code: function init(entry) {  // {{{2
  /**
   * Socket constructor
   *
   * @param entry {Object} Media player entry
   *
   * @method constructor
   */
  
    if ('playbackSocket' in entry) {
      throw O.log.error(this, 'DUPLICIT_PLAYBACK', entry.toString());
    }
  
    entry.playbackSocket = this;
    this.entry = entry;
  
    entry.shard.track(entry.dval.playback, this);
  }
docs: @caption Media player-to-playback client socket
  
  @readme
  Establish a [link] to a playback entry.
  
  @class media.lib.player.playback
  @type class
   Public {{{1