CCITT recommendation H.261 video codec implementation Item Type text; Thesis-Reproduction (electronic) Authors Chowdhury, Sharmeen, 1966- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 27/09/2021 19:57:22 Link to Item http://hdl.handle.net/10150/292041 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. 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Contact UMI directly to order. University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road. Ann Arbor, Ml 48106-1346 USA 313/761-4700 800/521-0600 Order Number 1350936 CCITT recommendation H.261 video codec implementation Chowdhury, Sharmeen, M.S. The University of Arizona, 1992 U MI 300 N. ZeebRd. Ann Arbor, MI 48106 CCITT RECOMMENDATION H.261 VIDEO CODEC IMPLEMENTATION by Sharmeen Chowdhury A Thesis Submitted to the Faculty of the DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE WITH A MAJOR IN ELECTRICAL ENGINEERING In the Graduate College THE UNIVERSITY OF ARIZONA 19 9 2 2 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of requirements for an ad­ vanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, pro­ vided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: Date Assistant Professor of Electrical and Computer Engineering 3 ACKNOWLEDGMENTS I would like to express my appreciation to the professors who have contributed to make this work possible. First, I am indebted to my advisor, Dr. Ming-Kang Liu, for his constructive suggestions, guidance, and encouragement. His insightful comments and valuable critic have been very useful in developing this thesis. Also, I like to thank my thesis committee members, Dr. Michael W. Marcellin and Dr. William H. Sanders, for reviewing the thesis. The assistance of J. Chitwood, at the University of Arizona Video Campus, for providing the input images is gratefully acknowledged. Finally, my gratitude goes to my parents and Alvi for their patience, support, and active assistance over the years in many, many ways. 4 TABLE OF CONTENTS LIST OF FIGURES 6 LIST OF TABLES 9 LIST OF ABBREVIATIONS 10 ABSTRACT 13 1. Introduction 14 1.1. Background 14 1.2. Thesis Motivation and Objective 15 1.3. Thesis Outline 16 2. Background of H.261 Standard 18 2.1. Video Input Format 18 2.2. Compression Algorithm 23 2.2.1. Interframe Compensation 23 2.2.2. Motion Compensation 26 2.2.3. Discrete Cosine Transform 31 2.2.4. Zig-zag Scanning 33 2.2.5. Quantization 34 2.2.6. Buffer Occupancy Control 37 2.2.7. Coefficient Coding 38 2.2.8. Frame Reconstruction 40 2.2.9. Compressed Data Output Format 43 2.3. H.261 Decoding 48 3. Program Structure and Software Implementation 50 3.1. Compression Program 50 3.1.1. Program Input and Output 50 3.1.2. Input Conversion 51 3.1.3. H.261 Compression Program Flowchart 52 3.1.4. Various Compression Routines 53 3.1.5. Buffer Simulation 56 5 3.2. Decompression Program 63 3.2.1. Program Input and Output 63 3.2.2. Decompression Program Flowchart 64 3.2.3. Various Decompression Routines 64 4. Results and Discussions 72 4.1. Data Summary 72 4.2. Performance Discussion 80 4.2.1. Buffer Occupancy and Step Size Adaptation 80 4.2.2. Inter Macro Block Percentage, Number of Compressed Bits and Compression Ratio 89 4.2.3. Average Step Size, Average Number of Coefficients and Aver­ age Number of Bits 95 4.2.4. Root Mean Square Error and Signal-to-Noise Ratio 95 5. Conclusions 105 REFERENCES 108 6 LIST OF FIGURES 2.1. Significant Pel Area for Y, U, V 19 2.2. Positioning of luminance and chrominance pixels 20 2.3. Block transformation 20 2.4. H.261 frame structure 22 2.5. Block diagram of H.261 compression method 24 2.6. Characteristic of intra/interframe compensation 25 2.7. Search window and a current block 27 2.8. Block comparison order 27 2.9. Example of 3_step_algorithm 28 2.10. Characteristic of motion compensation 30 2.11. Zig-zag scanning 33 2.12. Quantization characteristics 35 2.13. Step size adjustment and transmission in a GOB 37 2.14. Example of events 39 2.15. Inter and intra macro blocks 40 2.16. Filtering of a basic block with 121 filter 42 7 2.17. Syntax diagram for H.261 video multiplex coder 45 2.18. Macro Block Addressing 47 2.19. Block diagram of H.261 decompression method 49 3.1. Input and output for H.261 coder 52 3.2. Flowchart (part one) for the compression program 57 3.3. Flowchart (part two) for the compression program 58 3.4. Flowchart (part three) for the compression program 59 3.5. Flowchart (part four) for the compression program 60 3.6. Flowchart (part five) for the compression program 61 3.7. Input and output for H.261 decoder 64 3.8. Flowchart (part one) for the decompression program 68 3.9. Flowchart (part two) for the decompression program 69 3.10. Flowchart (part three) for the decompression program 70 3.11. Flowchart (part four) for the decompression program 71 4.1. Original Frame 1 73 4.2. Original Frame 2 73 4.3. Compressed and decompressed Frame 1 at p = 6 74 4.4. Compressed and decompressed Frame 2 at p = 6 74 4.5. Compressed and decompressed Frame 1 at p = 20 75 4.6. Compressed and decompressed Frame 2 at p = 20 75 8 4.7. Group of block rows 78 4.8. Buffer occupancy after every frame 90 4.9. Step size at the beginning of every GOB row 91 4.10. Inter macro block percentage per frame 92 4.11. Total number of compressed bits per frame 93 4.12. Compression Ratio vs. Transmission Rate 94 4.13. Mean value of step size per frame 96 4.14. Mean value of the number of non-zero coefficients per macro block . 97 4.15. Mean value of the number of zero coefficients per macro block .... 98 4.16. Mean value of the number of bits per intra macro block 99 4.17. Mean value of the number of bits per inter macro block 100 4.18. Root mean square error for luminance-Y 101 4.19. Signal-to-noise ratio for luminance-Y 102 4.20. Signal-to-noise ratio for chrominance-U 103 4.21. Signal-to-noise ratio for chrominance-V 104 9 LIST OF TABLES 3.1. Transmission Rate versus Quantization Step Size 54 4.1. Presentation of results at p = 1 and for Frame 1-5 81 4.2. Presentation of results at p = 1 and for Frame 6-10 82 4.3. Presentation of results at p = 6 and for Frame 1-5 83 4.4. Presentation of results at p — 6 and for Frame 6-10 84 4.5. Presentation of results at p = 10 and for Frame 1-5 85 4.6. Presentation of results at p = 10 and for Frame 6-10 86 4.7. Presentation of results at p = 20 and for Frame 1-5 87 4.8. Presentation of results at p = 20 and for Frame 6-10 88 10 LIST OF ABBREVIATIONS CBP Coded Block Pattern CCITT Consultative Committeefor International Telegraphy and Telephony CIF Common Intermediate Format DCT Discrete Cosine Transform DSM Digital Storage Media EOB End Of Block GBSC Group of Block layer Start Code GEI Group of block layer Extra Insertion information GIF Graphics Interchange Format GN Group Number GOB Group Of Block GOBLH Group Of Block Layer Header GQUANT Group of block layer QUANTization GSPARE Group of block layer SPARE information 11 Inter-MVBIT Mean Value of the number of BITs per Inter macro block intra-DC Direct Current term in intra macro block Intra_MVBIT Mean Value of the number of BITs per Intra macro block JPEG Joint Photographic Experts Group LAN Local Area Network LZW Lempel-Ziv Welch decoding algorithm mb macro block MBA Macro Block Addressing MC Motion Compensation flag MPEG Moving Pictures Experts Group MQUANT Macro block layer QUANTization