The great progresses in computer and network technologies make applications of distributed multimedia ever more popular. Various commercial products have been presented in these years such as electronic commerce, video-on-demand, teleconferencing, tele-medicine, distance education and digital library. The basic architecture of a distributed multimedia system contains three parts—the server subsystem, the network subsystem and the client subsystem, as shown in Figure 1 (Chang, et al., 1997; Chang, 1996; Gemmell and Han, 1994; Rangan and Vin, 1993). Server subsystem: Media data are stored in the storage devices of server subsystem, such as hard disks and CD-ROM, by data placement schemes (Wang, et al., 1997; Lougher and Shepherd, 1993; Vin and Rangan, 1991). When user requests are presented, media data must be retrieved from storage devices to system buffer under pre-specified timing requirements (Tindell and Burns, 1994).
