视频服务器中视频流存储分配算法的研究

STUDY OF ALGORITHMS ABOUT STORAGE ALLOCATION OF VIDEO STREAM IN VIDEO SERVER

飞速发展的网络和存储技术使为大量的用户同时提供视频点播功能的VOD系统成为可能，目前已有一批这样的系统问世，但这些系统为了保证一定数目的并发点播流，都预留了大量的设备资源，这需以较高的系统成本为代价；为了充分利用系统资源，使VOD真正走向实用，迫切需要对VOD系统的支撑技术进行深入地研究．本文以充分利用磁盘的存储空间和带宽为目的，针对视频流的存储进行了量化分析，在保证视频流正常播放的情况下，提出了在磁盘上存储多路视频流的一种合并技术；我们描述了一种把磁盘参数特性与视频流的播放特性关联起来的模型，在保证实时回取的前提下，导出了MPEG视频流的存储模式，提出了如何在磁盘上存储多路视频流的方法，以及一个磁盘最多能存放多少路需同时播放的视频流的算法，这包括一种脱机合并算法和一种在线合并算法．

Rapid advances in network and storage technologies have made it possible to build a Video-On-Demand system that can order video for a large of sub-scribers simultaneously. Up to now there are some such VOD system having comeinto the market. But these systems all reserve a larger of system's device resourcein order to assure a certain number of video stream to been played back simultane-ously, which is at the cost of very expensive system's costing. The stringent de-mands are placed on the depth study of the VOD support technology to make fulluse of the system resource and make the VOD truly come into application. In thispaper, in order to make full use of disk storage space and transfer bandwidth weproceed a quantitative study of video streams storage and under the constraint ofguaranteeing video playback rates present a merging technique for storing multiplevideos on disk. A model that relates disk characteristics to the video stream playbackrate is described, a storage pattern that guarantees real-time retrieval of MPEGvideo streams is derived. Furthermore, the methods of how to storage multiplevideo steam on a disk and algorithms for storage of maximum number of videostream that need to be played back simultaneously on a disk are presented, in whichboth off-line merging algorithm and on-line merging algorithm are included.