中文摘要：

高性能视频编码（HEVC）是刚确立的最新一代视频编码标准。对于帧内编码,HEVC最大的特点是采用了从64×64至8×8的编码单元划分和35种帧内预测模式,HEVC通过遍历所有的分块和帧内预测模式,选取最优的预测方式,这种帧内预测方式在提高预测精度的同时也大大增加了编码的计算复杂度。为了降低帧内预测的计算复杂度,HM2.0版以上的HEVC测试软件采用一种基于两步预测的快速帧内模式选择算法。在此基础上本文首先提出了一种基于纹理方向的快速粗选方案,减少参与计算的粗选模式数,进而提出基于结构相关的决策方法,利用同质图像区域的纹理相似性,减少参与率失真代价函数计算的候选模式数量,进一步降低了帧内预测计算复杂度。实验结果表明,本文所提出的快速算法,在保持编码质量基本不变的条件下,可以使基于两步预测的快速帧内模式选择时间缩短25。

英文摘要：

The most prominent feature of intra prediction in the High Efficiency Video Coding（ HEVC） is adopting the tree structured coding unit（ CU）,whose size can be changed from 64 × 64 to 8 × 8,and 35 intra prediction modes. Consequently,the intra mode decision process in HEVC is performed using all the possible CU sizes and prediction modes to find the optimal coding mode. This achieves the highest coding efficiency but at the cost of a very high computational complexity. To reduce the computational complexity of intra frame prediction,from the version 2. 0,the HM reference software has adopted an two stage fast intra prediction algorithm. In this paper,an improved fast mode decision algorithm for intra prediction is proposed based on two stage fast intra prediction algorithm to further reduce its computational complexity. Firstly,a rough decision based on the texture direction is exploited to reduce the computational loads of rough mode dicision. Furthermore a refine decision method based structure correlation is proposed to reduce the number of candidates in the rate distortion calculation process by using texture similarity in a homogenous region in order to further reduce the computational loads of intra prediction. Experimental results have demonstrated that compared with the fast intra mode decision method of HM9. 0,the proposed algorithm can save 25 computational time on average with negligible loss of coding efficiency.