Research On The Algorithm Of HEVC Intra Prediction Mode Decision

High Efficiency Video Coding(HEVC / H.265)is a new generation of video coding standards.HEVC / H.265 uses a mixed-coded frame structure.And intra prediction is a key technology under the coding framework.Compared with the H.264 / AVC standard,HEVC / H.265 contains up to 35 kinds of intra prediction modes.The intra prediction mode selection algorithm in this standard is to select the best intra prediction mode by three steps.(1)a low-precision rough mode selection(RMD)process for 35 kinds of prediction modes,selecting a part with a larger possible model as a candidate;(2)by selecting the adjacent coded block prediction mode,And then screen out the three models as a candidate.(3)The high-precision rate-distortion optimization(RDO)process is performed by the first two steps,and the best prediction mode is selected.The parameters of the selected best mode will be used for subsequent coding.The process is to filter all 35 prediction modes,which costs a lot of computing time.Therefore,this paper firstly analyzes the principle of predicting the pixel value in the prediction block,and obtains the conclusion that there is correlation between the adjacent prediction modes,and evaluates the result by the rough selection of the test sequence to verify the conclusion.Then,the improved algorithm is used to reduce the number of HEVC intra prediction modes.The improved algorithm can reduce the mode of rough mode selection(RMD)and subsequent rate distortion optimization(RDO)process.So as to achieve the purpose of reducing the complexity of the intra prediction mode selection algorithm.The algorithm proposed in this paper is finally tested on HEVC’s official test software HM13.0.Experiments were performed on 10 test sequences in Class A-Class E.The experimental results show that the coding time is reduced by 18.07% when the average bit rate(BD-BR)is increased by 1.09% and the peak signal-to-noise ratio(BD-PSNR)is reduced by 0.023 d B.At the same time,compared with the same idea coding,this algorithm has improved the average bit rate(BD-BR),peak signal to noise ratio(BD-PSNR)and coding time,Improve the effectiveness of the algorithm.