Study On Fast Intra Prediction Mode Combinational Algorithm Based On Macroblock Judgement

H.264/AVC is the newest generation video encoding standard,which is widely used in video communication fields.In order to improve coding efficience,H.264 uses Rate distorition optiminzed(RDO)technology to choose the best prediction mode.It reduces space redundancy effectively,but increase coding time and computational complexity,so H.264 can not satisfy the real-time requirement.Therefore under the premise of ensuring video quality and compression efficiency,how to minimize the computation complexity becomes the trend of video coding standards.This paper focuses on the study of intra prediction,the main work are as follows:1.Backgrouds and significance of intra prediction mode selection in H.264 video coding were first introduced,to simplify the computation complexity of existing intra predicition mode selection algorithm,a fast intra prediction mode selection combination algorithm based on macroblock judgement was proposed in this paper.This algorithm combined macroblock pre-judement algorithm and improved the edge histogram Pan algorithm,2.Based on the feature of coding macroblock,the Mean Absolute Difference(MAD)value and Quantization Parameter(QP)set the threshold to judge the smoothness of macroblock,prejudge the macroblock type.Then used a low-complexity three points gradient operator to obtain edge orientation,and the improved Pan algorithm was used to filter the pre-determined macroblock,DC mode can be judeged firstly;Finally,an optimal prediction mode can be determined by RDO technology.3.Under the same coding parameters as the standard test model JM8.6,six different Quarter Common Intermediate Format(QCIF)video sequences were selected to verify the effectivenss and accuracy of this combinational algorithm.The combinational algorithm and full search algorithm,Pan algorithm were compared between coding time?bit rate?PSNR and computational complexity.The experimental results indicate that:(1)The average coding time of predicting algorithm decreased by 11.23%,and the accuracy of the predetermined macro block is 90.5%.(2)This algorithm Compared with the full search algorithm,the coding time is reduced by about 72.4%while the bit rate was increased by 4.21%;Compared with the Pan algorithm,the coding time is reduced by 28.6%,while the bit rate was increased by 1.8%respectively,and the PSNR was invariable.(3)The RDO calculation of the combination algorithm is obviously lower than that of the full search algorithm and Pan algorithm and the computational complexity is reduced.