Get current valid caption tracks If update is false it will also ignore tracks without metadata This is used to "freeze" the language options when captions.update is false
function getTracks() {
	    var _this2 = this;

	    var update = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : false;
	    // Handle media or textTracks missing or null
	    var tracks = Array.from((this.media || {}).textTracks || []); // For HTML5, use cache instead of current tracks when it exists (if captions.update is false)
	    // Filter out removed tracks and tracks that aren't captions/subtitles (for example metadata)

	    return tracks.filter(function (track) {
	      return !_this2.isHTML5 || update || _this2.captions.meta.has(track);
	    }).filter(function (track) {
	      return ['captions', 'subtitles'].includes(track.kind);
	    });
	  }