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Novel Source Coding Methods for Optimising Real Time Video Codecs

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Novel Source Coding Methods for Optimising Real Time Video Codecs NOVEL SOURCE CODING METHODS FOR OPTIMISING REAL TIME VIDEO CODECS A Thesis submitted for the degree of Doctor of Philosophy By Premkumar Elangovan Department of Computing and Advanced Technologies, Faculty of Enterprise and Innovation, Buckinghamshire New University Brunel University, West London July, 2009 ii Abstract The quality of the decoded video is affected by errors occurring in the various layers of the protocol stack. In this thesis, disjoint errors occurring in different layers of the protocol stack are investigated with the primary objective of demonstrating the flexibility of the source coding layer. In the first part of the thesis, the errors occurring in the editing layer, due to the coexistence of different video standards in the broadcast market, are addressed. The problems investigated are ‘Field Reversal’ and ‘Mixed Pulldown’. Field Reversal is caused when the interlaced video fields are not shown in the same order as they were captured. This results in a shaky video display, as the fields are not displayed in chronological order. Additionally, Mixed Pulldown occurs when the video frame-rate is up-sampled and down-sampled, when digitised film material is being standardised to suit standard televisions. Novel image processing algorithms are proposed to solve these problems from the source coding layer. In the second part of the thesis, the errors occurring in the transmission layer due to data corruption are addressed. The usage of block level source error-resilient methods over bit level channel coding methods are investigated and improvements are suggested. The secondary objective of the thesis is to optimise the proposed algorithm’s architecture for real-time implementation, since the problems are of a commercial nature. The Field Reversal and Mixed Pulldown algorithms were tested in real time at MTV (Music Television) and are made available commercially through ‘Cerify’, a Linux-based media testing box manufactured by Tektronix Plc. The channel error-resilient algorithms were tested in a laboratory environment using Matlab and performance improvements are obtained. iii Acknowledgements I would like to take this opportunity to thank my supervisors, Dr Peter Harding and Dr Gaoyong Luo, for their valuable supervision and support all these years. I am grateful to Professor John Boylan for supporting me with the funding necessary to carry out my research. I would like to express my gratitude to Professor Geoff Lawday for linking me with Tektronix and helping take over a commercial project as part of my research. Especially, I would like to thank Tektronix for the support and funding they have provided and for accommodating me in their commercial laboratory for nine months. I would like to thank Dr. Paul Robinson, Dr. Mathew Bowers and Andy Hickman at Tekronix for the generosity shown towards my research project. I would also like to thank Oliver Barton, Sacha Darwin and Dr. Scott Griffiths at Tektronix for their valuable technical assistance throughout the project. I would like to thank Professor Chris Hudson, Dr Peter Wilkinson, Laura Bray, Dr Anne Evans, Howard Bush, William Lishman, staff at Tektronix, staff at Bucks New University and my fellow research students for their help and support. I dedicate this work to my beloved parents Elangovan Chinasamy, Meenalochani Elangovan and my sister Dr Janane Elangovan. iv Author’s Declaration This is to certify that the work submitted in my thesis is my own and has not been submitted for any other degree. Attention is drawn to the fact that some of the preliminary results have been published. Contents of Chapters 3, 4, 5 and 6 have been filed as patents:- • A Method of Quantifying Inter-field Motion in a Video Frame , Copyrights: Tektronix and Danaher Inc (2008). • A Method of Identifying Inconsistent Field Dominance Metadata in a Sequence of Video , Copyrights: Tektronix and Danaher Inc (2008). • A Method of Tracking a Region of Interest in a Sequence of Video Frames , Copyrights: Tektronix and Danaher Inc (2008). • A Method of Determining Field Dominance in a Sequence of Video Frames , Copyrights: Tektronix and Danaher Inc (2008). • Video Type Classification Copyrights: Tektronix and Danaher Inc (2008). Contents of Chapters 7, 8 and 9 have been published in conferences:- • Optimizing Video Codecs for Mobile Multimedia Applications , 3rd IET European conference on Visual Media Production , pp 182, London, (2006). • Structurally Efficient Video Codec for Wireless Mobile Applications , 4th International Conference on Information Technology , pp 190-195, Las Vegas, (2007). v • Source Based Error Protection for Wireless Video by Motion Vector Sharing and Residual Garbaging , IEEE International Conference on Digital Signal Processing , Cardiff, (2007). • Motion Vector Smoothing Algorithm for Robust Wireless Multimedia Communications , IEEE International Conference on Circuits and Systems for Communications, Shangai (2008). P.Elangovan, 2009 vi Contents Abstract.......................................................................................................................ii Acknowledgements....................................................................................................iii Author’s Declaration ................................................................................................ iv Contents ..................................................................................................................... vi List of Illustrations..................................................................................................... x List of Tables ............................................................................................................ xv Abbreviations .......................................................................................................... xvi Glossary..................................................................................................................xviii 1. Introduction...................................................................................................1-1 1.1. Overview......................................................................................................1-1 1.2. Television and Displays...............................................................................1-2 1.3. Video Compression......................................................................................1-5 1.4. Wireless Standards.......................................................................................1-6 1.5. Video Coding Issues ....................................................................................1-8 1.6. Aim and Hypothesis of the Research.........................................................1-11 1.7. Organisation of the Thesis.........................................................................1-13 1.8. Publications and Patents ............................................................................1-14 1.9. Summary....................................................................................................1-14 2. Literature Review........................................................................................2-15 2.1. Introduction................................................................................................2-15 2.2. Television Standards..................................................................................2-15 2.3. Interlaced and Progressive Videos.............................................................2-17 2.4. Video Compression....................................................................................2-20 2.5. Wireless Fading Channels and Models......................................................2-26 2.6. Summary....................................................................................................2-29 3. Video Editing and Transmission Layer Issues and Research Techniques ……………………………………………………………………………...3-31 3.1. Introduction................................................................................................3-31 P.Elangovan, 2009 vii 3.2. Editing layer Errors....................................................................................3-31 3.2.1. Field Reversal Issue ............................................................................3-31 3.2.2. Mixed Pulldown Issue.........................................................................3-37 3.3. Transmission Layer Errors.........................................................................3-40 3.4. Research Techniques .................................................................................3-43 3.4.1. Research Techniques for Editing Layer Issues ...................................3-43 3.4.2. Research Techniques for Transmission Layer Issues .........................3-47 3.5. Summary....................................................................................................3-49 4. Quantifying Inter-Field Motion for Interlaced/Progressive Classification ……………………………………………………………………………...4-51 4.1. Introduction................................................................................................4-51 4.2. Review of Literature, Problem Definition and Chapter Organisation.......4-52 4.3. Frequency Domain Analysis of Interlaced Signals....................................4-54 4.4. Constraints of the Problem ........................................................................4-58 4.4.1. Issue of Spatial In-equality .................................................................4-58
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