--------------------+
            |    |mfhd|    |    |    |    |    |    | Movie Fragment Header Box    |
            +----+----+----+----+----+----+----+----+------------------------------+
            |    |traf|    |    |    |    |    |    | Track Fragment Box           |
            +----+----+----+----+----+----+----+----+------------------------------+
            |    |    |tfhd|    |    |    |    |    | Track Fragment Header Box    |
            +----+----+----+----+----+----+----+----+------------