即時視訊系統之雛型設計與效能分析

Abstract

由於近年來在通訊及電腦技術方面的急速進步﹐將這兩方面的技術應用 於多媒體系統中已是一股潮流。 結合這些技術能夠提供人們高度便利的 資訊環境。多媒體通訊服務在很多的應用範圍中﹐舉凡教育到娛樂各方面 都愈來愈普及與重要。視訊會議與即時視訊系統是這當中最重要的應用。 其中即時視訊系統目前被視為有線電視所提供服務中最具吸引力的一項而 且含有大量潛在商機。在本篇論文中﹐我們研究了相關之郭□弇s作了一 個高效能的即時視訊系統雛型。尤其是我們提出了一個即時視訊系統中有 關 緩衝區管理的改進方法。至於即時視訊系統中的視訊伺服器方面﹐我 們主要著重於磁碟排程､緩衝區排程､以及允諾控制之演算法的研究﹐此 外我們也探討了流程控制方法。最後﹐我們實作了一個架構於QNX即時作 業系統上的即時視訊系統雛型-SVQ系統﹐並將我們所提出的方法應用其上 以及分析這套SVQ系統的效能。 Due to the rapid advance in communication and computer technologies in recents. A service that combines these technologies can provide people an information environment with significant convenience and wonderful experience. In many application domain from education to entertainment, multimedia communication service has become more and more popular and imp□ □nt. Teleconferencing and VOD ( Video-on-demand) are two of the most important applications using this concept. VOD is considered as the most attractive service that a CATV company will provide and it contains great potential business benefits. In this thesis we detail the issues of designing and implementing a high-performance VOD system with real-time data transfer capability. Especially, we present a method toimprove the buffer management scheme of VOD system. Regarding the VOD server,we focus on disk scheduling , buffer scheduling and admission control algorithms. We also address the problem of flow control in detail. We implement a prototype of VOD system based on the method we have proposed , called SVQ (SimpleVideo- on-demand system based on QNX) system, and we analyze the performance of SVQ system.