Research And Implementation Of The Key Technology For Network Video Encoder Based On H.264 Standard

With the development of multimedia and communication technology, a variety of new applications with high image resolution have been taken into practice. With great perspective, realtime video applications are very popular, in which image quality and bitrates are in the dilemma. H.264 video coding standard can solve this intractability problem successfully. However, there is much complexity in the encoding processes of H.264 encoder. Therefore, how to reduce the complexities of encoding process, as well as to speed up the encoder, becomes the keystone of video application, which is hard to achieve. Therefore, this dissertation researches on three aspects of network video encoder, which include the optimizing algorithm in video encoder, DSP hardware speedup and the real-time transfer of H.264 video packets.Firstly, by researching on the optimizing algorithms, we propose an algorithm based on method of elicitation to optimize intra prediction, inter prediction and mode decision. By exploiting spacial or temporal correlation of neighbor macroblocks, as well as distortion of neighbor macroblock, the algorithm speculates that the partition method and prediction mode of current macroblock is similar to its neighbors. The mechanism provided by the algorithm ensures the best match between prediction block and original block. The results of test prove that the algorithm improves the encoding rate with little image distortion.Secondly, our researches focus on high accuracy fix-point arithmetic and DSP hardware speedup of H.264 application. By optimizing the structure of program, improving memory management, and assigning resources properly, we realize optimizations on the program, algorithm and instruction level respectively. High speed data transfers between DSP and peripherals are implemented by EDMA operations. An overlap between data transfers and data processing are introduced by EDMA mechanisms and the flexible configuration of the on chip SRAM of DSP. After the optimization, ALUs, memory and peripherals are sufficiently utilized. The testing results indicate that the high performance of video encoder optimized by DSP optimized algorithms.Finally, we implement RTP protocol based on the network develop kit provided by TI corporation, which includes the configuration and utilization of TCP/IP protocol. Experimental results are given to evaluate the performance of the video encoder. According to the results, our video encoder is considered to be an application with good performance and high reliability.