The Research And Realization Of Video Coding Of H.263 And Digital TV Demultiplex System

With the development and popularization of computer and network technology, video technology has been widely applied to various applications. There is large amount of data in video stream, and the transmission of video stream must be real-time and reliable, so the requirement of reliable transmission in limited bandwidth has accelerated the research and development of video coding technology. H.263 standard is a draft made by ITU-T. With its flexibility and less bandwidth, H.263 has been included into many multi-media communication terminal standards. Recently digital TV is widely known in our society, and the technology in the digital transmission link is the multiplex and demultiplex technology of MPEG-2 transport stream. The automatic quality inspection such as black frame and static frame is needed before program broadcasting in TV station. Based on this application, a digital TV demultiplex system is designed in this paper.The main contents of this thesis are shown as follows.1. On the basic of research on the elementary knowledge and algorithm of H.263 standard, a video coding system is designed in this paper. In the encoding process, the time redundancy is reduced by interframe prediction algorithm, the space redundancy is reduced by DCT algorithm, and the code is compressed by the variable length code (VLC) algorithm.2. Motion estimation algorithm accounts for about 50 to 80 percent of the whole encoding computation. All kinds of block matching motion estimation algorithms are summarized in this paper, and a new fast motion estimation algorithm, named as Modified Hexagon Search, is presented. The new algorithm is based on the correlation and center distribution characteristic of motion vectors. Through predicting the initial search points at first, it adopts a small template at early searching stage and a large template at later stage. Experiments show that the new algorithm increases the coding speed without reducing the coding quality.3. On the basic of research on the MPEG-2 system, a demultiplex system based on directshow is introduced in this paper. The system can demultiplex the MPEG-2 transport stream which contains many programs, and display each program simultaneously. Before displaying the programs, the system can make a quality inspection for black frame and static frame.