Buffer/Latency Tradeoff in Video Servers

Abstract

The study presents a queuing model for a variable workload of a video server. We show that to keep queuing delay small, the server must have some extra capacity, i.e. support more video streams. Most other studies consider the case when the load is constant and equal to the maximum number of streams supported by the server. In such a case, it is reasonable to start new movies as soon as possible because there is no external queuing delay. However, when several videos are started too close to each other in the service round, fragments for all these videos but one have to be prefetched. This introduces a high memory requirement. We discuss a possible approach to decrease the memory requirement. If video starts are distributed evenly within the service round, no prefetching is needed and the maximum required buffer is much smaller. The additional start delay introduced by this approach should be relatively small when compared with queuing delay due to the required extra capacity of the se..