getQualityMark_(width, height) {
    if (!width || !height) {
      return '';
    }
    let trackHeight = height;
    let trackWidth = width;
    if (trackHeight > trackWidth) {
      // Vertical video.
      [trackWidth, trackHeight] = [trackHeight, trackWidth];
    }
    const aspectRatio = trackWidth / trackHeight;
    if (aspectRatio > (16 / 9)) {
      trackHeight = Math.round(trackWidth * 9 / 16);
    }
    const qualityMarks = this.controls.getConfig().qualityMarks;
    if (trackHeight >= 8640) {
      return trackHeight + 'p';
    } else if (trackHeight >= 4320) {
      return qualityMarks['4320'];
    } else if (trackHeight >= 2160) {
      return qualityMarks['2160'];
    } else if (trackHeight >= 1440) {
      return qualityMarks['1440'];
    } else if (trackHeight >= 1080) {
      return qualityMarks['1080'];
    } else if (trackHeight >= 720) {
      return qualityMarks['720'];
    }
    return '';
  }
@param {?number} width
@param {?number} height
@return {string}
@private