Research On Motion Estimation Algorithm In Video Coding

With the fast develop of multimedia techniques, there are many areas need more efficient real-time compression techniques for digital image processing. Fast compression algorithm is the key for this problem. H.264 is the current project of the ITU-T Video Coding Experts Group (VCEG) and the ISO/IEC Motion Picture Experts Group (MPEG). Although H.264 follows the hybrid coding scheme in common with earlier standards, improvements are achieved through the inclusion of a number of new features that distinguish itself from all existing ones, including Intra Prediction, Integer transform, different predicted block, muti-conference frames, CAVLC,CABAC, quarter-pel precision prediction, Deblocking filter, R-D mode strategy, etc. The being finished Chinese audio and video coding standards AVS has approximate coding efficiency as H.264, AVS's advantages includes high performance, low complexity , low implementation price and sample licensing.Motion Estimation is a key technique for video coding. This thesis is concerned with the Motion estimation techniques of H.264&AVS and proposes improved methods in several fields. UMHexagonS for Fast Integer Motion Estimation is adopted in previous JVT and AVS meetings because it achieves a very good trade-off between ME acceleration and R-D performance. This thesis present some characters within UMHexagonS process and makes corresponding improvements. Compared with the original technique, 30~90% ME time is reduced while the limited performance lose about 0.03dB. AVS applied the variable block sizes and quarter-pel motion compensation to improve coding efficiency. In this paper, an adaptive range fractional pel search algorithm is proposed to further speed up the encoding process and reduce the computation complexity. Small diamond search and threshold judgment are used to this algorithm. Compared to the half-pel full search algorithm, experiments show that the proposed algorithm can reduce the sub-pel search point by 30.25% on average with the limited performance lose about 0.0093dB.With the developonent of the digital audio and video industry, embedded video compression technology is applied more widely. This thesis describes the optimization techniques for a general video encoder based on TMS32DM642 DSP. The algorithm optimization, memory distribution, EDMA and TI's function libraries usage are discussed based on DM642. And the optimization technique for the PMVFAST Fast Integer Motion Estimation base on MPEG-4 are provided. An MPEG-4 encoder based on DM642 using these methods which encodes images of CIF can carry out real-time encoding with 40fps.