具成本效益且提供VCR操作的視訊伺服器

Abstract

在隨意視訊服務中，視訊伺服器扮演一個很重要的角色。一個好的視訊伺 服器除了要快速的處理客戶端的播放要求，還要能夠符合經濟效益。這篇 論文提供了一個有成本效率的方法，除了使視訊伺服器可以快速處理客戶 端的要求，還可以提供如快轉、倒轉等ＶＣＲ操作命令。這篇論文主要介 紹一個視訊資料擺放的方法，這個方法考慮MPEG壓縮方式而將視訊資料分 割，使視訊伺服器可以提供快轉等功能。除了將ＭＰＥＧ壓縮方法加入考 量外，還提出一個即時排程法，這方法可以使用戶端不會有中斷現象，而 且提供了更好的服務品質。根據這個方法還提出了一個可以讓視訊伺服器 可以確實掌握系統資源以防止視訊資料流之間彼此影響的進入控制方法。 將所提出的方法整合後，可以得到一個可以提供ＶＣＲ操作的視訊伺服器 。這篇論文中也介紹一個經濟價值分析的模型，透過模型的分析，可以得 到視訊伺服器最佳的參數。我們也做了模擬的視訊伺服器，來測量所提方 法的效能，並和其他方法作比較，來證明所提出的方法較具有成本效率。 In video-on-demand (VOD) services, the video server plays an important role. The design of a good video server should not only consider managing the users' requests quickly, but also take the cost into consideration. This thesis describes a cost- effective solution to the video-on-demand server that not only manages users' requests quickly, but also supports VCR operations such as play, fast-forward, and rewind. Basically, we present a video placement scheme that partitions videos according to MPEG encoding techniques to provide efficient support for fast-forward operations in video servers. In addition to the placement scheme taking MPEG encoding into consideration, we also present a simple real-time scheduling scheme that makes the playback of clients starvation-free and provides better quality of service (QOS). With this scheduling scheme, we also present an admission control policy that can thoroughly handle all system resources to prevent the interference among streams. By the integration of these schemes, we can obtain a video server that can support VCR operations efficiently. A cost model of the proposed video-on-demand server was also established in this thesis. By analysis of this cost model, we will get the cost function of the server and the parameters that make video server cost-effective. We do some simulations to demonstrate the performance of proposed schemes and do some comparisons between the performance of our proposed schemes and that of other schemes to show that our proposed schemes are cost-effective.