Abstract: In order to reduce the coding computation complexity of the DCT（Discrete Cosine Transform） and quantization module，an innovative algorithm is presented for detecting all-zero DCT coefficient blocks（AZB） prior to DCT and quantization，which is based on the analysis of the predetermination AZB theorem，DCT coefficients distribution models and the characteristics of H.264/AVC integral DCT transform and quantization.Furthermore，with analysis of the most optimal matching block search and mode selection，this algorithm is applied to early termination of both motion-estimating and mode selecting.The extensive experiments results show that the number of searching points when employing the proposed new early termination algorithm can reduce much more than applying the existing algorithms.

Key words: complexity reduction, Laplace distribution, all-zero block detection, early termination of motion-estimation and mode-selection

摘要： 针对全零DCT（Discrete Cosine Transform）系数块，为避免对其进行变换和量化操作以减少编码器的运算量，基于全零块预判的本质，根据DCT系数分布的特性，结合H.264/AVC整数变换和量化的特点，提出了一种预先判断全零DCT系数块的新方法。同时，针对H.264/AVC高精度运动矢量和多编码模式的高复杂度，通过分析最佳匹配块搜索的本质，提出了基于全零DCT系数块预判准的运动估计和模式选择早结束算法。实验结果表明，与已有基于全零块准则的快速运动估计算法相比，其实际搜索点数均有较明显的减少。

关键词: 复杂度降低, 拉普拉斯分布, 全零块预判, 运动估计及模式选择早结束