The Optimization Of H.264 Ⅰ Frame Encoder And Implementation On DSP

H.264/AVC is an international digital video code standard designed by MPEG and VECG which has stronger performance then MPEG4 and H.263.It take the predominant position in all the existed video code standard soon because of it's excellent compression performance and nice network friendness. H.264 may become the first standard to select in the wireless video communication,internet video appilication and HDTV.But in order to gain high compression good coding result, H.264 adopts so many new algorithms that the amount of calculation increase drastically.As a result,it's real-time appilication is restricted.So it is significant for the real-time appilication of H.264 to optimize the encoder and research the fast encode algorithms.Based on the demand of actual item,this paper introduce how to optimize the H.264 encoder and implement the real-time encoder on the DSP.The main content of this paper can be concluded by following:1.Research the H.264 stardard,especially on the intra-prediction and entropy code module,and try to find the way to improve the encode efficiency.2.Based on analyzing kinds of intra-prediction optimizing algorithms,this paper give an improving algorithms both on the selection of block type and the mode of 4x4 prediction.First,we propose an solution which can confirm the type of prediction block beforehand by using the connecting of AC coefficient energe and smoothness of an image.Second,motivatied by the highly correlation between different prediction direction,we use the improving three-step exploring algorithm which can efficiently explores the neighborhood direction around the minimun one and thus skips other unlikely ones.The simulaton result shows that the proposed algotithm can save up 12% of computation time I frame encoder which can maintain the similar PSNR quality to the full search algorithm.3.Implement optimizing method on entropy code module.First,based on the depth analyzing the theory of CAVLC ,this paper propose the simplify method aimming at the JM82 test programme.The simulation result show that it can save up 23.9% of computation time of this module without change the PSNR and the bitrate.Second,based on the thorough analyzing the theory of CABAC module and JM82 test program,we adopt the optimizing method-- rewrite the CABAC in assembly language.4.Transplant the algorithm into DSP platform, optimize the Cache efficience, and save up 26.9% of all I frame encoder.Finally,implememt real-time H.264 I frame encoder successfully which based on D1 format image.