低位元率視訊傳輸系統設計與應用

Abstract

本論文將提出與探討一新發展出之視訊壓縮與傳輸系統之差動脈衝編碼調變﹙Differential Pulse Code Modulation﹔DPCM﹚架構與低位元壓縮率之設計與最佳化，並探討其傳輸通道雜訊免疫強度與網路傳輸品質保證等相關問題。 為了克服無線通訊的低頻寬限制，本論文提出一個以三維多項式近似編碼﹙3D Polynomial Approximation Coding﹚為技術基礎的視訊壓縮編解碼系統。該系統保留了MPEG規格所慣用的的DPCM架構，並由Coefficient Generation、Surface Generation、Cube Prediction、Cube Compensation、Thresholding、Residual Coding等模組所構成。依數據與影像主觀測試之實驗結果觀察得知，該壓縮系統表現可優於MPEG-2，且壓縮後之傳輸位元率可低至符合無線通訊傳輸應用之標準，如GSM與Wireless LAN。 本論文探討中，更進行了有關三維多項式近似編碼視訊傳輸系統之於頻道雜訊抵抗能力良劣之模擬與評估工作。藉著數位通訊系統之設計輔助軟體COSSAP﹙COmmunication System Simulation Analysis Program﹚，許多通道編碼技術已被模擬與討論，諸如：二元相位移鍵﹙BPSK﹚、差動四元相位移鍵﹙DQPSK﹚、高斯最小相位移鍵﹙GMSK﹚、以及十六點與六十四點之四元振幅調變﹙16- & 64-QAM﹚。雜訊數據分析與影像視覺主觀分析皆顯示本系統所編碼之視訊，在經過了不同的調變通道傳輸後，解碼結果表現可優於MPEG-2與H.261。 本論文最後將針對此視訊壓縮與傳輸系統之服務品質保證﹙Guarantee of Quality of Service﹔QoS﹚提出探討，而所有的分析與討論由觀察一個應育了WinSock與TCP/IP、建構於個人電腦網際網路上之實驗性軟體視訊傳輸平台所開始。研討中顯示，三維多項式近似編碼視訊壓縮編解碼系統擁有著良好的傳真度﹙Fidelity﹚與敏捷度﹙Agility﹚，可見此低位元率視訊編碼演算法深具QoS發展之潛力與實力。

A block-based non-standard low bit rate video compression algorithm, which can be applied to wireless transmission such as GSM and Wireless LAN, is newly derived and developed. Utilizing 2nd-order polynomial approximation coding techniques, all individual frames along with the time dimension are regressively approximated at the same time to achieve the higher compression ratio. In addition to surveying of the current status of the video technology, both the two- and three-dimensional mathematical model of this compression scheme, along with their DPCM system and the details of each processing module, are describe, discussed and illustrated. The applicable and appropriate subjective examples demonstration and analysis of compression loss in term of PSNR statistics are also provided. What is more, with the aid of COSSAP, which is a CAD software for digital communication from HP/Agilent, various channel, modulation techniques and noise models are simulated to observe the source coding and data transmission performances. Finally, a simple experimental video transmission platform over TCP/IP is constructed to investigate the features for guarantee of quality of service development of this video compression and transmission system. Besides the satisfactory performance for low bit rate video compression, this newly derived and developed video coding system also possesses excellent channel noise immunity and the distinguishing features for assurance of QoS. There is little fulfillment of electronic circuit implementation for this video coding system in this work. As to the software realization, it depends the sufficiently powerful computation capability of a workstation or personal computer to present the real-time-ness of the encoding/decoding along the transmission. Thus this video coding system currently is not good for mobile communication facilities. What is more, those electronic circuit-related characteristics, such as power dissipation and system hardware processing time, can not be quantitatively and subjectively analyzed and discussed yet. ABSTRACT ACKNOWLEDGMENT CONTENTS LIST OF FIGURES LIST OF TABLES 1 INTRODUCTION 1.1 General Concepts for Block Image Coding 1.1.1 Polynomial Regression Technique 1.2 An Overview on the Development of MPEG Standards 1.3 Client/Server Architecture with TCP/IP 1.4 Thesis Overview 2 TWO-DIMENSIONAL POLYNOMIAL APPROXIMATION CODING FOR IMAGE TRANSMISSION 2.1 Two-Dimensional Polynomial Approximation Coding Algorithm 2.2 Encoding Algorithm and System Architecture 3 THREE-DIMENSIONAL POLYNOMIAL APPROXIMATION CODING VIDEO CODEC 3.1 Three-dimensional Polynomial Approximation Coding Video Codec model 3.2 Three-dimensional Polynomial Approximation Coding Video Codec Algorithm 3.2.1 Coefficient Generation a. Computational Simplification b. Buffer Cost Reduction c. Flowchart of Coefficient Generation 3.2.2 Cube Prediction a. Gray Level Transition b. Cube Prediction Algorithm b.1 Direction decision b.2 Prediction c. Flowcharts of Cube Prediction Algorithm 3.2.3 Thresholding 3.2.4 Residual Coding 3.3 Three-dimensional Polynomial Approximation Coding Video Codec Performance Simulation and Analysis 4 ON THE WIRELESS CHANNEL ROBUSTNESS OF 3DPAC VIDEO CODEC 4.1 3DPAC Video Codec Development for Wireless Transmission 4.1.1 Motivation 4.1.2 Primary Development 4.2 Channel Robust Analysis in the Appliance of 3DPAC Vcodec 4.2.1 Theoretical Noise Analysis 4.2.2 Channel Simulation Environment 4.2.3 Simulation Results and Data Analysis 5 ON THE QUALITY OF SERVICE PROVISION OF THREE-DIMENSIONAL POLYNOMIAL APPROXIMATION CODING VIDEO CODEC 5.1 Introduction 5.2 Three-dimensional Polynomial Approximation Coding Video Transmission Experimental Platform with QoS Provision 5.2.1 QoS Principles for the Experimental Platform a. Transparency b. Separation c. Performance/Implementation General Rules Subsumption 5.2.2 Design of the Experimental Platform 5.2.3 Performance of the Experimental Platform a Fidelity b Agility 6 CONCLUSION APPENDIX BIBLIOGRAPHY