摘要
H.264是ITU-T和ISO／IEC联合制订的最新国际视频编码标准，其中众多新颖的算法特性大幅度提高了编码性能，同时运算复杂度也较其他视频标准有巨大增长。如何尽量在保持H.264编码性能的基础上，减少其运算复杂度和提高运行速度，是H.264能否实际应用的关键问题。
本文论述了H.264编码原理，以及它的主要功能模块和采用的一些新技术。针对H.264中树状结构运动估计的特点，利用动态的退出阈值和子集比较预测法，提出了一种快速帧间块模式选择算法；为了更加精确的选择搜索初始点和确定搜索区域，提出了一种基于中心偏向的自适应运动矢量预测算法；结合帧间编码提出全零系数块预先判决算法，通过计算的SAD值来判断是否为零块，减少DCT变换和量化的次数。实验测试表明，在基本上不降低图像质量的情况下，新算法使得编码速度得到了很大提高。
最后，对H.264视频编码的进一步发展和研究提出了自己的一些看法。
H.264 is the newest international video coding standard, joint developed by ITU-T and ISO/IEC, a great many of novel algorithm components enhance the coding efficiency significantly, while dramatically increase the computational complexity than the previous standards. How to reduce its complexity and accelerate the execution speed while maintaining the outstanding compression performance is a crucial problem in the H.264 application.
In this thesis, the encoding principle of H.264 and its main function modules and new technologies being adopted are introduced. A fast block mode selection algorithm focusing on the tree structured motion estimation is proposed in H.264, successive selecting a proper inter block mode fast by a dynamic threshold and subset comparison prediction. And then a new adaptive prediction algorithm for motion vector based on the central trend is proposed for getting more accurate motion estimation point and more appropriate searching fields. At last an algorithm about decision of all-zero blocks is proposed by calculating the SAD, so that decrease the scalar of interger transform and quantization with inter code. Experimental results show that, the proposed methods can improve the coding speed and the capability of encoding loses quite little.
Some ideas for the new development and research of H.264 video coding are proposed at last.
引文
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