Hierarchical video patching with optimal server bandwidth
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)
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In recent years, a number of sophisticatedarchitectures have been proposed to provide VoD serviceusing multicast transmissions. Compared to their unicastcounterparts, these multicast VoD systems are highlyscalable and can potentially serve millions of concurrentusers. Nevertheless, these systems are designed forstreaming constant-bit-rate (CBR) encoded videos andthus cannot benefit from the improved visual qualityobtainable from variable-bit-rate (VBR) encodingtechniques. To tackle this challenge, this paper presents anovel Slice-and-Patch (S&P) algorithm to support VBRvideo streaming in a multicast VoD system. Extensivetrace-driven simulations are conducted to compareperformance of the S&P algorithm with two otheralgorithms based on priority scheduling. Results showthat the S&P algorithm outperforms the other two priorityscheduling algorithms for most videos. Compared to theCBR counterpart serving videos of the same averagebitrate, the S&P algorithm is able to support VBR videostreaming with only 50% increase in latency. Given thatVBR-encoded video can achieve visual qualitycomparable to CBR-encoded video at half the bitrate, thisS&P algorithm can potentially achieve performcomparable to CBR-based systems when combined withVBR encoding techniques.