A system control unit sets stream_id of each reproduced elementary stream and the total number of streams in each of the elementary stream from management information read from a medium. Wavelet transform coefficients of each tile obtained by segmentation are output. In response to receiving a data message, the remote direct memory access protocol places a data portion of the data message into the receive buffer and prevents further changes. A drive shaft is connectable to one of the second shafts by a first gear set having a high speed ratio, and is connectable to one of the first shafts by a second gear set having a low speed ratio.