Off-line and on-line guaranteed start-up delay for media-on-demand with stream merging

We address the problem of designing efficient solutions for media-on-demand in systems that use stream merging. In a stream merging system, the receiving bandwidth of clients is larger than the playback bandwidth and clients can buffer parts of the transmission to be played back later. Intelligent use of these resources allows bandwidth usage to be reduced exponentially over traditional unicast delivery of popular media. We design an off-line algorithm that, in O(n) time, computes an optimal off-line stream merging solution for the case when the time horizon n is known ahead of time. In addition, we describe an on-line delay guaranteed solution that operates without knowledge of the time horizon size, and show that it performs asymptotically close to the optimal off-line algorithm. The on-line algorithm is simpler to implement than previously proposed on-line stream merging algorithms, and empirically performs well when the intensity of client arrivals is high.