Research And DSP Implementation Of H.264 In The Real-time Video Surveillance

H.264 is the MPEG and VCFG jointly developed video compression coding standard, and its performance is much higher than MPEG-4 and H.263 code, in 2003 by ITU-T adopted and promulgated in the official internationally.The H.264 has effective coding efficiency and network affinity .The H.264 algorithm is extremely complex,however,the encoding time longer.Therefore,how to reduce the computational complexity and improve the encoding speed is the key to achieve real-time encoder.In addition,the H.264 coding computation involved is very large,and ordinary microprocessors is difficult to meet their requirements. Achieved H.264 video encoder with the DSP has important practical significance.This paper has a careful study of existing video coding standard H.264,from the motion estimation search algorithm,and the H.264 encoder in DSP implementation and optimization, and several other aspects ,and gives the final optimized results.Motion estimation in video coding technology in one of the most critical, and its calculation in the calculation of the total volume of the encoder account for a large proportion,70%-80%,thus improving the motion estimation can greatly improve the encoder efficiency.This paper in-depth analysis of the motion estimation,and focus on the video coding standard block matching motion estimation. On this basis,this paper proposes a fast search algorithm for 1/4 pixel–MPDFS (based on the maximum possible direction of the fast search)algorithm.The main idea of the algorithm bases on the search direction of the pixels in different optimal matching point probability of a different,substantially reducing the number of search points to improve the search speed. And experimental results simulated on the MPDFS show that the time of this MPDFS algorithm is less than the full search algorithm of motion estimation by 20% -30%.Then this paper transplants the improved H.264 coding algorithm to DM6446 DSP platform based on DaVinci technology,and selects x264 as the original model of transplantation. And based on x264 encoding in the original source makes a targeted cut, modify, such as modifying data types, data alignment and variable initialization, adjustment variable access methods and storage space allocation, and ultimately transplants it to DSP platform. Optimizaiton is also the focus of real-time video encoding. This paper based on the characteristics of the DM6446 DSP hardware and structure, and learned optimization techniques commonly used in embedded systems,adopt the code flowing design, the using of inline functions, the data package, the rational allocation of the cache, EDMA3 and the compilation of the key modules to achieve a series of linear methods to optimize x264 code.Finally, we have a test on the optimized x264 code.Test results show that it achieves real-time encoding, and meets the needs of the current real-time video surveillance.