Improvement and optimization of H.264 video codec.

Tang, Kai Lam.Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.Includes bibliographical references.Abstracts in English and Chinese.Acknowledgement --- p.iAbstract --- p.iiContents --- p.ivPublication List --- p.viiChapter Chapter 1 --- Introduction --- p.1-1Chapter 1.1 --- Video Coding --- p.1-1Chapter 1.1.1 --- Temporal prediction --- p.1-5Chapter 1.1.2 --- Transform Coding --- p.1-9Chapter 1.1.3 --- Quantization --- p.1-12Chapter 1.1.4 --- Entropy Coding --- p.1-14Chapter 1.2 --- H.264/MPEG-4 Part 10 --- p.1-15Chapter 1.2.1 --- Overview --- p.1-16Chapter 1.2.2 --- Intra Prediction --- p.1-19Chapter 1.2.3 --- Inter Prediction --- p.1-20Chapter 1.2.4 --- Transform and Quantization --- p.1-23Chapter 1.2.5 --- Entropy Coding --- p.1-25Chapter 1.2.6 --- Deblocking Filter --- p.1-29Chapter 1.3 --- Organization of the Thesis --- p.1-32Chapter 1.3.1 --- Review of Motion Estimation Techniques --- p.1-32Chapter 1.3.2 --- The Proposed Algorithms --- p.1-33Chapter 1.3.3 --- Optimization of the Codec --- p.1-34Chapter 1.4 --- Contributions --- p.1-35Chapter Chapter 2 --- Review of Motion Estimation Techniques --- p.2-1Chapter 2.1 --- Fast Full Search --- p.2-2Chapter 2.2 --- Hybrid Unsymmetrical-cross Multi-Hexagon-grid Search --- p.2-4Chapter 2.3 --- Center biased Fractional Pel Search --- p.2-6Chapter 2.4 --- Enhanced Predictive Zonal Search --- p.2-7Chapter Chapter 3 --- Enhancement Techniques for Intra Block Matching --- p.3-1Chapter 3.1 --- Introduction --- p.3-1Chapter 3.1.1 --- Fundamental Principles --- p.3-1Chapter 3.1.2 --- Variable Block Size Intra Block Matching --- p.3-3Chapter 3.2 --- Proposed Techniques --- p.3-5Chapter 3.2.1 --- Padding --- p.3-5Chapter 3.2.2 --- Modes --- p.3-9Chapter 3.2.3 --- Performance Enhancement Tools --- p.3-12Chapter 3.2.3.1 --- Multiple Best Matches --- p.3-12Chapter 3.2.3.2 --- Adaptive Integer and Sub-pixel Intra Block Matching --- p.3-13Chapter 3.2.4 --- Pseudo Intra Block Matching --- p.3-14Chapter 3.3 --- Proposed Fast Algorithms --- p.3-16Chapter 3.3.1 --- Fast Intra Block Matching Decision --- p.3-16Chapter 3.3.2 --- Skipping some Intra Block Matching Processes --- p.3-18Chapter 3.3.3 --- Early Termination --- p.3-19Chapter 3.3.4 --- SAD Reuse Techniques --- p.3-21Chapter 3.4 --- Experimental Results --- p.3-22Chapter Chapter 4 --- Enhanced SAD Reuse Fast Motion Estimation --- p.4-1Chapter 4.1 --- Introduction --- p.4-1Chapter 4.2 --- Proposed Fast Motion Estimation Algorithm --- p.4-3Chapter 4.2.1 --- Best Initial Motion Vector --- p.4-3Chapter 4.2.2 --- Initial Search Pattern --- p.4-4Chapter 4.2.3 --- Initial Search Process and Search Pattern Improvement Process --- p.4-7Chapter 4.2.3.1 --- BISPCSP Motion Estimation or Refinement Process Decision --- p.4-8Chapter 4.2.3.2 --- ISP Motion Estimation or Refinement Process Decision --- p.4-9Chapter 4.2.4 --- Motion Estimation Process and Refinement Process --- p.4-9Chapter 4.2.4.1 --- Motion Estimation Process --- p.4-9Chapter 4.2.4.2 --- Refinement Process --- p.4-11Chapter 4.2.5 --- Motion Estimation Skip Process for B Pictures --- p.4-12Chapter 4.3 --- Experimental Results --- p.4-13Chapter Chapter 5 --- Development of Real-Time H.264 Codec on Pocket PC --- p.5-1Chapter 5.1 --- Algorithmic Optimizations --- p.5-2Chapter 5.1.1 --- Fast Sub-Pixel Motion Estimation --- p.5-2Chapter 5.1.2 --- Interpolation --- p.5-5Chapter 5.1.2.1 --- Revision of Luma Interpolation --- p.5-5Chapter 5.1.2.2 --- Fast Interpolation --- p.5-8Chapter 5.1.3 --- Skipping Inverse ICT and Inverse Quantization Depends on Coded Block Pattern --- p.5-10Chapter 5. 2 --- Code Level Optimizations --- p.5-12Chapter 5.2.1 --- Merging Loops --- p.5-12Chapter 5.2.2 --- Moving Independent Code outside the Loop --- p.5-13Chapter 5.2.3 --- Unrolling Loops --- p.5-14Chapter 5.3 --- Experimental Results --- p.5-16Chapter 5.4 --- Applications --- p.5-26Chapter Chapter 6 --- Conclusions and Future Development --- p.6-1Chapter 6.1 --- Conclusions --- p.6-1Chapter 6.1.1 --- Enhancement Techniques for Intra Block Matching --- p.6-1Chapter 6.1.2 --- Enhanced SAD Reuse Fast Motion Estimation --- p.6-1Chapter 6.1.3 --- Development of Real-Time H.264 Codec on Pocket PC --- p.6-2Chapter 6.2 --- Future Development --- p.6-3Bibliography --- p.

Efficient Motion Estimation and Mode Decision Algorithms for Advanced Video Coding

H.264/AVC video compression standard achieved significant improvements in coding efficiency, but the computational complexity of the H.264/AVC encoder is drastically high. The main complexity of encoder comes from variable block size motion estimation (ME) and rate-distortion optimized (RDO) mode decision methods. This dissertation proposes three different methods to reduce computation of motion estimation. Firstly, the computation of each distortion measure is reduced by proposing a novel two step edge based partial distortion search (TS-EPDS) algorithm. In this algorithm, the entire macroblock is divided into different sub-blocks and the calculation order of partial distortion is determined based on the edge strength of the sub-blocks. Secondly, we have developed an early termination algorithm that features an adaptive threshold based on the statistical characteristics of rate-distortion (RD) cost regarding current block and previously processed blocks and modes. Thirdly, this dissertation presents a novel adaptive search area selection method by utilizing the information of the previously computed motion vector differences (MVDs). In H.264/AVC intra coding, DC mode is used to predict regions with no unified direction and the predicted pixel values are same and thus smooth varying regions are not well de-correlated. This dissertation proposes an improved DC prediction (IDCP) mode based on the distance between the predicted and reference pixels. On the other hand, using the nine prediction modes in intra 4x4 and 8x8 block units needs a lot of overhead bits. In order to reduce the number of overhead bits, an intra mode bit rate reduction method is suggested. This dissertation also proposes an enhanced algorithm to estimate the most probable mode (MPM) of each block. The MPM is derived from the prediction mode direction of neighboring blocks which have different weights according to their positions. This dissertation also suggests a fast enhanced cost function for mode decision of intra encoder. The enhanced cost function uses sum of absolute Hadamard-transformed differences (SATD) and mean absolute deviation of the residual block to estimate distortion part of the cost function. A threshold based large coefficients count is also used for estimating the bit-rate part