摘要
电视数字化是电视发展史上又一次重大的技术革命。数字电视不但是一个由标准、设备和节目源等多个部分相互支持和匹配的技术系统,而且将对相关行业产生影响并促进其发展。它给观众带来了主动接收的方式;给接收设备提供商带来了发展机遇;给有线电视网络和卫星电视带来了新的业务和机会。而这一切都依赖于一个先决条件:一个灵活、高效功能强大的条件访问系统(CAS)。
本文在全面研究了CAS相关标准和基本原理、CAS复用机制、CAS构成、CAS通用加扰算法的基础上,结合对面向服务的架构(SOA)的研究、实现SOA的相关技术的研究、SOA生命周期的研究、SOA逻辑架构模型的研究和WSIF的研究,实现了一个基于SOA的CAS前端。提出并实现了高效服务流水线加扰,解决了软件加扰的速度瓶颈问题,实现了高效灵活的CAS前端。CAS其它部分代之以运营支撑系统(BOSS)框架,这样可以保证满足数字电视频道和节目管理及其它增值业务的管理和运营需求。由于SOA本身的高灵活性、业务敏捷性和高可靠性,加上高效服务流水线加扰的实现,该CAS前端是一个能够适应复杂环境并且是灵活高效的CAS前端,与目前存在的CAS系统相比,明显具有更高的灵活性和更好的业务敏捷性。
对软件原型测试表明,整个CAS前端包括高效服务流水线加扰能够正常工作,在负载流量超过4M时能稳定工作。没有解扰授权的用户可以收到加扰后的视频流数据,但不能正常收看视频流节目。虽然只是原型测试没有布署到试点前端进行长时间和实际运行测试,也没有进行大规模测试和极限测试,但所表现出来的灵活性、业务敏捷性和很高的加扰速度和加扰稳定性己经超过了目前存在的同类产品。
The digitalization of TV is another great technology innovation in the history of TV development. Digital TV is a technology system involving standards, equipments and program sources, etc. These parts support and adapt to each other, it will affect and promote the development of related industries. Digital TV brings a voluntary manner to the customs, development chances to the receiving device dealers, and new business and opportunity to the CATV and Satellite TV dealers. All of the above depend on one precondition, a flexible CAS with high efficiency and power force.
In this article, the author make the research of the standards, the basic principles, the mechanism of reusability, the structure of CAS, the common scrambling arithmetic. After that, the author research the architecture of SOA, the related technology about the implementation of SOA, the lifecycle of SOA, the model of logical architecture of SOA and WSIF. Then a CAS Head-end based on SOA is implemented. Presented the arithmetic of service-pipeline scrambling ,and implemented it .By useing this method ,the bottle-neck of speed caused by general scrambling system which is implemented as a software is overcome. As for the high flexibility, reliability and the implementation of parallel scrambling service module, the CAS Head-end can adapt complex environment, it is a flexible CAS Head-end with high efficiency.
Indicated from the software prototype test, the entire CAS Head-end, which including the highly effective service-pipeline scrambling, can the work normally. And can word stably when band width is 4M.The users without unscrambling authorition can receive only scrambling vidio stream, which could not get the right programe. Althought it is just a prototype test and without any long term, real time,big scale and extremly tests. But its agility,business celerity,high speed scrambling and scrambling stability has already exceed many other present products.
引文
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