第18卷第11期 2010年11月
1004-924X(2010)11-2489-08
文章编号
光学精密工程
Optics and Precision Engineering
H.264快速运动估计算法的改进
李桂菊"，刘刚1.2，梁静秋1
Vol. 18No.11
Nov.2010
（1.中国科学院长春光学精密机械与物理研究所，吉林长春130033;2.中国科学院研究生院，北京100039）摘要：为了提高视赖压缩效率，对H.264中采用的快速运动估计算法UMhexagonS进行了改进。首先，在起点预测后加人一个结束搜索条件，判断是否结束对当前宏块的运动估计。然后，对于需要进一步运动估计的宏块，从两个方面对原算法进行了改进。提出了搜索模板分制方法，在进行十字形模板和大六边形模板搜索时，只需要根据该方法选择少量搜索点进行运动估计。根据运动失量的统计特点，减少了正方形模板和扩展六边形模板的搜索点数。同时验证了所采用的搜索区域分割方法的合理性。实验结果显示，改进算法的运动估计时间比原算法平均减少了15.59%，而峰值信噪比
和码率基本不变，并且能够适应各种运动类型的视频序列。得到的结果表明改进算法提高了总体编码性能。关键调：视频压缩；区城分割；UMhexagonS算法；运动信计；航计特点
中图分类号：TN941.1;TP301.6
文献标识码：A
doi;10.3788/OPE.20101811.2489
Improvementoffastmotionestimation
algorithm used in H.264 LI Gui-ju',LIU Gangl-,LIANG Jing-qiu
(l.ChangchunInstituteof Optics，FineMechanicsandPhysics，
ChineseAcademyofSciences，Changchun130033,China
2.GraduateUniersity of ChineseAcademy of Sciences,Beijing 100039,China)
Abstract: A fast motion estimation algorithm used in H. 264,UMhexagonS, is optimized to improve the efficiency of video compression. Firstly, a stop-search technique is used to judge whether the mo tion estimation of current macro block should be stopped after the initial search point is predicted. Then,the original algorithm is improved in two respects for macro blocks which need further motion estimation, One improvement is that fewer search points are used in motion estimation by the pro posed partition method when multi-hexagon-grid pattern or cross pattern are adopted, and the other improvement is that the search points of square search pattern and extended-hexagon search pattern are reduced according to statistical characteristices of motion vectors. Moreover, the rationality of the partition method is proved. Experimental results show that the average time of motion estimation is reduced by 15. 59% compared with that of the original algorithm, whereas, the Peak Signal to Noise Ratio (PSNR) and bit rate remain almost unchanged. The proposed algorithm improves the coding performance and is suitable for various types of video sequences.
收稿日期：2010-01-22；修订日期：2010-04-13.
基金项目：中国科学院知识创新工程领域前沿项目