【作者】 庞劭勋；

【导师】 易清明；

【作者基本信息】 暨南大学 ， 通信与信息系统， 2007， 硕士

【摘要】 在视频编码系统中，运动估计技术对降低视频序列时间冗余度、提高编码效率起着非常关键的作用。一方面，运动估计的准确程度将决定视频编码效率。另一方面，运动估计算法的复杂度将直接决定视频压缩编码系统的复杂度。因此本文将重点研究基于AVS标准的视频编码中的运动估计技术。本文通过分析视频序列的运动特性，传统经典算法的原理及优劣，提出了一种基于运动矢量预测以及搜索范围自适应的快速搜索算法。该算法针对运动矢量的时空相关性对运动矢量进行预测，使用当前宏块周围四个参考块的平均值作为当前宏块的运动矢量预测值，并以运动矢量预测值所指向位置做为匹配搜索的起始点；而且根据运动矢量参考值的相似程度决定搜索范围。实验结果表明，新算法的搜索速度比全搜索法提高了大约75倍，比菱形法提高了大约4倍；峰值信噪比比全搜索法低约0.35dB，比菱形法高约0.5dB。在速度比菱形法提升许多的情况下，达到了接近全搜索法的性能，非常适于实时应用。更多还原

【Abstract】 In video coding and processing system, motion estimation (ME) plays very important role in eliminating inter-frame redundancy and improving the performance of video coder. On one hand, the accuracy of motion estimation affects the efficiency of the video coder. On the other hand, the complexity of the encoder lies on that of the of motion estimation algorithm. The motion estimation and motion compensation techniques based on AVS is mainly discussed in this paper.By analyzing the motion characteristic of video sequence and the advantages/disadvantages of the classical searching algorithms, a new fast searching algorithm is proposed based on prediction of motion vector and self-adaptive searching area. In this algorithm, the motion vector is predicted by the space/time correlation of the motion vector. The predicted value of current block is equal to mean value of 4 referential motion vectors, and the starting point of the searching algorithm is chosen as it. At one time, the searching area is decided based on the similar class of the reference motion vectors. Experimental results prove that the searching speed of the new algorithm increases 75 times compared with Full Searching (FS) algorithm, 4 times compared with Diamond Searching (DS) algorithm. The PSNR is about 0.35db lower than FS and about 0.5db higher than DS. The new algorithm is suitable for real-time applications because it achieves similar performance compared with FS and much faster than DS.更多还原