| TV weapon guidance is one of the widely used accurate weapon guidance modes in the modern war, which is based on the real time transmission of the video signal. Analog video signal is used by the conventional TV guidance system during the transmission, which needs wide bandwidth and is prone to interference. Furthermore, the hardware of the system is complicated and voluminous, which cannot easily be standardized. Employing digital TV guidance system is a way to solve this problem. However, there exists a great conflit between high data rate of the digital video signal and limited bandwidth of the channel during the real time transmission, which can be solved by video compression technique. Therefore, the research of the video compression system with high fidelity, large compression ratio, low delay is of great theoretical significance and application value, and is also an urgent task in the research and development of the digital TV guidance system.In the conventional video compression methods, Motion-JPEG has low compression efficiency and MPEG has high delay. While being a new gerneration video coding standard, H.264 is more suitable for the application to TV guidance for its high efficienct coding with low delay. In this thesis, the key techniques of H.264 video compression are studied to implement an image processing system for TV guidance. After the technique frameworks of many image and video coding standards are summarized, the comparison of them is also conducted. And especially the framework and principle of H.264 are analysed, focusing on the key module of intra-/inter- prediction, DCT transform and quantization, and entropy coding. It establishes a solid theoretical foundation for hardware design and realization.Texas Instruments's TMS320DM642 DSP is specially designed for multimedia signal processing. DM642 with high CPU frequency has rich resources on the chip. The main research of the thesis is to design and realize a real-time dual-core video compression platform based on DM642 processor. On this board DSP and FPGA cooperate to capture video sequence, compress it using H.264 algorithm, and then transmit the code stream. In the receiver, DSP decompresses and displays the video sequence on the monitor. In the meantime,the circuitry contains Ethernet, VGA and PC104 interface, it can work on target tracking, pattern recognition and classification, so the system has a feature of versatility and extensibility. On the basis of the normal operation of the system, the thesis also does an optimization on system-level, function-level and sentence-level respectively. Finally the system can compress CIF image at the rate of 20 frames per second that meets the requirement of real-time video compression. The system can achieve PSNR of 33.72dB and good restoration images, at the compression rate of more than 20.Fast intra- and inter- frame prediction algorithm for image compression system is one of the key techniques of H.264. The thesis has conducted an in-depth analysis on existed algorithm theory for intra- and inter- frame prediction. To meet the needs of the fast prediction, the thesis does plenty of research based on the search algorithm. Proved by the simulation on PC programs, the modified algorithm improves much in the image compression efficiency and quality of the restoration results. |
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