HEVC快速帧内模式和深度决策算法

Fast Intra Mode and Depth Decision Algorithm for HEVC

针对HEVC帧内预测过程计算复杂度较大的问题,提出基于隔点模式抽取、像素梯度统计和子PU残差相对比的快速帧内预测算法.对应HEVC的33种帧内角度模式,按区间划分33类梯度方向并计算PU各个像素的梯度方向.先对偶数编号的角度模式计算排序,再快速比较得到候选模式集.然后根据所属各类梯度方向的像素累计个数,舍弃部分候选模式.在计算当前PU的哈达玛变换预测残差(Sum of Absolute Transformed Difference,SATD)的同时,记录该PU内4个子PU的SATD,并通过对这4个SATD之间的相对比,跳过当前PU之后深度的计算.实验结果表明,与HEVC标准测试模型HM13.0的算法相比,本文所提出的算法可节省约54%的帧内编码时间,而码率只有约1%的增加.

A fast algorithm based on interlaced extracting modes, statistics of pixel gradient and residual of sub-CU for intra prediction in High Efficiency Video Coding （HEVC） is presented in this paper. Corresponding to 33 intra angle modes in HEVC, gradient directions are divided into 33 classes. And gradient direction of every pixel in a CU is calculated. Angle modes with even number are calculated and ranked firstly, then the set of candidate mode is gained by fast comparison. According to the cumulative number of pixels in every class of gradient direction, some candidate modes can be rejected. When cal- culating Hadamard Transform predicted residual （SATD） of current PU, SATDs of the four sub-PUs are noted. According the relative ratio of them, the traversal calculation of next depth of current PU is rejected. Experimental results show that, compared with HM13.0, the proposed method performs about 54% time saving of intra encoding with only 1% increment on the total rate.