連續式媒體在FDDI-II網路上之模擬與分析

Abstract

在分散式多媒體計算系統中，多媒體應用程式的設計是為了處理各種型態 的資訊，這些資訊包括文字、圖形、影像、聲音和視訊。在所有的媒體中 ，聲音和視訊會隨著時間而連續更替所顯示的資料，因此它們被稱做連續 式媒體。在這篇論文裡，我們分析連續式媒體在分散式多媒體計算系統中 的通訊情形。這個系統被分成 3 個子系統以利分析。首先，我們介紹伺 服子系統。我們計算一個儲存伺服機所能允許之最大數量的匯流申請以及 它所須要的緩衝區大小。然後，我們提出一個監控申請同意權的策略以供 儲存伺服機使用。其次，我們討論網路子系統。我們建立一個 M/G/1 渡 假模型來分析 FDDI-II 網路。藉此，我們檢視線路轉接服務的比例，作 用許可目標巡迴時間的長短，和同步框包服務時間的比例，對於網路候伺 延遲的影響。然後，我們建議一些有關 FDDI-II 網路參數設定的策略。 最後，我們分析顯視子系統。我們先探討相關於固定速率編碼之視訊位元 匯流的視訊緩衝驗證器( VBV )。然後提出一個方法來計算 VBV 緩衝區的 大小和起始VBV 的延遲。我們並提出一些有關視訊匯流之圖片配置的原則 。 In distributed multimedia computing system, multimedia applications are designed to handle various types of information such as text, graphics, image, audio, and video. Of all the media sources, audio and video are perceived as changing continuously over time and are called continuous media. In this thesis, the communication behaviors of continuous media in a distributed multimedia computing system are analyzed. The system is decomposed into 3 subsystems for analysis. Firstly, the server subsystem is addressed. We calculate the maximum requests admitted and the required buffer size of a storage server. Then, an admission control mechanism for the storage server is proposed. Secondly, the network subsystem is discussed. An M/G/1 vacation model is constructed to analyze the FDDI-II network. We investigate the proportion of circuit-switched service, the length of operating target token rotation time, and the fraction of synchronous frame service time that have the impact on the network queueing delay. Then, the strategies of FDDI-II network parameter setting are suggested. Finally, the display subsystem is analyzed. The Video Buffering Verifier (VBV) corresponding to constant rate coded video bit streams is studied. We propose an algorithm to compute the VBV buffer size and the initial VBV delay. Some principles about the picture configuration of a video stream are recommended.