams = this.externalSrcEqualsThumbnailsStreams_;
    if (this.manifest_) {
      imageStreams = this.manifest_.imageStreams;
    }
    const imageStream = imageStreams.find(
        (stream) => stream.id == trackId);
    if (!imageStream) {
      return null;
    }
    if (!imageStream.segmentIndex) {
      await imageStream.createSegmentIndex();
    }
    const promises = [];
    imageStream.segmentIndex.forEachTopLevelReference((reference) => {
      const dimensions = this.parseTilesLayout_(
          reference.getTilesLayout() || imageStream.tilesLayout);
      if (dimensions) {
        const numThumbnails = dimensions.rows * dimensions.columns;
        const duration = reference.trueEndTime - reference.startTime;
        for (let i = 0; i < numThumbnails; i++) {
          const sampleTime = reference.startTime + duration * i / numThumbnails;
          promises.push(this.getThumbnails(trackId, sampleTime));
        }
      }
    });
    const thumbnails = await Promise.all(promises);
    return thumbnails.filter((t) => t);
  }

  /**
   * Parses a tiles layout.
   *
   * @param {string|undefined} tilesLayout
   * @return {?{
   *   columns: number,
   *   rows: number
   * }}
   * @private
   */
  parseTilesLayout_(tilesLayout) {
    if (!tilesLayout) {
      return null;
    }
    // This expression is used to detect one or more numbers (0-9) followed
    // by an x and after one or more numbers (0-9)
    const match = /(\d+)x(\d+)/.exec(tilesLayout);
    if (!match) {
      shaka.log.warning('Tiles layout does not contain a valid format ' +
          ' (columns x rows)');
      return null;
    }
    const columns = parseInt(match[1], 10);
    const rows = parseInt(match[2], 10);
    return {columns, rows};
  }

  /**
   * Return a Thumbnail object from a image track Id and time.
   *
   * If the player has not loaded content, this will return a null.
   *
   * @param {number} trackId
   * @param {number} time
   * @return {!Promise.<?shaka.extern.Thumbnail>}
   * @export
   */
  async getThumbnails(trackId, time) {
    if (this.loadMode_ != shaka.Player.LoadMode.MEDIA_SOURCE &&
        this.loadMode_ != shaka.Player.LoadMode.SRC_EQUALS) {
      return null;
    }
    let imageStreams = this.externalSrcEqualsThumbnailsStreams_;
    if (this.manifest_) {
      imageStreams = this.manifest_.imageStreams;
    }
    const imageStream = imageStreams.find(
        (stream) => stream.id == trackId);
    if (!imageStream) {
      return null;
    }
    if (!imageStream.segmentIndex) {
      await imageStream.createSegmentIndex();
    }
    const referencePosition = imageStream.segmentIndex.find(time);
    if (referencePosition == null) {
      return null;
    }
    const reference = imageStream.segmentIndex.get(referencePosition);
    const dimensions = this.parseTilesLayout_(
        reference.getTilesLayout() || imageStream.tilesLayout);
    if (!dimensions) {
      return null;
    }
    const fullImageWidth = imageStream.width || 0;
    const fullImageHeight = imageStream.height || 0;
    let width = fullImageWidth / dimensions.columns;
    let height = fullImageHeight / dimensions.rows;
    const totalImages = dimensions.columns * dimensions.rows;
    const segmentDuration = reference.trueEndTime - reference.startTime;
    const thumbnailDuration =
        reference.getTileDuration() || (segmentDuration / totalImages);
    let thumbnailTime = reference.startTime;
    let positionX = 0;
    let positionY = 0;
    // If the number of images in the segment is greater than 1, we have to
    // find the correct image. For that we will return to the app the
    // coordinates of the position of the correct image.
    // Image search is always from left to right and top to bottom.
    // Note: The time between images within the segment is always
    // equidistant.
    //
    // Eg: Total images 5, tileLayout 5x1, segmentDuration 5, thumbnailTime 2
    // positionX = 0.4 * fullImageWidth
    // positionY = 0
    if (totalImages > 1) {
      const thumbnailPosition =
          Math.floor((time - reference.startTime) / thumbnailDuration);
      thumbnailTime = reference.startTime +
          (thumbnailPosition * thumbnailDuration);
      positionX = (thumbnailPosition % dimensions.columns) * width;
      positionY = Math.floor(thumbnailPosition / dimensions.columns) * height;
    }
    let sprite = false;
    const thumbnailSprite = reference.getThumbnailSprite();
    if (thumbnailSprite) {
      sprite = true;
      height = thumbnailSprite.height;
      positionX = thumbnailSprite.positionX;
      positionY = thumbnailSprite.positionY;
      width = thumbnailSprite.width;
    }
    return {
      segment: reference,
      imageHeight: fullImageHeight,
      imageWidth: fullImageWidth,
      height: height,
      positionX: positionX,
      positionY: positionY,
      startTime: thumbnailTime,
      duration: thumbnailDuration,
      uris: reference.getUris(),
      width: width,
      sprite: sprite,
    };
  }

  /**
   * Select a specific text track. <code>track</code> should come from a call to
   * <code>getTextTracks</code>. If the track is not found, this will be a
   * no-op. If the player has not loaded content, this will be a no-op.
   *
   * <p>
   * Note that <code>AdaptationEvents</code> are not fired for manual track
   * selections.
   *
   * @param {shaka.extern.Track} track
   * @export
   */
  selectTextTrack(track) {
    if (this.manifest_ && this.streamingEngine_) {
      const stream = this.manifest_.textStreams.find(
          (stream) => stream.id == track.id);

      if (!stream) {
        shaka.log.error('No stream with id', track.id);
        return;
      }

      if (stream == this.streamingEngine_.getCurrentTextStream()) {
        shaka.log.debug('Text track already selected.');
        return;
      }

      // Add entries to the history.
      this.addTextStreamToSwitchHistory_(stream, /* fromAdaptation= */ false);
      this.streamingEngine_.switchTextStream(stream);
      this.onTextChanged_();

      // Workaround for
      // https://github.com/shaka-project/shaka-player/issues/1299
      // When track is selected, back-propagate the language to
      // currentTextLanguage_.
      this.currentTextLanguage_ = stream.language;
    } else if (this.video_ && this.video_.src && this.video_.textTracks) {
      const textTracks = this.getFilteredTextTracks_();
      for (const textTrack of textTracks) {
        if (shaka.util.StreamUtils.html5TrackId(textTrack) == track.id) {
          // Leave the track in 'hidden' if it's selected but not showing.
          textTrack.mode = this.isTextVisible_ ? 'showing' : 'hidden';
        } else {
          // Safari allows multiple text tracks to have mode == 'showing', so be
          // explicit in resetting the others.
          textTrack.mode = 'disabled';
        }
      }
      this.onTextChanged_();
    }
  }

  /**
   * Select a specific variant track to play.  <code>track</code> should come
   * from a call to <code>getVariantTracks</code>. If <code>track</code> cannot
   * be found, this will be a no-op. If the player has not loaded content, this
   * will be a no-op.
   *
   * <p>
   * Changing variants will take effect once the currently buffered content has
   * been played. To force the change to happen sooner, use
   * <code>clearBuffer</code> with <code>safeMargin</code>. Setting
   * <code>clearBuffer</code> to <code>true</code> will clear all buffered
   * content after <code>safeMargin</code>, allowing the new variant to start
   * playing sooner.
   *
   * <p>
   * Note that <code>AdaptationEvents</code> are not fired for manual track
   * selections.
   *
   * @param {shaka.extern.Track} track
   * @param {boolean=} clearBuffer
   * @param {number=} safeMargin Optional amount of buffer (in seconds) to
   *   retain when clearing the buffer. Useful for switching variant quickly
   *   without causing a buffering event. Defaults to 0 if not provided. Ignored
   *   if clearBuffer is false. Can cause hiccups on some browsers if chosen too
   *   small, e.g. The amount of two segments is a fair minimum to consider as
   *   safeMargin value.
   * @export
   */
  selectVariantTrack(track, clearBuffer = false, safeMargin = 0) {
    if (this.manifest_ && this.streamingEngine_) {
      if (this.config_.abr.enabled) {
        shaka.log.alwaysWarn('Changing tracks while abr manager is enabled ' +
                             'will likely result in the selected track ' +
                             'being overriden. Consider disabling abr before ' +
                             'calling selectVariantTrack().');
      }

      const variant = this.manifest_.variants.find(
          (variant) => variant.id == track.id);
      if (!variant) {
        shaka.log.error('No variant with id', track.id);
        return;
      }

      // Double check that the track is allowed to be played. The track list
      // should only contain playable variants, but if restrictions change and
      // |selectVariantTrack| is called before the track list is updated, we
      // could get a now-restricted variant.
      if (!shaka.util.StreamUtils.isPlayable(variant)) {
        shaka.log.error('Unable to switch to restricted track', track.id);
        return;
      }

      this.switchVariant_(
          variant, /* fromAdaptation= */ false, clearBuffer, safeMargin);

      // Workaround for
      // https://github.com/shaka-project/shaka-player/issues/1299
      // When track is selected, back-propagate the language to
      // currentAudioLanguage_.
      this.currentAdaptationSetCriteria_ = new shaka.media.ExampleBasedCriteria(
          variant,
          this.config_.mediaSource.codecSwitchingStrategy,
          this.config_.manifest.dash.enableAudioGroups);

      // Update AbrManager variants to match these new settings.
      this.updateAbrManagerVariants_();
    } else if (this.video_ && this.video_.audioTracks) {
      // Safari's native HLS won't let you choose an explicit variant, though
      // you can choose audio languages this way.
      const audioTracks = Array.from(this.video_.audioTracks);
      for (const audioTrack of audioTracks) {
        if (shaka.util.StreamUtils.html5TrackId(audioTrack) == track.id) {
          // This will reset the "enabled" of other tracks to false.
          this.switchHtml5Track_(audioTrack);
          return;
        }
      }
    }
  }

  /**
   * Return a list of audio language-role combinations available.  If the
   * player has not loaded any content, this will return an empty list.
   *
   * @return {!Array.<shaka.extern.LanguageRole>}
   * @export
   */
  getAudioLanguagesAndRoles() {
    return shaka.Player.getLanguageAndRolesFrom_(this.getVariantTracks());
  }

  /**
   * Return a list of text language-role combinations available.  If the player
   * has not loaded any content, this will be return an empty list.
   *
   * @return {!Array.<shaka.extern.LanguageRole>}
   * @export
   */
  getTextLanguagesAndRoles() {
    return shaka.Player.getLanguageAndRolesFrom_(this.getTextTracks());
  }

  /**
   * Return a list of audio languages available. If the player has not loaded
   * any content, this will return an empty list.
   *
   * @return {!Array.<string>}
   * @export
   */
  getAudioLanguages() {
    return Array.from(shaka.Player.getLanguagesFrom_(this.getVariantTracks()));
  }

  /**
   * Return a list of text languages available. If the player has not loaded
   * any content, this will return an empty list.
   *
   * @return {!Array.<string>}
   * @export
   */
  getTextLanguages() {
    return Array.from(shaka.Player.getLanguagesFrom_(this.getTextTracks()));
  }

  /**
   * Sets the current audio language and current variant role to the selected
   * language, role and channel count, and chooses a new variant if need be.
   * If the player has not loaded any content, this will be a no-op.
   *
   * @param {string} language
   * @param {string=} role
   * @param {number=} channelsCount
   * @param {number=} safeMargin
   * @export
   */
  selectAudioLanguage(language, role, channelsCount = 0, safeMargin = 0) {
    if (this.manifest_ && this.playhead_) {
      this.currentAdaptationSetCriteria_ =
          new shaka.media.PreferenceBasedCriteria(
              language,
              role || '',
              channelsCount,
              /* hdrLevel= */ '',
              /* spatialAudio= */ false,
              /* videoLayout= */ '',
              /* audioLabel= */ '',
              /* videoLabel= */ '',
              this.config_.mediaSource.codecSwitchingStrategy,
              this.config_.manifest.dash.enableAudioGroups);

      const diff = (a, b) => {
        if (!a.video && !b.video) {
          return 0;
        } else if (!a.video || !b.video) {
          return Infinity;
        } else {
          return Math.abs((a.video.height || 0) - (b.video.height || 0)) +
                Math.abs((a.video.width || 0) - (b.video.width || 0));
        }
      };
        // Find the variant whose size is closest to the active variant.  This
        // ensures we stay at about the same resolution when just changing the
        // language/role.
      const active = this.streamingEngine_.getCurrentVariant();
      const set =
            this.currentAdaptationSetCriteria_.create(this.manifest_.variants);
      let bestVariant = null;
      for (const curVariant of set.values()) {
        if (!bestVariant ||
              diff(bestVariant, active) > diff(curVariant, active)) {
          bestVariant = curVariant;
        }
      }
      if (bestVariant) {
        const track = shaka.util.StreamUtils.variantToTrack(bestVariant);
        this.selectVariantTrack(track, /* clearBuffer= */ true, safeMargin);
        return;
      }

      // If we haven't switched yet, just use ABR to find a new track.
      this.chooseVariantAndSwitch_();
    } else if (this.video_ && this.video_.audioTracks) {
      const track = shaka.util.StreamUtils.filterStreamsByLanguageAndRole(
          this.getVariantTracks(), language, role || '', false)[0];
      if (track) {
        this.selectVariantTrack(track);
      }
    }
  }

  /**
   * Sets the current text language and current text role to the selected
   * language and role, and chooses a new variant if need be. If the player has
   * not loaded any content, this will be a no-op.
   *
   * @param {string} language
   * @param {string=} role
   * @param {boolean=} forced
   * @export
   */
  selectTextLanguage(language, role, forced = false) {
    if (this.manifest_ && this.playhead_) {
      this.currentTextLanguage_ = language;
      this.currentTextRole_ = role || '';
      this.currentTextForced_ = forced;

      const chosenText = this.chooseTextStream_();
      if (chosenText) {
        if (chosenText == this.streamingEngine_.getCurrentTextStream()) {
          shaka.log.debug('Text track already selected.');
          return;
        }

        this.addTextStreamToSwitchHistory_(
            chosenText, /* fromAdaptation= */ false);
        if (this.shouldStreamText_()) {
          this.streamingEngine_.switchTextStream(chosenText);
          this.onTextChanged_();
        }
      }
    } else {
      const track = shaka.util.StreamUtils.filterStreamsByLanguageAndRole(
          this.getTextTracks(), language, role || '', forced)[0];
      if (track) {
        this.selectTextTrack(track);
      }
    }
  }

  /**
   * Select variant tracks that have a given label. This assumes the
   * label uniquely identifies an audio stream, so all the variants
   * are expected to have the same variant.audio.
   *
   * @param {string} label
   * @param {boolean=} clearBuffer Optional clear buffer or not when
   *  switch to new variant
   *  Defaults to true if not provided
   * @param {number=} safeMargin Optional amount of buffer (in seconds) to
   *   retain when clearing the buffer.
   *   Defaults to 0 if not provided. Ignored if clearBuffer is false.
   * @export
   */
  selectVariantsByLabel(label, clearBuffer = true, safeMargin = 0) {
    if (this.manifest_ && this.playhead_) {
      let firstVariantWithLabel = null;
      for (const variant of this.manifest_.variants) {
        if (variant.audio.label == label) {
          firstVariantWithLabel = variant;
          break;
        }
      }

      if (firstVariantWithLabel == null) {
        shaka.log.warning('No variants were found with label: ' +
            label + '. Ignoring the request to switch.');

        return;
      }

      // Label is a unique identifier of a variant's audio stream.
      // Because of that we assume that all the variants with the same
      // label have the same language.
      this.currentAdaptationSetCriteria_ =
          new shaka.media.PreferenceBasedCriteria(
              firstVariantWithLabel.language,
              /* role= */ '',
              /* channelCount= */ 0,
              /* hdrLevel= */ '',
              /* spatialAudio= */ false,
              /* videoLayout= */ '',
              label,
              /* videoLabel= */ '',
              this.config_.mediaSource.codecSwitchingStrategy,
              this.config_.manifest.dash.enableAudioGroups);

      this.chooseVariantAndSwitch_(clearBuffer, safeMargin);
    } else if (this.video_ && this.video_.audioTracks) {
      const audioTracks = Array.from(this.video_.audioTracks);

      let trackMatch = null;

      for (const audioTrack of audioTracks) {
        if (audioTrack.label == label) {
          trackMatch = audioTrack;
        }
      }
      if (trackMatch) {
        this.switchHtml5Track_(trackMatch);
      }
    }
  }

  /**
   * Check if the text displayer is enabled.
   *
   * @return {boolean}
   * @export
   */
  isTextTrackVisible() {
    const expected = this.isTextVisible_;

    if (this.mediaSourceEngine_ &&
        this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE) {
      // Make sure our values are still in-sync.
      const actual = this.mediaSourceEngine_.getTextDisplayer().isTextVisible();
      goog.asserts.assert(
          actual == expected, 'text visibility has fallen out of sync');

      // Always return the actual value so that the app has the most accurate
      // information (in the case that the values come out of sync in prod).
      return actual;
    } else if (this.video_ && this.video_.src && this.video_.textTracks) {
      const textTracks = this.getFilteredTextTracks_();
      return textTracks.some((t) => t.mode == 'showing');
    }

    return expected;
  }

  /**
   * Return a list of chapters tracks.
   *
   * @return {!Array.<shaka.extern.Track>}
   * @export
   */
  getChaptersTracks() {
    if (this.video_ && this.video_.src && this.video_.textTracks) {
      const textTracks = this.getChaptersTracks_();
      const StreamUtils = shaka.util.StreamUtils;
      return textTracks.map((text) => StreamUtils.html5TextTrackToTrack(text));
    } else {
      return [];
    }
  }

  /**
   * This returns the list of chapters.
   *
   * @param {string} language
   * @return {!Array.<shaka.extern.Chapter>}
   * @export
   */
  getChapters(language) {
    if (!this.video_ || !this.video_.src || !this.video_.textTracks) {
      return [];
    }
    const LanguageUtils = shaka.util.LanguageUtils;
    const inputlanguage = LanguageUtils.normalize(language);
    const chaptersTracks = this.getChaptersTracks_();
    const chaptersTracksWithLanguage = chaptersTracks
        .filter((t) => LanguageUtils.normalize(t.language) == inputlanguage);
    if (!chaptersTracksWithLanguage || !chaptersTracksWithLanguage.length) {
      return [];
    }
    const chapters = [];
    const uniqueChapters = new Set();
    for (const chaptersTrack of chaptersTracksWithLanguage) {
      if (chaptersTrack && chaptersTrack.cues) {
        for (const cue of chaptersTrack.cues) {
          let id = cue.id;
          if (!id || id == '') {
            id = cue.startTime + '-' + cue.endTime + '-' + cue.text;
          }
          /** @type {shaka.extern.Chapter} */
          const chapter = {
            id: id,
            title: cue.text,
            startTime: cue.startTime,
            endTime: cue.endTime,
          };
          if (!uniqueChapters.has(id)) {
            chapters.push(chapter);
            uniqueChapters.add(id);
          }
        }
      }
    }
    return chapters;
  }

  /**
   * Ignore the TextTracks with the 'metadata' or 'chapters' kind, or the one
   * generated by the SimpleTextDisplayer.
   *
   * @return {!Array.<TextTrack>}
   * @private
   */
  getFilteredTextTracks_() {
    goog.asserts.assert(this.video_.textTracks,
        'TextTracks should be valid.');
    return Array.from(this.video_.textTracks)
        .filter((t) => t.kind != 'metadata' && t.kind != 'chapters' &&
                       t.label != shaka.Player.TextTrackLabel);
  }

  /**
   * Get the TextTracks with the 'metadata' kind.
   *
   * @return {!Array.<TextTrack>}
   * @private
   */
  getMetadataTracks_() {
    goog.asserts.assert(this.video_.textTracks,
        'TextTracks should be valid.');
    return Array.from(this.video_.textTracks)
        .filter((t) => t.kind == 'metadata');
  }

  /**
   * Get the TextTracks with the 'chapters' kind.
   *
   * @return {!Array.<TextTrack>}
   * @private
   */
  getChaptersTracks_() {
    goog.asserts.assert(this.video_.textTracks,
        'TextTracks should be valid.');
    return Array.from(this.video_.textTracks)
        .filter((t) => t.kind == 'chapters');
  }

  /**
   * Enable or disable the text displayer.  If the player is in an unloaded
   * state, the request will be applied next time content is loaded.
   *
   * @param {boolean} isVisible
   * @export
   */
  setTextTrackVisibility(isVisible) {
    const oldVisibilty = this.isTextVisible_;
    // Convert to boolean in case apps pass 0/1 instead false/true.
    const newVisibility = !!isVisible;

    if (oldVisibilty == newVisibility) {
      return;
    }

    this.isTextVisible_ = newVisibility;

    // Hold of on setting the text visibility until we have all the components
    // we need. This ensures that they stay in-sync.
    if (this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE) {
      this.mediaSourceEngine_.getTextDisplayer()
          .setTextVisibility(newVisibility);

      // When the user wants to see captions, we stream captions. When the user
      // doesn't want to see captions, we don't stream captions. This is to
      // avoid bandwidth consumption by an unused resource. The app developer
      // can override this and configure us to always stream captions.
      if (!this.config_.streaming.alwaysStreamText) {
        if (newVisibility) {
          if (this.streamingEngine_.getCurrentTextStream()) {
            // We already have a selected text stream.
          } else {
            // Find the text stream that best matches the user's preferences.
            const streams =
                shaka.util.StreamUtils.filterStreamsByLanguageAndRole(
                    this.manifest_.textStreams,
                    this.currentTextLanguage_,
                    this.currentTextRole_,
                    this.currentTextForced_);

            // It is possible that there are no streams to play.
            if (streams.length > 0) {
              this.streamingEngine_.switchTextStream(streams[0]);
              this.onTextChanged_();
            }
          }
        } else {
          this.streamingEngine_.unloadTextStream();
        }
      }
    } else if (this.video_ && this.video_.src && this.video_.textTracks) {
      const textTracks = this.getFilteredTextTracks_();
      // Find the active track by looking for one which is not disabled.  This
      // is the only way to identify the track which is currently displayed.
      // Set it to 'showing' or 'hidden' based on newVisibility.
      for (const textTrack of textTracks) {
        if (textTrack.mode != 'disabled') {
          textTrack.mode = newVisibility ? 'showing' : 'hidden';
        }
      }
    }

    // We need to fire the event after we have updated everything so that
    // everything will be in a stable state when the app responds to the
    // event.
    this.onTextTrackVisibility_();
  }

  /**
   * Get the current playhead position as a date.
   *
   * @return {Date}
   * @export
   */
  getPlayheadTimeAsDate() {
    let presentationTime = 0;
    if (this.playhead_) {
      presentationTime = this.playhead_.getTime();
    } else if (this.startTime_ == null) {
      // A live stream with no requested start time and no playhead yet.  We
      // would start at the live edge, but we don't have that yet, so return
      // the current date & time.
      return new Date();
    } else {
      // A specific start time has been requested.  This is what Playhead will
      // use once it is created.
      presentationTime = this.startTime_;
    }

    if (this.manifest_) {
      const timeline = this.manifest_.presentationTimeline;
      const startTime = timeline.getInitialProgramDateTime() ||
          timeline.getPresentationStartTime();
      return new Date(/* ms= */ (startTime + presentationTime) * 1000);
    } else if (this.video_ && this.video_.getStartDate) {
      // Apple's native HLS gives us getStartDate(), which is only available if
      // EXT-X-PROGRAM-DATETIME is in the playlist.
      const startDate = this.video_.getStartDate();
      if (isNaN(startDate.getTime())) {
        shaka.log.warning(
            'EXT-X-PROGRAM-DATETIME required to get playhead time as Date!');
        return null;
      }
      return new Date(startDate.getTime() + (presentationTime * 1000));
    } else {
      shaka.log.warning('No way to get playhead time as Date!');
      return null;
    }
  }

  /**
   * Get the presentation start time as a date.
   *
   * @return {Date}
   * @export
   */
  getPresentationStartTimeAsDate() {
    if (this.manifest_) {
      const timeline = this.manifest_.presentationTimeline;
      const startTime = timeline.getInitialProgramDateTime() ||
          timeline.getPresentationStartTime();
      goog.asserts.assert(startTime != null,
          'Presentation start time should not be null!');
      return new Date(/* ms= */ startTime * 1000);
    } else if (this.video_ && this.video_.getStartDate) {
      // Apple's native HLS gives us getStartDate(), which is only available if
      // EXT-X-PROGRAM-DATETIME is in the playlist.
      const startDate = this.video_.getStartDate();
      if (isNaN(startDate.getTime())) {
        shaka.log.warning(
            'EXT-X-PROGRAM-DATETIME required to get presentation start time ' +
            'as Date!');
        return null;
      }
      return startDate;
    } else {
      shaka.log.warning('No way to get presentation start time as Date!');
      return null;
    }
  }

  /**
   * Get the presentation segment availability duration. This should only be
   * called when the player has loaded a live stream. If the player has not
   * loaded a live stream, this will return <code>null</code>.
   *
   * @return {?number}
   * @export
   */
  getSegmentAvailabilityDuration() {
    if (!this.isLive()) {
      shaka.log.warning('getSegmentAvailabilityDuration is for live streams!');
      return null;
    }

    if (this.manifest_) {
      const timeline = this.manifest_.presentationTimeline;
      return timeline.getSegmentAvailabilityDuration();
    } else {
      shaka.log.warning('No way to get segment segment availability duration!');
      return null;
    }
  }

  /**
   * Get information about what the player has buffered. If the player has not
   * loaded content or is currently loading content, the buffered content will
   * be empty.
   *
   * @return {shaka.extern.BufferedInfo}
   * @export
   */
  getBufferedInfo() {
    if (this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE) {
      return this.mediaSourceEngine_.getBufferedInfo();
    }

    const info = {
      total: [],
      audio: [],
      video: [],
      text: [],
    };

    if (this.loadMode_ == shaka.Player.LoadMode.SRC_EQUALS) {
      const TimeRangesUtils = shaka.media.TimeRangesUtils;
      info.total = TimeRangesUtils.getBufferedInfo(this.video_.buffered);
    }

    return info;
  }

  /**
   * Get statistics for the current playback session. If the player is not
   * playing content, this will return an empty stats object.
   *
   * @return {shaka.extern.Stats}
   * @export
   */
  getStats() {
    // If the Player is not in a fully-loaded state, then return an empty stats
    // blob so that this call will never fail.
    const loaded = this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE ||
                   this.loadMode_ == shaka.Player.LoadMode.SRC_EQUALS;
    if (!loaded) {
      return shaka.util.Stats.getEmptyBlob();
    }

    this.updateStateHistory_();

    goog.asserts.assert(this.video_, 'If we have stats, we should have video_');
    const element = /** @type {!HTMLVideoElement} */ (this.video_);

    const completionRatio = element.currentTime / element.duration;
    if (!isNaN(completionRatio)) {
      this.stats_.setCompletionPercent(Math.round(100 * completionRatio));
    }

    if (this.playhead_) {
      this.stats_.setGapsJumped(this.playhead_.getGapsJumped());
      this.stats_.setStallsDetected(this.playhead_.getStallsDetected());
    }

    if (element.getVideoPlaybackQuality) {
      const info = element.getVideoPlaybackQuality();

      this.stats_.setDroppedFrames(
          Number(info.droppedVideoFrames),
          Number(info.totalVideoFrames));
      this.stats_.setCorruptedFrames(Number(info.corruptedVideoFrames));
    }

    const licenseSeconds =
        this.drmEngine_ ? this.drmEngine_.getLicenseTime() : NaN;
    this.stats_.setLicenseTime(licenseSeconds);

    if (this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE) {
      // Event through we are loaded, it is still possible that we don't have a
      // variant yet because we set the load mode before we select the first
      // variant to stream.
      const variant = this.streamingEngine_.getCurrentVariant();
      const textStream = this.streamingEngine_.getCurrentTextStream();

      if (variant) {
        const rate = this.playRateController_ ?
           this.playRateController_.getRealRate() : 1;
        const variantBandwidth = rate * variant.bandwidth;
        let currentStreamBandwidth = variantBandwidth;
        if (textStream && textStream.bandwidth) {
          currentStreamBandwidth += (rate * textStream.bandwidth);
        }
        this.stats_.setCurrentStreamBandwidth(currentStreamBandwidth);
      }

      if (variant && variant.video) {
        this.stats_.setResolution(
            /* width= */ variant.video.width || NaN,
            /* height= */ variant.video.height || NaN);
      }

      if (this.isLive()) {
        const now = this.getPresentationStartTimeAsDate().valueOf() +
            element.currentTime * 1000;
        const latency = (Date.now() - now) / 1000;
        this.stats_.setLiveLatency(latency);
      }

      if (this.manifest_ && this.manifest_.presentationTimeline) {
        const maxSegmentDuration =
            this.manifest_.presentationTimeline.getMaxSegmentDuration();
        this.stats_.setMaxSegmentDuration(maxSegmentDuration);
      }

      const estimate = this.abrManager_.getBandwidthEstimate();
      this.stats_.setBandwidthEstimate(estimate);
    }

    if (this.loadMode_ == shaka.Player.LoadMode.SRC_EQUALS) {
      this.stats_.setResolution(
          /* width= */ element.videoWidth || NaN,
          /* height= */ element.videoHeight || NaN);
    }

    return this.stats_.getBlob();
  }

  /**
   * Adds the given text track to the loaded manifest.  <code>load()</code> must
   * resolve before calling.  The presentation must have a duration.
   *
   * This returns the created track, which can immediately be selected by the
   * application.  The track will not be automatically selected.
   *
   * @param {string} uri
   * @param {string} language
   * @param {string} kind
   * @param {string=} mimeType
   * @param {string=} codec
   * @param {string=} label
   * @param {boolean=} forced
   * @return {!Promise.<shaka.extern.Track>}
   * @export
   */
  async addTextTrackAsync(uri, language, kind, mimeType, codec, label,
      forced = false) {
    if (this.loadMode_ != shaka.Player.LoadMode.MEDIA_SOURCE &&
        this.loadMode_ != shaka.Player.LoadMode.SRC_EQUALS) {
      shaka.log.error(
          'Must call load() and wait for it to resolve before adding text ' +
          'tracks.');
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.PLAYER,
          shaka.util.Error.Code.CONTENT_NOT_LOADED);
    }

    if (kind != 'subtitles' && kind != 'captions') {
      shaka.log.alwaysWarn(
          'Using a kind value different of `subtitles` or `captions` can ' +
          'cause unwanted issues.');
    }

    if (!mimeType) {
      mimeType = await this.getTextMimetype_(uri);
    }

    let adCuePoints = [];
    if (this.adManager_) {
      adCuePoints = this.adManager_.getCuePoints();
    }

    if (this.loadMode_ == shaka.Player.LoadMode.SRC_EQUALS) {
      if (forced) {
        // See: https://github.com/whatwg/html/issues/4472
        kind = 'forced';
      }
      await this.addSrcTrackElement_(uri, language, kind, mimeType, label || '',
          adCuePoints);

      const LanguageUtils = shaka.util.LanguageUtils;
      const languageNormalized = LanguageUtils.normalize(language);

      const textTracks = this.getTextTracks();
      const srcTrack = textTracks.find((t) => {
        return LanguageUtils.normalize(t.language) == languageNormalized &&
            t.label == (label || '') &&
            t.kind == kind;
      });
      if (srcTrack) {
        this.onTracksChanged_();
        return srcTrack;
      }
      // This should not happen, but there are browser implementations that may
      // not support the Track element.
      shaka.log.error('Cannot add this text when loaded with src=');
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.TEXT,
          shaka.util.Error.Code.CANNOT_ADD_EXTERNAL_TEXT_TO_SRC_EQUALS);
    }

    const ContentType = shaka.util.ManifestParserUtils.ContentType;

    let duration = this.video_.duration;
    if (this.manifest_) {
      duration = this.manifest_.presentationTimeline.getDuration();
    }
    if (duration == Infinity) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.MANIFEST,
          shaka.util.Error.Code.CANNOT_ADD_EXTERNAL_TEXT_TO_LIVE_STREAM);
    }

    if (adCuePoints.length) {
      goog.asserts.assert(
          this.networkingEngine_, 'Need networking engine.');
      const data = await this.getTextData_(uri,
          this.networkingEngine_,
          this.config_.streaming.retryParameters);
      const vvtText = this.convertToWebVTT_(data, mimeType, adCuePoints);
      const blob = new Blob([vvtText], {type: 'text/vtt'});
      uri = shaka.media.MediaSourceEngine.createObjectURL(blob);
      mimeType = 'text/vtt';
    }

    /** @type {shaka.extern.Stream} */
    const stream = {
      id: this.nextExternalStreamId_++,
      originalId: null,
      groupId: null,
      createSegmentIndex: () => Promise.resolve(),
      segmentIndex: shaka.media.SegmentIndex.forSingleSegment(
          /* startTime= */ 0,
          /* duration= */ duration,
          /* uris= */ [uri]),
      mimeType: mimeType || '',
      codecs: codec || '',
      kind: kind,
      encrypted: false,
      drmInfos: [],
      keyIds: new Set(),
      language: language,
      originalLanguage: language,
      label: label || null,
      type: ContentType.TEXT,
      primary: false,
      trickModeVideo: null,
      emsgSchemeIdUris: null,
      roles: [],
      forced: !!forced,
      channelsCount: null,
      audioSamplingRate: null,
      spatialAudio: false,
      closedCaptions: null,
      accessibilityPurpose: null,
      external: true,
      fastSwitching: false,
      fullMimeTypes: new Set([shaka.util.MimeUtils.getFullType(
          mimeType || '', codec || '')]),
    };

    const fullMimeType = shaka.util.MimeUtils.getFullType(
        stream.mimeType, stream.codecs);
    const supported = shaka.text.TextEngine.isTypeSupported(fullMimeType);
    if (!supported) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.TEXT,
          shaka.util.Error.Code.MISSING_TEXT_PLUGIN,
          mimeType);
    }

    this.manifest_.textStreams.push(stream);
    this.onTracksChanged_();
    return shaka.util.StreamUtils.textStreamToTrack(stream);
  }

  /**
   * Adds the given thumbnails track to the loaded manifest.
   * <code>load()</code> must resolve before calling.  The presentation must
   * have a duration.
   *
   * This returns the created track, which can immediately be used by the
   * application.
   *
   * @param {string} uri
   * @param {string=} mimeType
   * @return {!Promise.<shaka.extern.Track>}
   * @export
   */
  async addThumbnailsTrack(uri, mimeType) {
    if (this.loadMode_ != shaka.Player.LoadMode.MEDIA_SOURCE &&
        this.loadMode_ != shaka.Player.LoadMode.SRC_EQUALS) {
      shaka.log.error(
          'Must call load() and wait for it to resolve before adding image ' +
          'tracks.');
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.PLAYER,
          shaka.util.Error.Code.CONTENT_NOT_LOADED);
    }

    if (!mimeType) {
      mimeType = await this.getTextMimetype_(uri);
    }

    if (mimeType != 'text/vtt') {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.TEXT,
          shaka.util.Error.Code.UNSUPPORTED_EXTERNAL_THUMBNAILS_URI,
          uri);
    }

    const ContentType = shaka.util.ManifestParserUtils.ContentType;
    let duration = this.video_.duration;
    if (this.manifest_) {
      duration = this.manifest_.presentationTimeline.getDuration();
    }
    if (duration == Infinity) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.MANIFEST,
          shaka.util.Error.Code.CANNOT_ADD_EXTERNAL_THUMBNAILS_TO_LIVE_STREAM);
    }

    goog.asserts.assert(
        this.networkingEngine_, 'Need networking engine.');
    const buffer = await this.getTextData_(uri,
        this.networkingEngine_,
        this.config_.streaming.retryParameters);

    const factory = shaka.text.TextEngine.findParser(mimeType);
    if (!factory) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.TEXT,
          shaka.util.Error.Code.MISSING_TEXT_PLUGIN,
          mimeType);
    }
    const TextParser = factory();
    const time = {
      periodStart: 0,
      segmentStart: 0,
      segmentEnd: duration,
      vttOffset: 0,
    };
    const data = shaka.util.BufferUtils.toUint8(buffer);
    const cues = TextParser.parseMedia(data, time, uri);

    const references = [];
    for (const cue of cues) {
      let uris = null;
      const getUris = () => {
        if (uris == null) {
          uris = shaka.util.ManifestParserUtils.resolveUris(
              [uri], [cue.payload]);
        }
        return uris || [];
      };
      const reference = new shaka.media.SegmentReference(
          cue.startTime,
          cue.endTime,
          getUris,
          /* startByte= */ 0,
          /* endByte= */ null,
          /* initSegmentReference= */ null,
          /* timestampOffset= */ 0,
          /* appendWindowStart= */ 0,
          /* appendWindowEnd= */ Infinity,
      );
      if (cue.payload.includes('#xywh')) {
        const spriteInfo = cue.payload.split('#xywh=')[1].split(',');
        if (spriteInfo.length === 4) {
          reference.setThumbnailSprite({
            height: parseInt(spriteInfo[3], 10),
            positionX: parseInt(spriteInfo[0], 10),
            positionY: parseInt(spriteInfo[1], 10),
            width: parseInt(spriteInfo[2], 10),
          });
        }
      }
      references.push(reference);
    }

    /** @type {shaka.extern.Stream} */
    const stream = {
      id: this.nextExternalStreamId_++,
      originalId: null,
      groupId: null,
      createSegmentIndex: () => Promise.resolve(),
      segmentIndex: new shaka.media.SegmentIndex(references),
      mimeType: mimeType || '',
      codecs: '',
      kind: '',
      encrypted: false,
      drmInfos: [],
      keyIds: new Set(),
      language: 'und',
      originalLanguage: null,
      label: null,
      type: ContentType.IMAGE,
      primary: false,
      trickModeVideo: null,
      emsgSchemeIdUris: null,
      roles: [],
      forced: false,
      channelsCount: null,
      audioSamplingRate: null,
      spatialAudio: false,
      closedCaptions: null,
      tilesLayout: '1x1',
      accessibilityPurpose: null,
      external: true,
      fastSwitching: false,
      fullMimeTypes: new Set([shaka.util.MimeUtils.getFullType(
          mimeType || '', '')]),
    };

    if (this.loadMode_ == shaka.Player.LoadMode.SRC_EQUALS) {
      this.externalSrcEqualsThumbnailsStreams_.push(stream);
    } else {
      this.manifest_.imageStreams.push(stream);
    }
    this.onTracksChanged_();
    return shaka.util.StreamUtils.imageStreamToTrack(stream);
  }

  /**
   * Adds the given chapters track to the loaded manifest.  <code>load()</code>
   * must resolve before calling.  The presentation must have a duration.
   *
   * This returns the created track.
   *
   * @param {string} uri
   * @param {string} language
   * @param {string=} mimeType
   * @return {!Promise.<shaka.extern.Track>}
   * @export
   */
  async addChaptersTrack(uri, language, mimeType) {
    if (this.loadMode_ != shaka.Player.LoadMode.MEDIA_SOURCE &&
        this.loadMode_ != shaka.Player.LoadMode.SRC_EQUALS) {
      shaka.log.error(
          'Must call load() and wait for it to resolve before adding ' +
          'chapters tracks.');
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.PLAYER,
          shaka.util.Error.Code.CONTENT_NOT_LOADED);
    }

    if (!mimeType) {
      mimeType = await this.getTextMimetype_(uri);
    }

    let adCuePoints = [];
    if (this.adManager_) {
      adCuePoints = this.adManager_.getCuePoints();
    }

    /** @type {!HTMLTrackElement} */
    const trackElement = await this.addSrcTrackElement_(
        uri, language, /* kind= */ 'chapters', mimeType, /* label= */ '',
        adCuePoints);

    const chaptersTracks = this.getChaptersTracks();
    const chaptersTrack = chaptersTracks.find((t) => {
      return t.language == language;
    });

    if (chaptersTrack) {
      await new Promise((resolve, reject) => {
        // The chapter data isn't available until the 'load' event fires, and
        // that won't happen until the chapters track is activated by the
        // activateChaptersTrack_ method.
        this.loadEventManager_.listenOnce(trackElement, 'load', resolve);
        this.loadEventManager_.listenOnce(trackElement, 'error', (event) => {
          reject(new shaka.util.Error(
              shaka.util.Error.Severity.RECOVERABLE,
              shaka.util.Error.Category.TEXT,
              shaka.util.Error.Code.CHAPTERS_TRACK_FAILED));
        });
      });

      this.onTracksChanged_();

      return chaptersTrack;
    }

    // This should not happen, but there are browser implementations that may
    // not support the Track element.
    shaka.log.error('Cannot add this text when loaded with src=');
    throw new shaka.util.Error(
        shaka.util.Error.Severity.RECOVERABLE,
        shaka.util.Error.Category.TEXT,
        shaka.util.Error.Code.CANNOT_ADD_EXTERNAL_TEXT_TO_SRC_EQUALS);
  }

  /**
   * @param {string} uri
   * @return {!Promise.<string>}
   * @private
   */
  async getTextMimetype_(uri) {
    let mimeType;
    try {
      goog.asserts.assert(
          this.networkingEngine_, 'Need networking engine.');
      // eslint-disable-next-line require-atomic-updates
      mimeType = await shaka.net.NetworkingUtils.getMimeType(uri,
          this.networkingEngine_,
          this.config_.streaming.retryParameters);
    } catch (error) {}

    if (mimeType) {
      return mimeType;
    }

    shaka.log.error(
        'The mimeType has not been provided and it could not be deduced ' +
        'from its uri.');
    throw new shaka.util.Error(
        shaka.util.Error.Severity.RECOVERABLE,
        shaka.util.Error.Category.TEXT,
        shaka.util.Error.Code.TEXT_COULD_NOT_GUESS_MIME_TYPE,
        uri);
  }

  /**
   * @param {string} uri
   * @param {string} language
   * @param {string} kind
   * @param {string} mimeType
   * @param {string} label
   * @param {!Array.<!shaka.extern.AdCuePoint>} adCuePoints
   * @return {!Promise.<!HTMLTrackElement>}
   * @private
   */
  async addSrcTrackElement_(uri, language, kind, mimeType, label,
      adCuePoints) {
    if (mimeType != 'text/vtt' || adCuePoints.length) {
      goog.asserts.assert(
          this.networkingEngine_, 'Need networking engine.');
      const data = await this.getTextData_(uri,
          this.networkingEngine_,
          this.config_.streaming.retryParameters);
      const vvtText = this.convertToWebVTT_(data, mimeType, adCuePoints);
      const blob = new Blob([vvtText], {type: 'text/vtt'});
      uri = shaka.media.MediaSourceEngine.createObjectURL(blob);
      mimeType = 'text/vtt';
    }

    const trackElement =
      /** @type {!HTMLTrackElement} */(document.createElement('track'));
    trackElement.src = this.cmcdManager_.appendTextTrackData(uri);
    trackElement.label = label;
    trackElement.kind = kind;
    trackElement.srclang = language;

    // Because we're pulling in the text track file via Javascript, the
    // same-origin policy applies. If you'd like to have a player served
    // from one domain, but the text track served from another, you'll
    // need to enable CORS in order to do so. In addition to enabling CORS
    // on the server serving the text tracks, you will need to add the
    // crossorigin attribute to the video element itself.
    if (!this.video_.getAttribute('crossorigin')) {
      this.video_.setAttribute('crossorigin', 'anonymous');
    }

    this.video_.appendChild(trackElement);
    return trackElement;
  }

  /**
   * @param {string} uri
   * @param {!shaka.net.NetworkingEngine} netEngine
   * @param {shaka.extern.RetryParameters} retryParams
   * @return {!Promise.<BufferSource>}
   * @private
   */
  async getTextData_(uri, netEngine, retryParams) {
    const type = shaka.net.NetworkingEngine.RequestType.SEGMENT;

    const request = shaka.net.NetworkingEngine.makeRequest([uri], retryParams);
    request.method = 'GET';

    this.cmcdManager_.applyTextData(request);

    const response = await netEngine.request(type, request).promise;

    return response.data;
  }


  /**
   * Converts an input string to a WebVTT format string.
   *
   * @param {BufferSource} buffer
   * @param {string} mimeType
   * @param {!Array.<!shaka.extern.AdCuePoint>} adCuePoints
   * @return {string}
   * @private
   */
  convertToWebVTT_(buffer, mimeType, adCuePoints) {
    const factory = shaka.text.TextEngine.findParser(mimeType);
    if (factory) {
      const obj = factory();
      const time = {
        periodStart: 0,
        segmentStart: 0,
        segmentEnd: this.video_.duration,
        vttOffset: 0,
      };
      const data = shaka.util.BufferUtils.toUint8(buffer);
      const cues = obj.parseMedia(data, time, /* uri= */ null);
      return shaka.text.WebVttGenerator.convert(cues, adCuePoints);
    }
    throw new shaka.util.Error(
        shaka.util.Error.Severity.CRITICAL,
        shaka.util.Error.Category.TEXT,
        shaka.util.Error.Code.MISSING_TEXT_PLUGIN,
        mimeType);
  }

  /**
   * Set the maximum resolution that the platform's hardware can handle.
   *
   * @param {number} width
   * @param {number} height
   * @export
   */
  setMaxHardwareResolution(width, height) {
    this.maxHwRes_.width = width;
    this.maxHwRes_.height = height;
  }

  /**
   * Retry streaming after a streaming failure has occurred. When the player has
   * not loaded content or is loading content, this will be a no-op and will
   * return <code>false</code>.
   *
   * <p>
   * If the player has loaded content, and streaming has not seen an error, this
   * will return <code>false</code>.
   *
   * <p>
   * If the player has loaded content, and streaming seen an error, but the
   * could not resume streaming, this will return <code>false</code>.
   *
   * @param {number=} retryDelaySeconds
   * @return {boolean}
   * @export
   */
  retryStreaming(retryDelaySeconds = 0.1) {
    return this.loadMode_ == shaka.Player.LoadMode.MEDIA_SOURCE ?
           this.streamingEngine_.retry(retryDelaySeconds) :
           false;
  }

  /**
   * Get the manifest that the player has loaded. If the player has not loaded
   * any content, this will return <code>null</code>.
   *
   * NOTE: This structure is NOT covered by semantic versioning compatibility
   * guarantees.  It may change at any time!
   *
   * This is marked as deprecated to warn Closure Compiler users at compile-time
   * to avoid using this method.
   *
   * @return {?shaka.extern.Manifest}
   * @export
   * @deprecated
   */
  getManifest() {
    shaka.log.alwaysWarn(
        'Shaka Player\'s internal Manifest structure is NOT covered by ' +
        'semantic versioning compatibility guarantees.  It may change at any ' +
        'time!  Please consider filing a feature request for whatever you ' +
        'use getManifest() for.');
    return this.manifest_;
  }

  /**
   * Get the type of manifest parser that the player is using. If the player has
   * not loaded any content, this will return <code>null</code>.
   *
   * @return {?shaka.extern.ManifestParser.Factory}
   * @export
   */
  getManifestParserFactory() {
    return this.parserFactory_;
  }

  /**
   * @param {shaka.extern.Variant} variant
   * @param {boolean} fromAdaptation
   * @private
   */
  addVariantToSwitchHistory_(variant, fromAdaptation) {
    const switchHistory = this.stats_.getSwitchHistory();
    switchHistory.updateCurrentVariant(variant, fromAdaptation);
  }

  /**
   * @param {shaka.extern.Stream} textStream
   * @param {boolean} fromAdaptation
   * @private
   */
  addTextStreamToSwitchHistory_(textStream, fromAdaptation) {
    const switchHistory = this.stats_.getSwitchHistory();
    switchHistory.updateCurrentText(textStream, fromAdaptation);
  }

  /**
   * @return {shaka.extern.PlayerConfiguration}
   * @private
   */
  defaultConfig_() {
    const config = shaka.util.PlayerConfiguration.createDefault();

    config.streaming.failureCallback = (error) => {
      this.defaultStreamingFailureCallback_(error);
    };

    // Because this.video_ may not be set when the config is built, the default
    // TextDisplay factory must capture a reference to "this".
    config.textDisplayFactory = () => {
      if (this.videoContainer_) {
        const latestConfig = this.getConfiguration();
        return new shaka.text.UITextDisplayer(
            this.video_, this.videoContainer_, latestConfig.textDisplayer);
      } else {
        // eslint-disable-next-line no-restricted-syntax
        if (HTMLMediaElement.prototype.addTextTrack) {
          return new shaka.text.SimpleTextDisplayer(
              this.video_, shaka.Player.TextTrackLabel);
        } else {
          shaka.log.warning('Text tracks are not supported by the ' +
                            'browser, disabling.');
          return new shaka.text.StubTextDisplayer();
        }
      }
    };
    return config;
  }

  /**
   * Set the videoContainer to construct UITextDisplayer.
   * @param {HTMLElement} videoContainer
   * @export
   */
  setVideoContainer(videoContainer) {
    this.videoContainer_ = videoContainer;
  }

  /**
   * @param {!shaka.util.Error} error
   * @private
   */
  defaultStreamingFailureCallback_(error) {
    // For live streams, we retry streaming automatically for certain errors.
    // For VOD streams, all streaming failures are fatal.
    if (!this.isLive()) {
      return;
    }

    let retryDelaySeconds = null;
    if (error.code == shaka.util.Error.Code.BAD_HTTP_STATUS ||
        error.code == shaka.util.Error.Code.HTTP_ERROR) {
      // These errors can be near-instant, so delay a bit before retrying.
      retryDelaySeconds = 1;
    } else if (error.code == shaka.util.Error.Code.TIMEOUT) {
      // We already waited for a timeout, so retry quickly.
      retryDelaySeconds = 0.1;
    }

    if (retryDelaySeconds != null) {
      error.severity = shaka.util.Error.Severity.RECOVERABLE;
      shaka.log.warning('Live streaming error.  Retrying automatically...');
      this.retryStreaming(retryDelaySeconds);
    }
  }

  /**
   * For CEA closed captions embedded in the video streams, create dummy text
   * stream.  This can be safely called again on existing manifests, for
   * manifest updates.
   * @param {!shaka.extern.Manifest} manifest
   * @private
   */
  makeTextStreamsForClosedCaptions_(manifest) {
    const ContentType = shaka.util.ManifestParserUtils.ContentType;
    const TextStreamKind = shaka.util.ManifestParserUtils.TextStreamKind;
    const CEA608_MIME = shaka.util.MimeUtils.CEA608_CLOSED_CAPTION_MIMETYPE;
    const CEA708_MIME = shaka.util.MimeUtils.CEA708_CLOSED_CAPTION_MIMETYPE;

    // A set, to make sure we don't create two text streams for the same video.
    const closedCaptionsSet = new Set();
    for (const textStream of manifest.textStreams) {
      if (textStream.mimeType == CEA608_MIME ||
          textStream.mimeType == CEA708_MIME) {
        // This function might be called on a manifest update, so don't make a
        // new text stream for closed caption streams we have seen before.
        closedCaptionsSet.add(textStream.originalId);
      }
    }
    for (const variant of manifest.variants) {
      const video = variant.video;
      if (video && video.closedCaptions) {
        for (const id of video.closedCaptions.keys()) {
          if (!closedCaptionsSet.has(id)) {
            const mimeType = id.startsWith('CC') ? CEA608_MIME : CEA708_MIME;

            // Add an empty segmentIndex, for the benefit of the period combiner
            // in our builtin DASH parser.
            const segmentIndex = new shaka.media.MetaSegmentIndex();
            const language = video.closedCaptions.get(id);
            const textStream = {
              id: this.nextExternalStreamId_++,  // A globally unique ID.
              originalId: id, // The CC ID string, like 'CC1', 'CC3', etc.
              groupId: null,
              createSegmentIndex: () => Promise.resolve(),
              segmentIndex,
              mimeType,
              codecs: '',
              kind: TextStreamKind.CLOSED_CAPTION,
              encrypted: false,
              drmInfos: [],
              keyIds: new Set(),
              language,
              originalLanguage: language,
              label: null,
              type: ContentType.TEXT,
              primary: false,
              trickModeVideo: null,
              emsgSchemeIdUris: null,
              roles: video.roles,
              forced: false,
              channelsCount: null,
              audioSamplingRate: null,
              spatialAudio: false,
              closedCaptions: null,
              accessibilityPurpose: null,
              external: false,
              fastSwitching: false,
              fullMimeTypes: new Set([shaka.util.MimeUtils.getFullType(
                  mimeType, '')]),
            };
            manifest.textStreams.push(textStream);
            closedCaptionsSet.add(id);
          }
        }
      }
    }
  }

  /**
   * @param {shaka.extern.Variant} initialVariant
   * @param {number} time
   * @return {!Promise.<number>}
   * @private
   */
  async adjustStartTime_(initialVariant, time) {
    /** @type {?shaka.extern.Stream} */
    const activeAudio = initialVariant.audio;
    /** @type {?shaka.extern.Stream} */
    const activeVideo = initialVariant.video;

    /**
     * @param {?shaka.extern.Stream} stream
     * @param {number} time
     * @return {!Promise.<?number>}
     */
    const getAdjustedTime = async (stream, time) => {
      if (!stream) {
        return null;
      }

      await stream.createSegmentIndex();
      const iter = stream.segmentIndex.getIteratorForTime(time);
      const ref = iter ? iter.next().value : null;
      if (!ref) {
        return null;
      }

      const refTime = ref.startTime;
      goog.asserts.assert(refTime <= time,
          'Segment should start before target time!');
      return refTime;
    };

    const audioStartTime = await getAdjustedTime(activeAudio, time);
    const videoStartTime = await getAdjustedTime(activeVideo, time);

    // If we have both video and audio times, pick the larger one.  If we picked
    // the smaller one, that one will download an entire segment to buffer the
    // difference.
    if (videoStartTime != null && audioStartTime != null) {
      return Math.max(videoStartTime, audioStartTime);
    } else if (videoStartTime != null) {
      return videoStartTime;
    } else if (audioStartTime != null) {
      return audioStartTime;
    } else {
      return time;
    }
  }

  /**
   * Update the buffering state to be either "we are buffering" or "we are not
   * buffering", firing events to the app as needed.
   *
   * @private
   */
  updateBufferState_() {
    const isBuffering = this.isBuffering();
    shaka.log.v2('Player changing buffering state to', isBuffering);

    // Make sure we have all the components we need before we consider ourselves
    // as being loaded.
    // TODO: Make the check for "loaded" simpler.
    const loaded = this.stats_ && this.bufferObserver_ && this.playhead_;

    if (loaded) {
      if (this.cmcdManager_) {
        this.cmcdManager_.setBuffering(isBuffering);
      }
      this.updateStateHistory_();
    }

    // Surface the buffering event so that the app knows if/when we are
    // buffering.
    const eventName = shaka.util.FakeEvent.EventName.Buffering;
    const data = (new Map()).set('buffering', isBuffering);
    this.dispatchEvent(shaka.Player.makeEvent_(eventName, data));
  }

  /**
   * A callback for when the playback rate changes. We need to watch the
   * playback rate so that if the playback rate on the media element changes
   * (that was not caused by our play rate controller) we can notify the
   * controller so that it can stay in-sync with the change.
   *
   * @private
   */
  onRateChange_() {
    /** @type {number} */
    const newRate = this.video_.playbackRate;

    // On Edge, when someone seeks using the native controls, it will set the
    // playback rate to zero until they finish seeking, after which it will
    // return the playback rate.
    //
    // If the playback rate changes while seeking, Edge will cache the playback
    // rate and use it after seeking.
    //
    // https://github.com/shaka-project/shaka-player/issues/951
    if (newRate == 0) {
      return;
    }

    if (this.playRateController_) {
      // The playback rate has changed. This could be us or someone else.
      // If this was us, setting the rate again will be a no-op.
      this.playRateController_.set(newRate);
    }

    const event = shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.RateChange);
    this.dispatchEvent(event);
  }

  /**
   * Try updating the state history. If the player has not finished
   * initializing, this will be a no-op.
   *
   * @private
   */
  updateStateHistory_() {
    // If we have not finish initializing, this will be a no-op.
    if (!this.stats_) {
      return;
    }
    if (!this.bufferObserver_) {
      return;
    }

    const State = shaka.media.BufferingObserver.State;

    const history = this.stats_.getStateHistory();

    let updateState = 'playing';
    if (this.bufferObserver_.getState() == State.STARVING) {
      updateState = 'buffering';
    } else if (this.video_.paused) {
      updateState = 'paused';
    } else if (this.video_.ended) {
      updateState = 'ended';
    }
    const stateChanged = history.update(updateState);

    if (stateChanged) {
      const eventName = shaka.util.FakeEvent.EventName.StateChanged;
      const data = (new Map()).set('newstate', updateState);
      this.dispatchEvent(shaka.Player.makeEvent_(eventName, data));
    }
  }

  /**
   * Callback for liveSync and vodDynamicPlaybackRate
   *
   * @private
   */
  onTimeUpdate_() {
    const playbackRate = this.video_.playbackRate;
    const isLive = this.isLive();

    if (this.config_.streaming.vodDynamicPlaybackRate && !isLive) {
      const minPlaybackRate =
        this.config_.streaming.vodDynamicPlaybackRateLowBufferRate;
      const bufferFullness = this.getBufferFullness();
      const bufferThreshold =
        this.config_.streaming.vodDynamicPlaybackRateBufferRatio;

      if (bufferFullness <= bufferThreshold) {
        if (playbackRate != minPlaybackRate) {
          shaka.log.debug('Buffer fullness ratio (' + bufferFullness + ') ' +
            'is less than the vodDynamicPlaybackRateBufferRatio (' +
            bufferThreshold + '). Updating playbackRate to ' + minPlaybackRate);
          this.trickPlay(minPlaybackRate);
        }
      } else if (bufferFullness == 1) {
        if (playbackRate !== this.playRateController_.getDefaultRate()) {
          shaka.log.debug('Buffer is full. Cancel trick play.');
          this.cancelTrickPlay();
        }
      }
    }

    // If the live stream has reached its end, do not sync.
    if (!isLive) {
      return;
    }

    const seekRange = this.seekRange();
    if (!Number.isFinite(seekRange.end)) {
      return;
    }
    const currentTime = this.video_.currentTime;
    if (currentTime < seekRange.start) {
      // Bad stream?
      return;
    }

    let liveSyncMaxLatency;
    let liveSyncPlaybackRate;
    if (this.config_.streaming.liveSync) {
      liveSyncMaxLatency = this.config_.streaming.liveSyncMaxLatency;
      liveSyncPlaybackRate = this.config_.streaming.liveSyncPlaybackRate;
    } else {
      // serviceDescription must override if it is defined in the MPD and
      // liveSync configuration is not set.
      if (this.manifest_ && this.manifest_.serviceDescription) {
        liveSyncMaxLatency = this.manifest_.serviceDescription.maxLatency ||
          this.config_.streaming.liveSyncMaxLatency;
        liveSyncPlaybackRate =
          this.manifest_.serviceDescription.maxPlaybackRate ||
          this.config_.streaming.liveSyncPlaybackRate;
      }
    }

    let liveSyncMinLatency;
    let liveSyncMinPlaybackRate;
    if (this.config_.streaming.liveSync) {
      liveSyncMinLatency = this.config_.streaming.liveSyncMinLatency;
      liveSyncMinPlaybackRate = this.config_.streaming.liveSyncMinPlaybackRate;
    } else {
      // serviceDescription must override if it is defined in the MPD and
      // liveSync configuration is not set.
      if (this.manifest_ && this.manifest_.serviceDescription) {
        liveSyncMinLatency = this.manifest_.serviceDescription.minLatency ||
          this.config_.streaming.liveSyncMinLatency;
        liveSyncMinPlaybackRate =
          this.manifest_.serviceDescription.minPlaybackRate ||
          this.config_.streaming.liveSyncMinPlaybackRate;
      }
    }

    const latency = seekRange.end - this.video_.currentTime;
    let offset = 0;
    // In src= mode, the seek range isn't updated frequently enough, so we need
    // to fudge the latency number with an offset.  The playback rate is used
    // as an offset, since that is the amount we catch up 1 second of
    // accelerated playback.
    if (this.loadMode_ == shaka.Player.LoadMode.SRC_EQUALS) {
      const buffered = this.video_.buffered;
      if (buffered.length > 0) {
        const bufferedEnd = buffered.end(buffered.length - 1);
        offset = Math.max(liveSyncPlaybackRate, bufferedEnd - seekRange.end);
      }
    }

    const panicMode = this.config_.streaming.liveSyncPanicMode;
    const panicThreshold = this.config_.streaming.liveSyncPanicThreshold * 1000;
    const timeSinceLastRebuffer =
        Date.now() - this.bufferObserver_.getLastRebufferTime();
    if (panicMode && !liveSyncMinPlaybackRate) {
      liveSyncMinPlaybackRate = this.config_.streaming.liveSyncMinPlaybackRate;
    }

    if (panicMode && liveSyncMinPlaybackRate &&
        timeSinceLastRebuffer <= panicThreshold) {
      if (playbackRate != liveSyncMinPlaybackRate) {
        shaka.log.debug('Time since last rebuffer (' +
          timeSinceLastRebuffer + 's) ' +
          'is less than the liveSyncPanicThreshold (' + panicThreshold +
          's). Updating playbackRate to ' + liveSyncMinPlaybackRate);
        this.trickPlay(liveSyncMinPlaybackRate);
      }
    } else if (liveSyncMaxLatency && liveSyncPlaybackRate &&
        (latency - offset) > liveSyncMaxLatency) {
      if (playbackRate != liveSyncPlaybackRate) {
        shaka.log.debug('Latency (' + latency + 's) ' +
          'is greater than liveSyncMaxLatency (' + liveSyncMaxLatency + 's). ' +
          'Updating playbackRate to ' + liveSyncPlaybackRate);
        this.trickPlay(liveSyncPlaybackRate);
      }
    } else if (liveSyncMinLatency && liveSyncMinPlaybackRate &&
        (latency - offset) < liveSyncMinLatency) {
      if (playbackRate != liveSyncMinPlaybackRate) {
        shaka.log.debug('Latency (' + latency + 's) ' +
          'is smaller than liveSyncMinLatency (' + liveSyncMinLatency + 's). ' +
          'Updating playbackRate to ' + liveSyncMinPlaybackRate);
        this.trickPlay(liveSyncMinPlaybackRate);
      }
    } else if (playbackRate !== this.playRateController_.getDefaultRate()) {
      this.cancelTrickPlay();
    }
  }

  /**
   * Callback for video progress events
   *
   * @private
   */
  onVideoProgress_() {
    if (!this.video_) {
      return;
    }
    let hasNewCompletionPercent = false;
    const completionRatio = this.video_.currentTime / this.video_.duration;
    if (!isNaN(completionRatio)) {
      const percent = Math.round(100 * completionRatio);
      if (isNaN(this.completionPercent_)) {
        this.completionPercent_ = percent;
        hasNewCompletionPercent = true;
      } else {
        const newCompletionPercent = Math.max(this.completionPercent_, percent);
        if (this.completionPercent_ != newCompletionPercent) {
          this.completionPercent_ = newCompletionPercent;
          hasNewCompletionPercent = true;
        }
      }
    }
    if (hasNewCompletionPercent) {
      let event;
      if (this.completionPercent_ == 0) {
        event = shaka.Player.makeEvent_(shaka.util.FakeEvent.EventName.Started);
      } else if (this.completionPercent_ == 25) {
        event = shaka.Player.makeEvent_(
            shaka.util.FakeEvent.EventName.FirstQuartile);
      } else if (this.completionPercent_ == 50) {
        event = shaka.Player.makeEvent_(
            shaka.util.FakeEvent.EventName.Midpoint);
      } else if (this.completionPercent_ == 75) {
        event = shaka.Player.makeEvent_(
            shaka.util.FakeEvent.EventName.ThirdQuartile);
      } else if (this.completionPercent_ == 100) {
        event = shaka.Player.makeEvent_(
            shaka.util.FakeEvent.EventName.Complete);
      }
      if (event) {
        this.dispatchEvent(event);
      }
    }
  }

  /**
   * Callback from Playhead.
   *
   * @private
   */
  onSeek_() {
    if (this.playheadObservers_) {
      this.playheadObservers_.notifyOfSeek();
    }
    if (this.streamingEngine_) {
      this.streamingEngine_.seeked();
    }
    if (this.bufferObserver_) {
      // If we seek into an unbuffered range, we should fire a 'buffering' event
      // immediately.  If StreamingEngine can buffer fast enough, we may not
      // update our buffering tracking otherwise.
      this.pollBufferState_();
    }
  }

  /**
   * Update AbrManager with variants while taking into account restrictions,
   * preferences, and ABR.
   *
   * On error, this dispatches an error event and returns false.
   *
   * @return {boolean} True if successful.
   * @private
   */
  updateAbrManagerVariants_() {
    try {
      goog.asserts.assert(this.manifest_, 'Manifest should exist by now!');
      this.manifestFilterer_.checkRestrictedVariants(this.manifest_);
    } catch (e) {
      this.onError_(e);
      return false;
    }

    const playableVariants = shaka.util.StreamUtils.getPlayableVariants(
        this.manifest_.variants);

    // Update the abr manager with newly filtered variants.
    const adaptationSet = this.currentAdaptationSetCriteria_.create(
        playableVariants);
    this.abrManager_.setVariants(Array.from(adaptationSet.values()));
    return true;
  }

  /**
   * Chooses a variant from all possible variants while taking into account
   * restrictions, preferences, and ABR.
   *
   * On error, this dispatches an error event and returns null.
   *
   * @param {boolean=} initialSelection
   * @return {?shaka.extern.Variant}
   * @private
   */
  chooseVariant_(initialSelection = false) {
    if (this.updateAbrManagerVariants_()) {
      return this.abrManager_.chooseVariant(initialSelection);
    } else {
      return null;
    }
  }

  /**
   * Checks to re-enable variants that were temporarily disabled due to network
   * errors. If any variants are enabled this way, a new variant may be chosen
   * for playback.
   * @private
   */
  checkVariants_() {
    goog.asserts.assert(this.manifest_, 'Should have manifest!');

    const now = Date.now() / 1000;
    let hasVariantUpdate = false;

    /** @type {function(shaka.extern.Variant):string} */
    const streamsAsString = (variant) => {
      let str = '';
      if (variant.video) {
        str += 'video:' + variant.video.id;
      }
      if (variant.audio) {
        str += str ? '&' : '';
        str += 'audio:' + variant.audio.id;
      }
      return str;
    };

    for (const variant of this.manifest_.variants) {
      if (variant.disabledUntilTime > 0 && variant.disabledUntilTime <= now) {
        variant.disabledUntilTime = 0;
        hasVariantUpdate = true;

        shaka.log.v2('Re-enabled variant with ' + streamsAsString(variant));
      }
    }

    const shouldStopTimer = this.manifest_.variants.every((variant) => {
      goog.asserts.assert(
          variant.disabledUntilTime >= 0,
          '|variant.disableTimeUntilTime| must always be >= 0');
      return variant.disabledUntilTime === 0;
    });

    if (shouldStopTimer) {
      this.checkVariantsTimer_.stop();
    }

    if (hasVariantUpdate) {
      // Reconsider re-enabled variant for ABR switching.
      this.chooseVariantAndSwitch_(
          /* clearBuffer= */ true, /* safeMargin= */ undefined,
          /* force= */ false, /* fromAdaptation= */ false);
    }
  }

  /**
   * Choose a text stream from all possible text streams while taking into
   * account user preference.
   *
   * @return {?shaka.extern.Stream}
   * @private
   */
  chooseTextStream_() {
    const subset = shaka.util.StreamUtils.filterStreamsByLanguageAndRole(
        this.manifest_.textStreams,
        this.currentTextLanguage_,
        this.currentTextRole_,
        this.currentTextForced_);
    return subset[0] || null;
  }

  /**
   * Chooses a new Variant.  If the new variant differs from the old one, it
   * adds the new one to the switch history and switches to it.
   *
   * Called after a config change, a key status event, or an explicit language
   * change.
   *
   * @param {boolean=} clearBuffer Optional clear buffer or not when
   *  switch to new variant
   *  Defaults to true if not provided
   * @param {number=} safeMargin Optional amount of buffer (in seconds) to
   *   retain when clearing the buffer.
   *   Defaults to 0 if not provided. Ignored if clearBuffer is false.
   * @private
   */
  chooseVariantAndSwitch_(clearBuffer = true, safeMargin = 0, force = false,
      fromAdaptation = true) {
    goog.asserts.assert(this.config_, 'Must not be destroyed');

    // Because we're running this after a config change (manual language
    // change) or a key status event, it is always okay to clear the buffer
    // here.
    const chosenVariant = this.chooseVariant_();
    if (chosenVariant) {
      this.switchVariant_(chosenVariant, fromAdaptation,
          clearBuffer, safeMargin, force);
    }
  }

  /**
   * @param {shaka.extern.Variant} variant
   * @param {boolean} fromAdaptation
   * @param {boolean} clearBuffer
   * @param {number} safeMargin
   * @param {boolean=} force
   * @private
   */
  switchVariant_(variant, fromAdaptation, clearBuffer, safeMargin,
      force = false) {
    const currentVariant = this.streamingEngine_.getCurrentVariant();
    if (variant == currentVariant) {
      shaka.log.debug('Variant already selected.');
      // If you want to clear the buffer, we force to reselect the same variant.
      // We don't need to reset the timestampOffset since it's the same variant,
      // so 'adaptation' isn't passed here.
      if (clearBuffer) {
        this.streamingEngine_.switchVariant(variant, clearBuffer, safeMargin,
            /* force= */ true);
      }
      return;
    }

    // Add entries to the history.
    this.addVariantToSwitchHistory_(variant, fromAdaptation);
    this.streamingEngine_.switchVariant(
        variant, clearBuffer, safeMargin, force,
        /* adaptation= */ fromAdaptation);
    let oldTrack = null;
    if (currentVariant) {
      oldTrack = shaka.util.StreamUtils.variantToTrack(currentVariant);
    }
    const newTrack = shaka.util.StreamUtils.variantToTrack(variant);

    if (fromAdaptation) {
      // Dispatch an 'adaptation' event
      this.onAdaptation_(oldTrack, newTrack);
    } else {
      // Dispatch a 'variantchanged' event
      this.onVariantChanged_(oldTrack, newTrack);
    }
  }

  /**
   * @param {AudioTrack} track
   * @private
   */
  switchHtml5Track_(track) {
    goog.asserts.assert(this.video_ && this.video_.audioTracks,
        'Video and video.audioTracks should not be null!');
    const audioTracks = Array.from(this.video_.audioTracks);
    const currentTrack = audioTracks.find((t) => t.enabled);

    // This will reset the "enabled" of other tracks to false.
    track.enabled = true;

    // AirPlay does not reset the "enabled" of other tracks to false, so
    // it must be changed by hand.
    if (track.id !== currentTrack.id) {
      currentTrack.enabled = false;
    }

    const oldTrack =
      shaka.util.StreamUtils.html5AudioTrackToTrack(currentTrack);
    const newTrack =
      shaka.util.StreamUtils.html5AudioTrackToTrack(track);
    this.onVariantChanged_(oldTrack, newTrack);
  }

  /**
   * Decide during startup if text should be streamed/shown.
   * @private
   */
  setInitialTextState_(initialVariant, initialTextStream) {
    // Check if we should show text (based on difference between audio and text
    // languages).
    if (initialTextStream) {
      if (initialVariant.audio && this.shouldInitiallyShowText_(
          initialVariant.audio, initialTextStream)) {
        this.isTextVisible_ = true;
      }
      if (this.isTextVisible_) {
        // If the cached value says to show text, then update the text displayer
        // since it defaults to not shown.
        this.mediaSourceEngine_.getTextDisplayer().setTextVisibility(true);
        goog.asserts.assert(this.shouldStreamText_(),
            'Should be streaming text');
      }
      this.onTextTrackVisibility_();
    } else {
      this.isTextVisible_ = false;
    }
  }

  /**
   * Check if we should show text on screen automatically.
   *
   * @param {shaka.extern.Stream} audioStream
   * @param {shaka.extern.Stream} textStream
   * @return {boolean}
   * @private
   */
  shouldInitiallyShowText_(audioStream, textStream) {
    const AutoShowText = shaka.config.AutoShowText;

    if (this.config_.autoShowText == AutoShowText.NEVER) {
      return false;
    }
    if (this.config_.autoShowText == AutoShowText.ALWAYS) {
      return true;
    }

    const LanguageUtils = shaka.util.LanguageUtils;

    /** @type {string} */
    const preferredTextLocale =
        LanguageUtils.normalize(this.config_.preferredTextLanguage);
    /** @type {string} */
    const textLocale = LanguageUtils.normalize(textStream.language);

    if (this.config_.autoShowText == AutoShowText.IF_PREFERRED_TEXT_LANGUAGE) {
      // Only the text language match matters.
      return LanguageUtils.areLanguageCompatible(
          textLocale,
          preferredTextLocale);
    }

    if (this.config_.autoShowText == AutoShowText.IF_SUBTITLES_MAY_BE_NEEDED) {
      /* The text should automatically be shown if the text is
       * language-compatible with the user's text language preference, but not
       * compatible with the audio.  These are cases where we deduce that
       * subtitles may be needed.
       *
       * For example:
       *   preferred | chosen | chosen |
       *   text      | text   | audio  | show
       *   -----------------------------------
       *   en-CA     | en     | jp     | true
       *   en        | en-US  | fr     | true
       *   fr-CA     | en-US  | jp     | false
       *   en-CA     | en-US  | en-US  | false
       *
       */
      /** @type {string} */
      const audioLocale = LanguageUtils.normalize(audioStream.language);

      return (
        LanguageUtils.areLanguageCompatible(textLocale, preferredTextLocale) &&
        !LanguageUtils.areLanguageCompatible(audioLocale, textLocale));
    }

    shaka.log.alwaysWarn('Invalid autoShowText setting!');
    return false;
  }

  /**
   * Callback from StreamingEngine.
   *
   * @private
   */
  onManifestUpdate_() {
    if (this.parser_ && this.parser_.update) {
      this.parser_.update();
    }
  }

  /**
   * Callback from StreamingEngine.
   *
   * @private
   */
  onSegmentAppended_(start, end, contentType) {
    // When we append a segment to media source (via streaming engine) we are
    // changing what data we have buffered, so notify the playhead of the
    // change.
    if (this.playhead_) {
      this.playhead_.notifyOfBufferingChange();
      // Skip the initial buffer gap
      const startTime = this.mediaSourceEngine_.bufferStart(contentType);
      if (
        !this.isLive() &&
        // If not paused then GapJumpingController will handle this gap.
        this.video_.paused &&
        startTime != null &&
        startTime > 0 &&
        this.playhead_.getTime() < startTime
      ) {
        this.playhead_.setStartTime(startTime);
      }
    }
    this.pollBufferState_();

    // Dispatch an event for users to consume, too.
    const data = new Map()
        .set('start', start)
        .set('end', end)
        .set('contentType', contentType);
    this.dispatchEvent(shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.SegmentAppended, data));
  }

  /**
   * Callback from AbrManager.
   *
   * @param {shaka.extern.Variant} variant
   * @param {boolean=} clearBuffer
   * @param {number=} safeMargin Optional amount of buffer (in seconds) to
   *   retain when clearing the buffer.
   *   Defaults to 0 if not provided. Ignored if clearBuffer is false.
   * @private
   */
  switch_(variant, clearBuffer = false, safeMargin = 0) {
    shaka.log.debug('switch_');
    goog.asserts.assert(this.config_.abr.enabled,
        'AbrManager should not call switch while disabled!');
    goog.asserts.assert(this.manifest_, 'We need a manifest to switch ' +
                                        'variants.');

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

    if (variant == this.streamingEngine_.getCurrentVariant()) {
      // This isn't a change.
      return;
    }

    this.switchVariant_(variant, /* fromAdaptation= */ true,
        clearBuffer, safeMargin);
  }

  /**
   * Dispatches an 'adaptation' event.
   * @param {?shaka.extern.Track} from
   * @param {shaka.extern.Track} to
   * @private
   */
  onAdaptation_(from, to) {
    // Delay the 'adaptation' event so that StreamingEngine has time to absorb
    // the changes before the user tries to query it.
    const data = new Map()
        .set('oldTrack', from)
        .set('newTrack', to);
    if (this.lcevcDec_) {
      this.lcevcDec_.updateVariant(to, this.getManifestType());
    }
    const event = shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.Adaptation, data);
    this.delayDispatchEvent_(event);
  }

  /**
   * Dispatches a 'trackschanged' event.
   * @private
   */
  onTracksChanged_() {
    // Delay the 'trackschanged' event so StreamingEngine has time to absorb the
    // changes before the user tries to query it.
    const event = shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.TracksChanged);
    this.delayDispatchEvent_(event);
  }

  /**
   * Dispatches a 'variantchanged' event.
   * @param {?shaka.extern.Track} from
   * @param {shaka.extern.Track} to
   * @private
   */
  onVariantChanged_(from, to) {
    // Delay the 'variantchanged' event so StreamingEngine has time to absorb
    // the changes before the user tries to query it.
    const data = new Map()
        .set('oldTrack', from)
        .set('newTrack', to);
    if (this.lcevcDec_) {
      this.lcevcDec_.updateVariant(to, this.getManifestType());
    }

    const event = shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.VariantChanged, data);
    this.delayDispatchEvent_(event);
  }

  /**
   * Dispatches a 'textchanged' event.
   * @private
   */
  onTextChanged_() {
    // Delay the 'textchanged' event so StreamingEngine time to absorb the
    // changes before the user tries to query it.
    const event = shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.TextChanged);
    this.delayDispatchEvent_(event);
  }

  /** @private */
  onTextTrackVisibility_() {
    const event = shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.TextTrackVisibility);
    this.delayDispatchEvent_(event);
  }

  /** @private */
  onAbrStatusChanged_() {
    // Restore disabled variants if abr get disabled
    if (!this.config_.abr.enabled) {
      this.restoreDisabledVariants_();
    }

    const data = (new Map()).set('newStatus', this.config_.abr.enabled);
    this.delayDispatchEvent_(shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.AbrStatusChanged, data));
  }

  /**
   * @param {boolean} updateAbrManager
   * @private
   */
  restoreDisabledVariants_(updateAbrManager=true) {
    if (this.loadMode_ != shaka.Player.LoadMode.MEDIA_SOURCE) {
      return;
    }
    goog.asserts.assert(this.manifest_, 'Should have manifest!');

    shaka.log.v2('Restoring all disabled streams...');

    this.checkVariantsTimer_.stop();

    for (const variant of this.manifest_.variants) {
      variant.disabledUntilTime = 0;
    }

    if (updateAbrManager) {
      this.updateAbrManagerVariants_();
    }
  }

  /**
   * Temporarily disable all variants containing |stream|
   * @param {shaka.extern.Stream} stream
   * @param {number} disableTime
   * @return {boolean}
   */
  disableStream(stream, disableTime) {
    if (!this.config_.abr.enabled ||
        this.loadMode_ === shaka.Player.LoadMode.DESTROYED) {
      return false;
    }

    if (!navigator.onLine) {
      // Don't disable variants if we're completely offline, or else we end up
      // rapidly restricting all of them.
      return false;
    }

    // It only makes sense to disable a stream if we have an alternative else we
    // end up disabling all variants.
    const hasAltStream = this.manifest_.variants.some((variant) => {
      const altStream = variant[stream.type];

      if (altStream && altStream.id !== stream.id) {
        if (shaka.util.StreamUtils.isAudio(stream)) {
          return stream.language === altStream.language;
        }
        return true;
      }
      return false;
    });

    if (hasAltStream) {
      let didDisableStream = false;

      for (const variant of this.manifest_.variants) {
        const candidate = variant[stream.type];

        if (candidate && candidate.id === stream.id) {
          variant.disabledUntilTime = (Date.now() / 1000) + disableTime;
          didDisableStream = true;

          shaka.log.v2(
              'Disabled stream ' + stream.type + ':' + stream.id +
              ' for ' + disableTime + ' seconds...');
        }
      }

      goog.asserts.assert(didDisableStream, 'Must have disabled stream');

      this.checkVariantsTimer_.tickEvery(1);

      // Get the safeMargin to ensure a seamless playback
      const {video} = this.getBufferedInfo();
      const safeMargin =
          video.reduce((size, {start, end}) => size + end - start, 0);

      // Update abr manager variants and switch to recover playback
      this.chooseVariantAndSwitch_(
          /* clearBuffer= */ true, /* safeMargin= */ safeMargin,
          /* force= */ true, /* fromAdaptation= */ false);
      return true;
    }

    shaka.log.warning(
        'No alternate stream found for active ' + stream.type + ' stream. ' +
        'Will ignore request to disable stream...');

    return false;
  }

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

    // Errors dispatched after |destroy| is called are not meaningful and should
    // be safe to ignore.
    if (this.loadMode_ == shaka.Player.LoadMode.DESTROYED) {
      return;
    }

    let fireError = true;
    if (this.fullyLoaded_ && this.manifest_ && this.streamingEngine_ &&
        (error.code == shaka.util.Error.Code.VIDEO_ERROR ||
        error.code == shaka.util.Error.Code.MEDIA_SOURCE_OPERATION_FAILED ||
        error.code == shaka.util.Error.Code.MEDIA_SOURCE_OPERATION_THREW ||
        error.code == shaka.util.Error.Code.TRANSMUXING_FAILED)) {
      try {
        const ret = await this.streamingEngine_.resetMediaSource();
        fireError = !ret;
      } catch (e) {
        fireError = true;
      }
    }
    if (!fireError) {
      return;
    }

    // Restore disabled variant if the player experienced a critical error.
    if (error.severity === shaka.util.Error.Severity.CRITICAL) {
      this.restoreDisabledVariants_(/* updateAbrManager= */ false);
    }

    const eventName = shaka.util.FakeEvent.EventName.Error;
    const event = shaka.Player.makeEvent_(
        eventName, (new Map()).set('detail', error));
    this.dispatchEvent(event);
    if (event.defaultPrevented) {
      error.handled = true;
    }
  }

  /**
   * When we fire region events, we need to copy the information out of the
   * region to break the connection with the player's internal data. We do the
   * copy here because this is the transition point between the player and the
   * app.
   *
   * @param {!shaka.util.FakeEvent.EventName} eventName
   * @param {shaka.extern.TimelineRegionInfo} region
   * @param {shaka.util.FakeEventTarget=} eventTarget
   *
   * @private
   */
  onRegionEvent_(eventName, region, eventTarget = this) {
    // Always make a copy to avoid exposing our internal data to the app.
    const clone = {
      schemeIdUri: region.schemeIdUri,
      value: region.value,
      startTime: region.startTime,
      endTime: region.endTime,
      id: region.id,
      eventElement: region.eventElement,
      eventNode: region.eventNode,
    };

    const data = (new Map()).set('detail', clone);
    eventTarget.dispatchEvent(shaka.Player.makeEvent_(eventName, data));
  }

  /**
   * When notified of a media quality change we need to emit a
   * MediaQualityChange event to the app.
   *
   * @param {shaka.extern.MediaQualityInfo} mediaQuality
   * @param {number} position
   *
   * @private
   */
  onMediaQualityChange_(mediaQuality, position) {
    // Always make a copy to avoid exposing our internal data to the app.
    const clone = {
      bandwidth: mediaQuality.bandwidth,
      audioSamplingRate: mediaQuality.audioSamplingRate,
      codecs: mediaQuality.codecs,
      contentType: mediaQuality.contentType,
      frameRate: mediaQuality.frameRate,
      height: mediaQuality.height,
      mimeType: mediaQuality.mimeType,
      channelsCount: mediaQuality.channelsCount,
      pixelAspectRatio: mediaQuality.pixelAspectRatio,
      width: mediaQuality.width,
    };

    const data = new Map()
        .set('mediaQuality', clone)
        .set('position', position);

    this.dispatchEvent(shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.MediaQualityChanged, data));
  }

  /**
   * Turn the media element's error object into a Shaka Player error object.
   *
   * @return {shaka.util.Error}
   * @private
   */
  videoErrorToShakaError_() {
    goog.asserts.assert(this.video_.error,
        'Video error expected, but missing!');
    if (!this.video_.error) {
      return null;
    }

    const 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 null;
    }

    // Extra error information from MS Edge:
    let 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);
    }

    // Extra error information from Chrome:
    const message = this.video_.error.message;

    return new shaka.util.Error(
        shaka.util.Error.Severity.CRITICAL,
        shaka.util.Error.Category.MEDIA,
        shaka.util.Error.Code.VIDEO_ERROR,
        code, extended, message);
  }

  /**
   * @param {!Event} event
   * @private
   */
  onVideoError_(event) {
    const error = this.videoErrorToShakaError_();
    if (!error) {
      return;
    }
    this.onError_(error);
  }

  /**
   * @param {!Object.<string, string>} keyStatusMap A map of hex key IDs to
   *   statuses.
   * @private
   */
  onKeyStatus_(keyStatusMap) {
    goog.asserts.assert(this.streamingEngine_, 'Cannot be called in src= mode');

    const event = shaka.Player.makeEvent_(
        shaka.util.FakeEvent.EventName.KeyStatusChanged);
    this.dispatchEvent(event);

    const keyIds = Object.keys(keyStatusMap);
    if (keyIds.length == 0) {
      shaka.log.warning(
          'Got a key status event without any key statuses, so we don\'t ' +
          'know the real key statuses. If we don\'t have all the keys, ' +
          'you\'ll need to set restrictions so we don\'t select those tracks.');
    }

    // If EME is using a synthetic key ID, the only key ID is '00' (a single 0
    // byte).  In this case, it is only used to report global success/failure.
    // See note about old platforms in: https://bit.ly/2tpez5Z
    const isGlobalStatus = keyIds.length == 1 && keyIds[0] == '00';
    if (isGlobalStatus) {
      shaka.log.warning(
          'Got a synthetic key status event, so we don\'t know the real key ' +
          'statuses. If we don\'t have all the keys, you\'ll need to set ' +
          'restrictions so we don\'t select those tracks.');
    }

    const restrictedStatuses = shaka.media.ManifestFilterer.restrictedStatuses;
    let tracksChanged = false;

    goog.asserts.assert(this.drmEngine_, 'drmEngine should be non-null here.');

    // Only filter tracks for keys if we have some key statuses to look at.
    if (keyIds.length) {
      for (const variant of this.manifest_.variants) {
        const streams = shaka.util.StreamUtils.getVariantStreams(variant);

        for (const stream of streams) {
          const originalAllowed = variant.allowedByKeySystem;

          // Only update if we have key IDs for the stream.  If the keys aren't
          // all present, then the track should be restricted.
          if (stream.keyIds.size) {
            variant.allowedByKeySystem = true;

            for (const keyId of stream.keyIds) {
              const keyStatus = keyStatusMap[isGlobalStatus ? '00' : keyId];
              if (keyStatus || this.drmEngine_.hasManifestInitData()) {
                variant.allowedByKeySystem = variant.allowedByKeySystem &&
                    !!keyStatus && !restrictedStatuses.includes(keyStatus);
              }
            }
          }

          if (originalAllowed != variant.allowedByKeySystem) {
            tracksChanged = true;
          }
        }  // for (const stream of streams)
      }  // for (const variant of this.manifest_.variants)
    }  // if (keyIds.size)

    if (tracksChanged) {
      this.onTracksChanged_();
      const variantsUpdated = this.updateAbrManagerVariants_();
      if (!variantsUpdated) {
        return;
      }
    }

    const currentVariant = this.streamingEngine_.getCurrentVariant();
    if (currentVariant && !currentVariant.allowedByKeySystem) {
      shaka.log.debug('Choosing new streams after key status changed');
      this.chooseVariantAndSwitch_();
    }
  }

  /**
   * @return {boolean} true if we should stream text right now.
   * @private
   */
  shouldStreamText_() {
    return this.config_.streaming.alwaysStreamText || this.isTextTrackVisible();
  }

  /**
   * Applies playRangeStart and playRangeEnd to the given timeline. This will
   * only affect non-live content.
   *
   * @param {shaka.media.PresentationTimeline} timeline
   * @param {number} playRangeStart
   * @param {number} playRangeEnd
   *
   * @private
   */
  static applyPlayRange_(timeline, playRangeStart, playRangeEnd) {
    if (playRangeStart > 0) {
      if (timeline.isLive()) {
        shaka.log.warning(
            '|playRangeStart| has been configured for live content. ' +
            'Ignoring the setting.');
      } else {
        timeline.setUserSeekStart(playRangeStart);
      }
    }

    // If the playback has been configured to end before the end of the
    // presentation, update the duration unless it's live content.
    const fullDuration = timeline.getDuration();
    if (playRangeEnd < fullDuration) {
      if (timeline.isLive()) {
        shaka.log.warning(
            '|playRangeEnd| has been configured for live content. ' +
            'Ignoring the setting.');
      } else {
        timeline.setDuration(playRangeEnd);
      }
    }
  }

  /**
   * Fire an event, but wait a little bit so that the immediate execution can
   * complete before the event is handled.
   *
   * @param {!shaka.util.FakeEvent} event
   * @private
   */
  async delayDispatchEvent_(event) {
    // Wait until the next interpreter cycle.
    await Promise.resolve();

    // Only dispatch the event if we are still alive.
    if (this.loadMode_ != shaka.Player.LoadMode.DESTROYED) {
      this.dispatchEvent(event);
    }
  }

  /**
   * Get the normalized languages for a group of tracks.
   *
   * @param {!Array.<?shaka.extern.Track>} tracks
   * @return {!Set.<string>}
   * @private
   */
  static getLanguagesFrom_(tracks) {
    const languages = new Set();

    for (const track of tracks) {
      if (track.language) {
        languages.add(shaka.util.LanguageUtils.normalize(track.language));
      } else {
        languages.add('und');
      }
    }

    return languages;
  }

  /**
   * Get all permutations of normalized languages and role for a group of
   * tracks.
   *
   * @param {!Array.<?shaka.extern.Track>} tracks
   * @return {!Array.<shaka.extern.LanguageRole>}
   * @private
   */
  static getLanguageAndRolesFrom_(tracks) {
    /** @type {!Map.<string, !Set>} */
    const languageToRoles = new Map();
    /** @type {!Map.<string, !Map.<string, string>>} */
    const languageRoleToLabel = new Map();

    for (const track of tracks) {
      let language = 'und';
      let roles = [];

      if (track.language) {
        language = shaka.util.LanguageUtils.normalize(track.language);
      }

      if (track.type == 'variant') {
        roles = track.audioRoles;
      } else {
        roles = track.roles;
      }

      if (!roles || !roles.length) {
        // We must have an empty role so that we will still get a language-role
        // entry from our Map.
        roles = [''];
      }

      if (!languageToRoles.has(language)) {
        languageToRoles.set(language, new Set());
      }

      for (const role of roles) {
        languageToRoles.get(language).add(role);
        if (track.label) {
          if (!languageRoleToLabel.has(language)) {
            languageRoleToLabel.set(language, new Map());
          }
          languageRoleToLabel.get(language).set(role, track.label);
        }
      }
    }

    // Flatten our map to an array of language-role pairs.
    const pairings = [];
    languageToRoles.forEach((roles, language) => {
      for (const role of roles) {
        let label = null;
        if (languageRoleToLabel.has(language) &&
            languageRoleToLabel.get(language).has(role)) {
          label = languageRoleToLabel.get(language).get(role);
        }
        pairings.push({language, role, label});
      }
    });
    return pairings;
  }

  /**
   * Assuming the player is playing content with media source, check if the
   * player has buffered enough content to make it to the end of the
   * presentation.
   *
   * @return {boolean}
   * @private
   */
  isBufferedToEndMS_() {
    goog.asserts.assert(
        this.video_,
        'We need a video element to get buffering information');
    goog.asserts.assert(
        this.mediaSourceEngine_,
        'We need a media source engine to get buffering information');
    goog.asserts.assert(
        this.manifest_,
        'We need a manifest to get buffering information');

    // This is a strong guarantee that we are buffered to the end, because it
    // means the playhead is already at that end.
    if (this.video_.ended) {
      return true;
    }

    // This means that MediaSource has buffered the final segment in all
    // SourceBuffers and is no longer accepting additional segments.
    if (this.mediaSourceEngine_.ended()) {
      return true;
    }

    // Live streams are "buffered to the end" when they have buffered to the
    // live edge or beyond (into the region covered by the presentation delay).
    if (this.manifest_.presentationTimeline.isLive()) {
      const liveEdge =
          this.manifest_.presentationTimeline.getSegmentAvailabilityEnd();
      const bufferEnd =
          shaka.media.TimeRangesUtils.bufferEnd(this.video_.buffered);

      if (bufferEnd != null && bufferEnd >= liveEdge) {
        return true;
      }
    }

    return false;
  }

  /**
   * Assuming the player is playing content with src=, check if the player has
   * buffered enough content to make it to the end of the presentation.
   *
   * @return {boolean}
   * @private
   */
  isBufferedToEndSrc_() {
    goog.asserts.assert(
        this.video_,
        'We need a video element to get buffering information');

    // This is a strong guarantee that we are buffered to the end, because it
    // means the playhead is already at that end.
    if (this.video_.ended) {
      return true;
    }

    // If we have buffered to the duration of the content, it means we will have
    // enough content to buffer to the end of the presentation.
    const bufferEnd =
        shaka.media.TimeRangesUtils.bufferEnd(this.video_.buffered);

    // Because Safari's native HLS reports slightly inaccurate values for
    // bufferEnd here, we use a fudge factor.  Without this, we can end up in a
    // buffering state at the end of the stream.  See issue #2117.
    const fudge = 1;  // 1000 ms
    return bufferEnd != null && bufferEnd >= this.video_.duration - fudge;
  }

  /**
   * Create an error for when we purposely interrupt a load operation.
   *
   * @return {!shaka.util.Error}
   * @private
   */
  createAbortLoadError_() {
    return new shaka.util.Error(
        shaka.util.Error.Severity.CRITICAL,
        shaka.util.Error.Category.PLAYER,
        shaka.util.Error.Code.LOAD_INTERRUPTED);
  }
};

/**
 * In order to know what method of loading the player used for some content, we
 * have this enum. It lets us know if content has not been loaded, loaded with
 * media source, or loaded with src equals.
 *
 * This enum has a low resolution, because it is only meant to express the
 * outer limits of the various states that the player is in. For example, when
 * someone calls a public method on player, it should not matter if they have
 * initialized drm engine, it should only matter if they finished loading
 * content.
 *
 * @enum {number}
 * @export
 */
shaka.Player.LoadMode = {
  'DESTROYED': 0,
  'NOT_LOADED': 1,
  'MEDIA_SOURCE': 2,
  'SRC_EQUALS': 3,
};

/**
 * The typical buffering threshold.  When we have less than this buffered (in
 * seconds), we enter a buffering state.  This specific value is based on manual
 * testing and evaluation across a variety of platforms.
 *
 * To make the buffering logic work in all cases, this "typical" threshold will
 * be overridden if the rebufferingGoal configuration is too low.
 *
 * @const {number}
 * @private
 */
shaka.Player.TYPICAL_BUFFERING_THRESHOLD_ = 0.5;

/**
 * @define {string} A version number taken from git at compile time.
 * @export
 */
// eslint-disable-next-line no-useless-concat
shaka.Player.version = 'v4.7.0' + '-uncompiled';  // x-release-please-version

// Initialize the deprecation system using the version string we just set
// on the player.
shaka.Deprecate.init(shaka.Player.version);


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


/** @private {?shaka.extern.IAdManager.Factory} */
shaka.Player.adManagerFactory_ = null;


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