Real time stream server for handling a plurality of real time stream data with different data rates

A real time stream server capable of realizing a supply of a plurality of real time stream data with different data rates by a scheduling scheme using constant time-slot interval and transfer start timing period. A number of unit streams to be used and a block transfer time for each real time stream data are determined according to a data rate of each real time stream data. Each real time stream data is divided into a plurality of blocks, each block being in a size to be transferred within the block transfer time, and the blocks are sequentially distributed among the unit streams to be used. The blocks of each unit stream data are sequentially stored into a plurality of disk devices. In response to a request for each real time stream data from a client, the blocks constituting each real time stream data are read out from disk devices to a buffer memory, and each real time stream data is read out from a buffer memory and transferred to the client through a network, according to an appropriately scheduled transfer start timing for each unit stream.