ATETS: 针对H.264的自适应提前终止搜索算法

为了解决H.264可变大小块运动估计技术使得运动估计运算量剧增的问题，提出了一种自适应提前终止搜索算法.根据整数DCT变换和量化的特性，通过提前判定全零系数块来终止没有意义的运动搜索过程.利用运动矢量和预测运动矢量之间的高度相关性，采用预测块作为提前终止判决块.使用基于量化步长的自适应阈值以获得最佳性能.实验表明，该算法与已被H.264标准采纳的快速整像素搜索算法(UMHexagonS)结合使用，能够在保证图像质量和编码压缩率的前提下，进一步减少60%左右的搜索点数.该算法对量化步长具有良好的鲁棒性，适用于固定码率的实时应用环境.

ATETS: adaptive early termination search algorithm for H.264

An adaptive early termination search algorithm was proposed to reduce the computational amount of motion compensation in H.264 video coding brought about by the variable block-size motion estimation.According to the characteristics of integer discrete cosine transformation(DCT) and quantization,the coefficient-all-zero block was determined in advance to terminate meaningless search.According to the high correlation between motion vector and predicted motion vector,the predicted block was chosen as early termination block.An adaptive threshold based on quantization step was presented to optimize the performance. Experiments showed that when this algorithm is used with the UMHexagonS fast search algorithm,it can reduce about 60% of search points and keep the quality and compression rate of picture unchanged.This algorithm provides robust performance for quantization step,and it is applicable to the fixed bit-rate real-time system.