Delay Sensitive Multimedia on Disks

Delay sensitive multimedia data, e.g. audio and video, has real time requirements for presentation to the user. These requirements dictate new methods for systems which handle delay sensitive data. In this paper we give a tutorial on supporting delay sensitive data. We show that an optimal disk scheduling algorithm exists for delay sensitive retrieval: the pre-seeking sweep algorithm. In addition, we demonstrate that it is possible to perform sub-cluster cuts and pastes in constant time – an important property for delay sensitive files which tend to be very large. A description is given of the design of the Audition system, which applies the concepts in this paper to support high-quality multi-channel digital audio on a personal computer platform. We find that off-the-shelf SCSI hard drives are capable of supporting such high performance systems.