於有線電視網路上多工傳送MPEG II節目流與IP封包以獲取統計效益並實現網際網路存取服務

Abstract

本篇論文主要針對MPEG-II標準中所訂定的多工器作效能上的改進。我們 針對隨選視訊服務，提出了一套在MPEG-II多工器上執行、以時間標記為 依據的排程演算法來將起伏變化大的影像節目平順化，期望能讓多工器於 一個固定頻寬的類比頻道中傳送更多的節目，並能降低節目於傳送時所發 生的延遲，進一步改善節目的播放時所產生的中斷現象。但由於此套排程 演算法並不能如預期的增加於一個類比頻道中傳送的節目個數，因此，我 們從影像節目的壓縮過程來著手，探討一種能降低傳送一片影像節目所需 的頻寬的技術，名為編碼轉換。利用此項技術，便能增加於一個類比頻道 中傳送的節目個數。最後，我們介紹此項技術的運作原理、降低此技術的 複雜度的方法，及三種不同複雜度的模型。關鍵字：MPEG-II 多工器、時 間標記、排程演算法、編碼轉換。 In this work, we investigate the methodology to improve performance of the MPEG-II multiplexer. In the video-on-demand (VOD) system, a timestamp-sensitive scheduling algorithm run at the MPEG-II multiplexer is designed to smooth the bursty MPEG-II compressed video programs. By smoothing the MPEG-II programs, we expect to increase the number of programs which can be carried within an analog channel with fixed bandwidth. Moreover, this scheduling algorithm can reduce the delay violation probability and jitter when transmitting video programs. Because the above scheduling algorithm cannot increase the number of transmitted programs, we focus on the compression layer of MPEG-II programs. Another technique called transcoding is introduced. Transcoding technique can reduce bit rate of the MPEG-II compressed video program and the number of programs transmitted within an analog channel can increase. At last, we present the details of the transcoding technique and the way used to reduce the complexity of the transcoder. Besides, three algorithm models of the transcoder are discussed.Keywords : MPEG-II Multiplexer, time- sensitive, scheduling algorithm, smoothing, transcoding.