Method setDateTimeMappingForStart

src/sync-controller.js:495–510

* Save the mapping from playlist's ProgramDateTime to display. This should only happen * before segments start to load. * * @param {Playlist} playlist - The currently active playlist

(playlist)

   * @param {Playlist} playlist - The currently active playlist
   */
  setDateTimeMappingForStart(playlist) {
    // It's possible for the playlist to be updated before playback starts, meaning time
    // zero is not yet set. If, during these playlist refreshes, a discontinuity is
    // crossed, then the old time zero mapping (for the prior timeline) would be retained
    // unless the mappings are cleared.
    this.timelineToDatetimeMappings = {};

    if (playlist.segments &&
        playlist.segments.length &&
        playlist.segments[0].dateTimeObject) {
      const firstSegment = playlist.segments[0];
      const playlistTimestamp = firstSegment.dateTimeObject.getTime() / 1000;

      this.timelineToDatetimeMappings[firstSegment.timeline] = -playlistTimestamp;
    }
  }

  /**
   * Calculates and saves timeline mappings, playlist sync info, and segment timing values