Research On Digital Video Broadcasting System

Current, broadcasting movies and TVs in the television station has inevitablydeveloped into digital and network age. Broadcasting systems are the last part beforetelevision station program faces to the audience, relating to directly picture quantity andreliability of the program broadcasting. It is a core that television station's digital turn,having become a highlight of research on computer application. For the sake of guaranteethe picture quality of program broadcasting, the key problems such as reliability, frameaccurateness and real-time performance are studied from the hardware architecture, the keyalgorithm and the response time etc. aspect of digital broadcasting systems. The architecture of digital broadcasting systems is the most important issue of buildingthe digital broadcasting systems. Its core is the storage and broadcasting sub-systems, andthe design of architecture of the storage and broadcasting sub-system is a key. For satisfythe high reliability, the high data transfer rate, the mass storage capacity and scalability ofthe high quality storage and broadcasting sub-system, its performance balance design hasbeen done and its reliability model is built based on the theory. Its availability cancompletely meet the requirement of TV Station. The design mothed and the reliabilitymodel can serve as a guide to the design and performance analysis of the storage andbroadcasting system. The broadcasting quality is one of the most important technology issues in the digitalbroadcasting systems. To realize frame precision when broadcast, an algorithm calledMPPDIO (multi-thread parallel pre-fetch Direct IO) is proposed after the characters of thebroadcasting part in uncompressed digital broadcasting system are analyzed. The size of thesharing buffer between multi-threads is modeled and calculated. Experiment results indicate that the traditional pre-cache sequence algorithm can'tmeet the need of performance, and the MPPDIO algorithm not only can perfectly satisfy theperformance requirements but also can improve the utilization of disk I/O channel andreduce the load of CPU. The MPPDIO algorithm can use in the digital broadcastingsystems on HDTV later. The MPEG2 has the advantage of high efficiency in compression; it is suitable for lotof applications of the television station business. The key techniques of digital broadcastingbased on MPEG2 are discussed in detail. A redundancy playing buffer multi-threadingscheme is put forward, and it realizes the frame precision and smooth switch betweenprograms. The scheme doesn't affect both processing playing frame and the pre-decodeing1This research work was supported by the National Science foundation of china under grant 69973017 and 60273074 IIIon frame. It is smarter and costs lesser compared with the current mothed to realized theframe precision and smooth switch between programs by hardware. Some live program must be monitored and delay played to satisfy the special realdemand in television station. It's necessary to research the delay playback technology. Thecurrunt delay playback systems are implemented by LSI and cost huge. We put ingeniouslyforward a scheme realized by share the compression file in disk buffer, after analyzing andcomparing the performance of four kinds different handling methods. This method canrealize availably the function of the delay playback, has no bottleneck in delay timerestriction, and costs least. The digital broadcasting systems demand the real time conversion of file format whenbroadcasting programs. The past conversion of file format is implemented by hardware orsoftware tool, which can't meet the requirment of the system. A kind of real timeconversion method fulfilled by the multithread pipeline scheme algorithm is proposed.According to format characteristics of VOB file in the DVD, each link in conversion thefile format—demultiplex, code and multiplex, is imp...