pasp_(streamInfo) {
    if (!streamInfo.hSpacing && !streamInfo.vSpacing) {
      return new Uint8Array([]);
    }
    const Mp4Generator = shaka.util.Mp4Generator;
    const hSpacing = streamInfo.hSpacing;
    const vSpacing = streamInfo.vSpacing;
    const bytes = new Uint8Array([
      ...this.breakNumberIntoBytes_(hSpacing, 4), // hSpacing
      ...this.breakNumberIntoBytes_(vSpacing, 4), // vSpacing
    ]);
    return Mp4Generator.box('pasp', bytes);
  }
Generate a PASP box

@param {shaka.util.Mp4Generator.StreamInfo} streamInfo
@return {!Uint8Array}
@private