The Research And Embedded Application Of H.264 Coding Algorithm

ISO(International Organization for Standardization) and ITU(International Telecommunication Union) work together to work out a new video coding standard-H.264,in order to obtain better compression and transmission performance.The H.264 standard introduction the new technologies of current video encoding,including multi-slice size model, 4×4 integral transformation, intra prediction, the effect of filtering to block, entropy coding of the reunification and so on.Compared with other video coding standard of existing,the new technology allows H.264 coding standard can get a higher compression ratio and better image quality in the same circumstances. So,it has good application prospect.With a broad application of embedded systems, Implementation the video codec in the embedded systems has become the focus and difficult one of H.264 study.In this paper, on the basis of detailed analysis of H.264 coding theory,study the campaign estimates and choose the mode of algorithms of a high degree of complexity , and then accomplishment real-time video capture encoding system based on H.264 in the PXA255 of embedded platform.Firstly,Under familiar the theory of video encoding premise, introduce the structure and level of the H.264 encoder,and multianalysis the key technology and encoding performance of H.264. Comparison of H.264,MPEG2,MPEG4 and H.263 encoding performance from two aspects of subjective and objective.From the test results, H.264 has better coding performance both the aspect of subjective or objective.Secondly,detailed analysis of search algorithm of the motion estimation,and compared the performance of several search algorithm. The results show that the whole search has the best search performance, but a high degree of complexity.So,not suitable for application in practice.But,The fast algorithm of three-step search,diamond Search,hexagonal search algorithm and mixed asymmetrical multi-hexagonal search algorithm can greatly improve search speed Without a serious change in search performance.Thirdly,emphatic study mode selection of rate distortion optimization algorithm based on Lagrangian,and increase speed of mode selection by improvement the rate distortion optimization algorithm.The results show that the improved model algorithm can save time large degree,moreover without impact the coding performance major.Finally, H.264 encoding algorithmapplication on PXA255 of embedded platform to accomplishment real-time video capture encoding system based on embedded linux. X264 of H.264 encoding software will be transplanted to PXA255 to achieve the collection of video compression,and optimize the encoding software.Experimental results show that the encoding software of optimization can accomplishment of the basic real-time video encoding for collection video.