Disk-based storage for scalable video

We consider the placement of scalable video data on single and multiple disks for storage and real-time retrieval. For the single-disk case, we extend the principle of constant frame grouping from constant bit rate (CBR) to variable bit rate (VBR) scalable video data. When the number of admitted users exceeds the server capacity, the rate of data sent to each user is reduced to relieve the disk system overload, offering a graceful degradation in comparison with nonscalable data. We examine the qualities of video reconstructions obtained from a real disk video server and find the scalable video more visually appealing. In the VBR case, scalability is also used to improve interactivity by reducing the delay associated with using interactive functions in a predictive admission control environment. Finally, we consider the multiple disk scenario and prove that periodic interleaving results in lower system delay than striping in a video server using round-robin scheduling. We verify the results through detailed simulation of a four-disk array.