motion estimation and compensation for very low bitrate video coding

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22 Chapter 1. Digital Video Coding at Very-Low BitRate CC Video in T Q P -1 Q -1 T T Transform Q Quantizer P Picture Memory with motion compensated variable delay CC p t qz q v Coding control Flag for INTRA/INTER Flag for transmitted or not Quantizer indication Quantizing index for transform coefficients Motion vector 1.4.1.1 Intra Macroblocks Figure 1.3: H.263 encoder p t qz q v To video multiplex coder H.263 is part of the transform coding class (Chapter 10 of [113]) of algorithms. The macroblocks to be intra coded are linearly transformed by the Discrete Cosine Transform (DCT, [2]) that decomposes the signal into its di erent frequency components. Every coe cient is then separately quantized and the set of coe cients is entropy-coded. The DCT is applied to blocks of 8 8 pels, i.e. a macroblock is made out of four DCT blocks for the luminance and two DCT blocks for the chrominance
1.4 Some (Very-) Low BitRate Codecs 23 Picture MB DCT Motion Residual Change type type coef. vector coding quant. Intra Intra Intra Intra Intra Stu ng Inter Intra Inter Intra Inter Inter Inter Inter Inter Inter Inter Stu ng Table 1.2: Macroblock types and included data elements in H.263 component (one for Cb, one for Cr). The quantization matrix applied to the frequency-based matrix of coe cients can be regularly updated during the encoding process. There are thus three ways of transmitting an intra macroblock, as illustrated in the three rst lines of table 1.2. \Stu ng" means that the macroblock remains exactly the same as in the previous frame. 1.4.1.2 Inter Macroblocks and Residues In inter mode, a motion vector is rst searched for so as to determine the origin of the macroblock. It is achieved by a Block Matching Algorithm (BMA, cf. Section 2.5.1). Then, according to the relevance of the result, the macroblock is either coded in intra mode or via the motion vector and (possibly) additional residues: one of the inter picture modes of table 1.2 is selected. In the case of inter coding with residues, the DFD is coded as an intra macroblock with the DCT. 1.4.1.3 Options In addition to this basic algorithm, four options can be used to improve the quality of the decoded images (with the same bitrate). Each option may be used separately or in combination with some others. The options are: Unrestricted motion vectors: the BMA can select vectors that locate the origin of a MB out of the reference image. The last line
Page 1: LABORATOIRE DE TELECOMMUNICATIONS E
Page 5: Avant-propos Mener a bien une these
Page 8 and 9: Resume L'estimation du mouvement re
Page 10 and 11: x 2.1.1 Apparent versus Real Motion
Page 12 and 13: xii A VLBR-like video sequences 167
Page 14 and 15: 2 Introduction Ancient Greece initi
Page 16 and 17: 4 Introduction Meanwhile, the desir
Page 18 and 19: 6 Introduction However, one can que
Page 20 and 21: 8 Introduction compensation in a vi
Page 22 and 23: 10 Introduction Once the proposed s
Page 25 and 26: Chapter 1 Digital Video Coding at V
Page 27 and 28: 1.2 Video Coding 15 These di erence
Page 29 and 30: 1.2 Video Coding 17 { The redundanc
Page 31 and 32: 1.2 Video Coding 19 exhaustive use
Page 33: 1.4 Some (Very-) Low BitRate Codecs
Page 37 and 38: 1.4 Some (Very-) Low BitRate Codecs
Page 49: 1.5 Discussion 37 1.5 Discussion Th
Page 52 and 53: 40 Chapter 2. Motion in the Framewo
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72 Chapter 2. Motion in the Framewo
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78 Chapter 3. Multiscale Block Matc
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Chapter 4 Image Pre-Processing for
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4.1 Intuitive Rationale 97 (a) (b)
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4.1 Intuitive Rationale 99 (a) (b)
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4.2 Rate Distortion Conditions 101
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4.3 Experimental Results 107 Pre-pr
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4.3 Experimental Results 109 Mean P
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4.3 Experimental Results 111 From t
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4.3 Experimental Results 113 Origin
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4.4 Conclusion 119 4.4 Conclusion T
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122 Chapter 5. Mesh-Based Motion Co
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162 Conclusion so as to adapt the s
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164 Conclusion gain is not as obvio
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Appendix A VLBR-like video sequence
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VLBR-like video sequences 169 Coast
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Appendix B Rate Distortion theory A
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B.1 Information Theory 173 B.1 Info
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B.2 Discrete Memoryless Sources and
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B.3 Rate Distortion Function 177 B.
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B.4 Extension to Moving Pictures 17
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B.4 Extension to Moving Pictures 18
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184 Chapter C. Markov Random Fields
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186 Chapter C. Markov Random Fields
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Appendix D Complements to Chapter 5
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D.2 Pseudo-code of the implementati
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Bibliography [1] COST 211ter Simula
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Bibliography 205 [21] E. Decenciere
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Bibliography 207 [41] R.M. Gray. Ve
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Bibliography 209 [65] B. Macq, M.P.
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Bibliography 211 [86] H.G. Musmann,
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Bibliography 213 [110] M.P. Queluz
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Bibliography 215 [132] F. Vermaut,
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