An Efficient Video-on-Demand Model

• Authors: William E. Wright
• Venue: Computer
• Year: 2001

The author proposes a design for an efficient video-on-demand system that uses a practical, technologically sophisticated model to serve the home movie-viewing needs of a wide audience, including meeting peak demand for popular, newly released films. In this VoD model, each customer's VoD terminal connects to a television set and the network. Using the network, the customer contacts the VoD provider to request a movie at a specific time. The movie plays without interruption unless the user decides to pause it. The VoD network's bandwidth permits data transfer at a rate equal to or exceeding the rate at which the TV consumes the data. The terminal buffer's large capacity permits uninterrupted movie playing. The system includes the scheduling algorithm, buffer policy, file-storage lay-out, and a feedback mechanism for denying new requests when the system becomes nearly saturated. OEID--one-way elevator with interleaving and delayed start--includes a one-way elevator algorithm for each disk for each round and provides double buffering for each video stream. Other features include interleaved movie file storage and transmission of a warning message when the terminal nears starvation. Interleaving with delayed start offers the optimal strategy for storing movie files on disks because it permits maximum overlap of the read operations--seek, latency, and transfer-- over all disks, whereas striping overlaps only the transfer component. Also, OEID permits an almost perfectly balanced workload over all disks, on every round, regardless of movie popularity.