一种快速H.264帧内模式选择算法

A Fast Algorithm of H.264 Intra-Modes Decision

H.264帧内预测计算复杂,是帧内编码中的瓶颈问题。根据H.264多模式帧内预测特点分析,提出了一种基于纹理和参考像素特性的帧内预测快速算法。算法首先通过Prewitt算子计算得到图像的纹理,根据纹理方向选择相应的帧内预测模式,然后计算参考像素的差异特性,删除已选Intra4x4模式中不必要模式,减少候选模式数目,降低了计算复杂度。对4组不同运动特点序列仿真结果表明:与JM13.2算法相比,本文算法编码时间平均降低75.7%,而图像峰值信噪比平均降低0.16dB,输出码率平均增加3.45%,综合性能优于已有算法。

Computation of H.264 Intra prediction is complex,which is the bottleneck of intra-encoding.After analyzing the features of multi-mode prediction,a fast algorithm is proposed,which is based on the block texture direction and characteristics of reference pixel.First,Prewitt operator is used to estimate block texture directions,and according to these directions corresponding prediction modes are decided.Then the differences of the reference pixel are calculated,and then unnecessary modes of Intra4x4 are deleted.The number of prediction modes and algorithm complexity are reduced effectively.The simulation results on four video sequences with different characters show that,compared with the H.264 JM13.2 encoder,the proposed algorithm can reduce average coding time by 75.7% while decreasing average PSNR by 0.16dB and increasing average bit rate by 3.45%.Its performance is better than the previous algorithms.