Shahram Ghandeharizadeh
Email: shahram@cs.usc.edu

Topic: Design and Implementation of Continuous Media Server

• Assigned: Stream-based Versus Structured Video Objects: Issues, Solutions, and Challenges (pdf, In Multimedia Database Systems: Issues and Research Directions, Springer Verlag, 1996,
• Optional paper #1: Striping in Multi-disk Video Servers (pdf, In Proceedings of the SPIE High-Density Data Recording and Retrieval Technologies Confernece, Oct. 1995)
• Optional paper #2: On the Complexity of Coordinated Display of Multimedia Objects (pdf, In Theoretical Computer Scinece, Volume 242, Issue 1-2, July 2000, pdf)

Questions:

• Assume a database consisting of a single media type; MPEG-2 video clips with 4 megabit per second bandwidth requirement. Visit the seagate web site and locate one of their 73 gigabyte, Ultra 160 disk drive. Lookup its external transfer rate, average seek and rotational latency times to compute the following as a function of disk block size: worst case latency, number of simultaneous displays supported by the disk drive, percentage of the wasted disk bandwidth. Consider the following block sizes: 128K, 512K, 1024K and 2048K. Please detail what values you chose for external disk transfer rate, average seek and rotational latency times.
• With a hierarchical storage organization, one approach may materialize all slices that constitute an object on the magnetic disk storage. An alternative approach may materialize only the first slice of all video clips on the available magnetic disk storage. Describe the tradeoff between these two approaches.
• An alternative to REBECA is to utilize the disk scheduling algorithm. The idea is to initiate the display of blocks that constitute a time period at the end of the time period. With this strategy, the retrieval of blocks during a time period can utilize the SCAN disk scheduling algorithm. Compare and contrast this approach with REBECA. Can REBECA be combined with the approach?