整数DCT变换中变换基的通用生成算法

The Generic Generating Algorithm for Integer DCT Transform Radix

H.264是ITU与ISO联合共同开发的具有高编码效率、高压缩质量的视频新标准。整数变换是其提高压缩性能最主要的改进方法之一,基于同样的整数变换过程的变换基可以不唯一,因此在整数变换的理论确定后,寻找变换基是一件重要的工作,提出了一种通用的变换基生成算法。该方法通过分析整数DCT变换的原理,指出了整数变换矩阵应该满足的4个约束条件,以满足正交性约束为出发点,导出了整数矩阵元素之间的数量关系,并辅以另外3个约束条件,采用搜索的方法寻找变换基。实验结果表明,该算法在经过几十步的搜索后,就能找出所有可用的变换基,JVT参考模型用到的变换基也在其中。

H.264 is the new video coding standard established by ITU and ISO,which has high coding efficiency and high compression quality. Integer DCT transform is one of the main renovation for compression efficiency improvement. For the integer DCT radix cannot be the unique within the same transform framework,finding the radix is another valuable research topic besides integer DCT theory. A generic generating algorithm for integer DCT transform radix is presented in this paper. Based on the mathematic analysis of integer DCT transform principle, four constraint conditions which shall be met by integer DCT transform matrix are given first. And then,starting from orthogonal constraint,the magnitude relation of matrix elements is formulized. The formulation, which combines the other three constraint conditions, results in a transform radix finding method by using search strategy. The simulation results show that,only through tens of seeking steps, the proposed method can find all valid radix including the one used by JVT reference model.