基于时空相关性的HEVC帧间模式决策快速算法

新一代的高效率视频编码标准HEVC采用编码树单元（CTU）四叉树划分技术和多达10种的帧间预测单元（PU）模式，有效地提高了编码压缩效率，但也极大地增加了编码计算复杂度。为了减少编码单元（CU）的划分次数和候选帧间PU模式个数，提出了一种基于时空相关性的帧间模式决策快速算法。首先，利用当前CTU与参考帧中相同位置CTU、当前帧中相邻CTU的深度信息时空相关性，有效预测当前CTU的深度范围。然后，通过分析当前CU与其父CU之间的最佳PU模式空间相关性，以及利用当前CU已估计PU模式的率失真代价，跳过当前CU的冗余帧间PU模式。实验结果表明，提出的算法与HEVC测试模型（HM）相比，在不同编码配置下降低了52%左右的编码时间，同时保持了良好的编码率失真性能；与打开快速算法选项的HM相比，所提算法进一步降低了30%左右的编码时间。

Spatio-temporal correlation based fast inter mode decision for HEVC

The new generation high efficiency video coding (HEVC) standard adopts coding tree unit (CTU) quadtree partition technology and ten inter prediction unit (PU) modes to improve compression efficiency significantly, but it brings in an enormous encoding computational complexity. A spatio-temporal correlation based fast inter mode decision algorithm for HEVC was proposed to reduce partition times of coding unit (CU) and inter PU mode candidates. First, the spatio-temporal correlation of depth information among the current CTU, the same located CTU in the reference frame and the spatial neighbor CTU in the current frame are utilized to predict depth range of the current CTU. Then, the spatial correlation of optimal PU modes between the current CU and its parent-CU was analyzed. And the rate-distortion (RD) costs of the estimated PU modes of the current CU were also used. Based on these, the redundant inter PU modes of the current CU are skipped. The experiment results demonstrate that as compared to the HEVC test model (HM), the proposed algorithm saves about 52% encoding time under different encoding configurations, and it maintains a good RD performance. When compared to HM with fast mode decision algorithms enabled, the proposed algorithm further saves about 30% encoding time.