Video on Demand with VBR Encoded Video

本研究探讨新兴宽频网路如何有效地传送视讯点播。本研究假设视频是可变比特率（VBR）编码。将特别强调pi最近设计的一种设计，即加入最短队列（JSQ）预取。这个令人兴奋的设计不仅提供了恒定质量的播放和几乎100%的链接利用率，而且还允许在用户请求时立即开始视频，并对交互操作（暂停/恢复和时间跳转）进行近乎瞬时的响应。本研究将研究视频点播的两种不同的端到端架构。在第一种架构中，有一个视频服务器，所有视频都来自该服务器；视频服务器连接到电缆前端或ADSL交换机。在第二种架构中，有多个视频服务器，并且有一个复杂的多链路网络，将服务器与客户端分开。本研究将研究第一种体系结构的JSQ预取；它将研究一种基于优先级的方案，该方案模仿了第二个体系结构的JSQ预取。本研究还将为我们的JSQ预取设计开发基于分析的呼叫接纳规则。研究如何利用MPEG-1和MPEG-2编码的特殊结构在服务器端设计呼叫接纳方案和选择性弃包方案。它将开发一种辅助有效载荷规范，用于通过实时协议（RTP）按需传输MPEG 1和MPEG 2视频。最后，将开发一个JSQ预取方案的实现，该方案将同时向客户端传输多个视频。该研究详情见http://www.seas.upenn.edu/~ross/jsq.html。

This research studies how emerging broadband networks can efficiently deliver video on demand. The research assumes that video is variable-bit-rate (VBR) encoded. Particular emphasis will be placed on a design which the P.I.s have recently devised, Join-the-Shortest-Queue (JSQ) Prefetching. Not only does this exciting design give constant-quality playback and almost 100% link utilization, but it also allows for immediate commencement of the video upon user request and near instantaneous response to interactive actions (pause/resume and temporal jumps). This research will examine two distinct end-to-end architectures for video on demand. In the first architecture, there is one video server from which all the videos emanate; the video server is attached to a cable headend or to an ADSL switch. In the second architecture, there are multiple video servers and there is a complex, multi-link network which separates the servers from the clients. The research will study JSQ prefetching for the first architecture; it will study a priority-based scheme which mimics JSQ prefetching for the second architecture. This research shall also develop analytically based call-admission rules for our JSQ prefetching design. It shall investigate how the special structure of MPEG-1 and MPEG-2 encoding can be exploited for designing call admission schemes and selective packet discard schemes at the server. It shall develop an auxiliary payload specification for transporting MPEG 1 and 2 video on demand over real-time protocol (RTP). Finally, an implementation of the JSQ prefetching scheme, which will stream several simultaneous videos to clients, will be developed. The research is described at http://www.seas.upenn.edu/~ross/jsq.html .