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A Scalable Video-On-Demand System Using Multi-Batch Buffering Techniques

A Scalable Video-On-Demand System Using Multi-Batch Buffering Techniques. Cyrus C. Y. Choi and Mounir Hamdi, Member, IEEE. IEEE ‘03 Transactions on Broadcasting. Outline. Introduction The Multi-Batch Buffer (MBB) system Normal playback request VCR-like interaction request

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A Scalable Video-On-Demand System Using Multi-Batch Buffering Techniques

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  1. A Scalable Video-On-Demand System Using Multi-Batch Buffering Techniques Cyrus C. Y. Choi and Mounir Hamdi, Member, IEEE IEEE ‘03 Transactions on Broadcasting

  2. Outline • Introduction • The Multi-Batch Buffer (MBB) system • Normal playback request • VCR-like interaction request • Simulation results

  3. Introduction • The current research focus on VoD system is on how to lower their cost and make them more scalable. • Services providing is essential to both normal playback and VCR-like interaction requests.

  4. Previous works • Batching • Same video stream serves multiple users through multicast • Resource sharing (video stream, bandwidth) • Poor VCR-like interactions • Split and merge (SAM) • Based on batching • Uses the synch buffer to handle interaction requests • Demands a high I/O power in the access node

  5. Multi-Bach Buffer (MBB) • Server • Store video frames in the disk • Local server • Be used to create virtual video streams (VVS) • Set top box (STB) • Located at the customers’ side, can be either a hard disk or RAM • Real video streams (RVS) • The video streams create by fetching video frames stored in the disks of the video server • Virtual video streams (VVS) • The video streams construct by prefetching RVSs or VVSs at the local servers’ buffer • STB-VVS • The virtual video stream created from set top box (STB) buffer

  6. Multi-Batch Buffer (MBB) Broadcast RVSs Create VVSs Buffer of set top box

  7. Multi-Batch Buffer (MBB) • Based on a hierarchy of storage devices • Ensure multiples of batch time (Tb) between the start time of any two video streams

  8. Introduction • The Multi-Batch Buffer (MBB) system • Normal playback request • VCR-like interaction request • Simulation results

  9. Handling of video requests • Reserve state • A video stream is waiting for the requests • Operation state • A video stream is serving the customers • Potential video stream (PVS) • A video stream possible to be the source video stream

  10. Video start requests (VSR) add to the batch group Case i) A PVS exists in the reserve state Case ii) A PVS exists in the operation state Case iii) No PVS exists  request a new RVS

  11. Video interaction requests (VIR) STB buffering SVS Tdiff Interaction stream Interaction request Case i) Tdiff <= Tstbbuffer

  12. Video interaction requests (VIR) Local S SVS-L STB buffer time STB buffering VVS Tvvsdiff Interaction stream Interaction request Case ii) Tstbbuffer < Tdiff <= Tb

  13. Compared with SAM • Video streams always start at i * Tb (i: integer) • Easier to find a virtual video stream • Supplies the buffer closer to the customers • Reduces bandwidth consumption of the local server

  14. Variation of MBB • MI • 1) Improves video start requests (VSR) with VVRs • 2) Extends buffer size of STB and local server to Tb (two times the size of origin)

  15. Simulation (1) • Video population distribution • Zipf distribution: S * log (i) • Video interaction modeling • Probability of p for interaction requests • Number of RVSs and IVSs • 50~300 and 25~200 resp. • VSR arrival rate • 60, 80, 120, 180, 360, 1200 req./hr • Video length • 2 hr. • Basic resources • Include RVS, VVS, STB-VVS, …

  16. Result (1) S=1: 100/20 (100% of customers select the top 20% of the videos) S=4: 80/20 S=10: 50/20 High  low video probabilities distribution SAM vs. MBB: arrival rate & resources requirement

  17. Result (1) SAM vs. MBB: Effective Batch time SAM vs. MBB: Average number of VSRs handled by a RVS

  18. Result (2) Interaction handling of SAM and MBB system

  19. Result (2) The reasons why the VIRs are not handled by VVS in the SAM and MBB system

  20. Result (3) Percentage of VSRs handled by VVSs in MI system with zero blocking probabilities MBB vs. MI: arrival rate & resources requirement

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