The Research Of Fast Intra Coding Algorithm Based On Quadtree Partition In Hevc

HEVC(High Efficiency Video Coding)standard,the new video coding standard,has achieve its goals that approximately have 50%bit rate reduction compared with the previous standard H.264.The high compression ratio of HEVC stadard has provided solution to deal with the high quality video which needs more the required storage space and bandwidth.Although HEVC has a high compression ratio,it brings in the complex recursion quadtree structure,and has given rise to the coding redundancy and increases encoding time.Therefore,this paper devotes to researching the issue of the computational complexity for HEVC Intra Coding,does its best to reduce the encoding time,in the case that the quality of the video is not significantly reduced.The principal results are as follows:(1)proposed the early termination of Quadtree partition algorithm based on the original reference pixel.Through the research of Intra predition results based on the reconstruction reference pixel and the original reference pixel,found that the prediction accuracy based on the latter was improved.The algorithm select original pixels as reference samples to design the early termination of the Quadtree partition.By comparing the corresponding predicted values of large block and its four leaves and combining the left adjacent block,we determinate whether the current block split or not,set the optimal thresholds for judgment.The algorithm helps to skip the computation of rate-distortion cost which is not necessary,and reduce coding time.Experimental result shows that the algorithm can save an average of 25%encoding time compared with the test model,but only with a negligible peak signal-to-noise ratio loss.(2)proposed a fast Quadtree partition algorithm based on adaptive SATD thresholds.Considering the sum of absolute Hadamard transformed difference SATD values reflect the residuals in the frequency domain,we utilize SATD to determine the size of the CU(Coding Unit).During the process of Quadtree recursion partition in each frame video,we select SATD values of the first several units as references to analyze the early pruning and early splitting thresholds,and judge the size of CU in advance;by setting the boundary values associated with the quantization parameter QP,we use the SATD of the CU which is not previously awarded in the previous step to adaptively renew those thresholds.The result shows that the proposed algorithm can save encoding time by 44%on average with only 0.9%BD rate increment compared with the reference software test model.