HEVC (High Efficiency Video Coding) as one of the newest international video coding standard, can achieve about 50% bit rate reduction compared with H.264/AVC (Advanced Video Coding) with the same perceptual quality by the use of flexible CTU (coding tree unit) structure, but at the same time, it also dramatically adds its computational complexity for HEVC. To reduce the computational complexity, a fast intra-prediction mode and CU (Coding Unit) size decision algorithm based on prediction mode and coding bits grouping is presented for HEVC intra-encoding in this paper. The contribution of this paper lies in the fact that we successfully use the prediction mode grouping and coding bits grouping technologies to rapidly realize the optimal prediction mode and size decision for the current CU, thus saving much computation complexity for HEVC. Specifically, in our scheme, first, we use grouping technology to group 35 intra-prediction modes into 5 subsets of candidate modes list according to the texture complexity of current PU (Prediction Unit), and each subset only contains 11 intra-prediction modes, which can greatly reduce the traversing and calculating number of candidate mode in RMD (Rough Mode Decision); second, we use coding bits grouping technology to quickly judge whether the current CU needs to be further divided on the basis of the studying of texture complexity in the current CU, which can reduce many unnecessary prediction and partition operations for the current CU; at last we use the fast intra-mode prediction and CU size decision algorithm above to quickly realize the optimal encoding for the current CU in HEVC. As a result, the high computational complexity in HEVC intra-encoding can be efficiently reduced by our proposed scheme. And the simulation results of our experiments show that our proposed fast intra-coding algorithm based on prediction mode and coding bit grouping in this paper can reduce about 49.10% computational complexity on average only at a cost of 0.92% bit rate increase and 0.065 db PSNR decline compared with the standard reference HM16.1algorithm under all-intra-configuration.

HEVC（高效视频编码）是最新的国际视频编码标准之一，通过使用灵活的CTU（编码），与具有相同感知质量的H.264 / AVC（高级视频编码）相比，它可以实现约50％的比特率降低树单元）结构，但同时也大大增加了HEVC的计算复杂度。为了降低计算复杂度，本文提出了一种基于预测模式和编码比特分组的快速帧内预测模式和CU（Coding Unit，大小）决策算法，用于HEVC帧内编码。本文的贡献在于，我们成功地使用了预测模式分组和编码比特分组技术来快速实现当前CU的最佳预测模式和大小决策，从而节省了HEVC的大量计算复杂性。具体来说，在我们的方案中，首先，我们使用分组技术将35种帧内预测模式根据当前PU（预测单元）的纹理复杂度分组为候选模式列表的5个子集，每个子​​集仅包含11种帧内预测模式，可以大大减少RMD（Rough Mode Decision）中候选模式的遍历和计算次数；其次，在研究当前CU的纹理复杂度的基础上，采用编码比特分组技术快速判断当前CU是否需要进一步划分，可以减少当前CU的许多不必要的预测和划分操作。最后，我们使用上面的快速帧内模式预测和CU大小决定算法快速实现HEVC中当前CU的最佳编码。结果是，我们提出的方案可以有效降低HEVC帧内编码的高计算复杂度。实验仿真结果表明，本文提出的基于预测模式和编码比特分组的快速帧内编码算法，仅以增加0.92％的比特率和0.065db的PSNR为代价，平均可以减少约49.10％的计算复杂度。与所有内部配置下的标准参考HM16.1算法相比，它的下降幅度更大。