Look-ahead scheduling to support pause-resume for video-on-demand applications

Abstract

In a video-on-demand (VOD) system, it is desirable to support pause-resume function. The requirement that each viewer be able to independently pause the video at any instant and later resume the viewing with little delay can cause difficulties in batching viewers for each showing. The conventional approach to support on-demand pause-resume provides one video access stream to disks for each video request. In this paper, we propose a more efficient mechanism to support the pause-resume feature using look-ahead scheduling with look-aside buffering. The idea is to use buffering to improve the number of concurrent viewers supportable. The concept of look-ahead scheduling is not to back up each viewer with a real stream capacity so he can pause and resume at any time, but rather to back it up with a (look-ahead) stream that is currently being used for another showing that is close to completion. Before the look-ahead stream becomes available, the pause and resume features have to be supported by the original stream through (look-aside) buffering of the missed content. It is shown via simulations that the proposed scheme can provide a substantial improvement in throughput as compared to the approach with no batching. Furthermore, for a given amount of buffer, the improvement in throughput grows more than linearly with the stream capacity of the server.