H．263中全零离散余弦变换系数的预先判别

为减少编码器的运算量，对量化后离散余弦变换（DCT）系数全为零的块进行预先判断，从而不对其做相应的DCT变换与量化，提出了预先判断全零DCT系数块的方法，在分析现有判别方法对全零系数块的误判与漏判的基础上，从二维DCT变换的公式出发，给出了误判与漏判的判别准则，并以这一准则为指导，提出了一种在保证不出现误判的条件下减少漏判的新方法，提高了判别效应，给出了具有一般表示的判别式，可以应用于不同尺寸的变换块，同时给出了另一个判别效率更高的经验判别式，实验结果表明，所提供的判别方法提高了全零DCT系数块的判别效率。

Early Detection Method of All-Zero Discrete Cosine Transform Coefficients in H.263

In order to reduce the time for computing in H.263 low bit rate video coding,the blocks whose quantized discrete cosine transform (DCT) coefficients are completely zero are pre determined,and then these blocks are not DCT transformed and quantized.This is the so called early detection method of all zero DCT coefficients (EDMA).Based on analysis of the misjudgment and miss judge of the existing EDMA algorithms, a guideline for the misjudgement and miss judge was provided via the formula of two dimensional DCT.With this guideline,a new approach to pre determine the all zero DCT coefficient blocks with high efficiency was proposed.A generalized discriminant that can be applied to the blocks with different size was provided, and another discriminant with higher judge efficiency was also proposed.The experimental results show that the proposed approaches improve the judge efficiency. They are very useful in the real time realization of the H.263 coding method.