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1、湖南大学 硕士学位论文 数字电视条件接收系统适配层的研究与实现 姓名：郑思娴 申请学位级别：硕士 专业：软件工程 指导教师：程京;王如龙 20051226 工程硕士学位论文 I 摘 要 数字电视接收系统是指能够接收数字电视广播信号并播放的系统。它主要 包括 MEPG2 解调模块、数字视音频编码器和条件接收模块等。条件接收模块是 由条件接收系统开发公司研制开发，再移植到数字电视接收系统中。地方广电局 可以自己选择条件接收系统进行节目加密。所以开发数字电视接收系统，需要针 对地区移植不同的条件接收系统，这样移植条件接收系统的开发周期对于整个系 统的开发周期起到决定性作用。本课题研究了一种新的移植条
2、件接收系统的方法 即在移植时添加一个新的软件适配层，主要的工作包括： 分析条件接收系统的工作原理和过程；通过移植几种不同的条件接收系统 到数字电视接收系统中，分析移植过程需要编写的代码；结合条件接收系统的工 作原理和过程，针对以往移植条件接收系统只能使一个条件接收系统正常工作的 移植方法。提出了一个新的 CA 软件适配层；并根据条件接收系统的功能设计了 七个适配模块，对每个模块需要实现的功能进行了分析。 研究实现了读写智能卡的适配，在适配层中，实现了对协议的兼容和对协 议类型的判断。适配层通过对协议参数和读写命令进行判断，使得几种不同的智 能卡都能通过适配层与数字电视接收系统的其他模块进行通讯
3、。 研究实现了设置解扰器的适配方法，在适配层中，解决了加扰层不同的问 题。通过适配层对加扰层进行判断并统一数据接口，使不同的条件接收系统都能 成功提取解扰字对解扰器进行设置。 研究实现了适配层的跟踪监测系统，能适配不同的条件接收系统。这个模 块的实现是在检测系统中内部定义跟踪函数，然后在移植的条件接收系统中调用 这些跟踪函数，这样就避免了在跟踪检测过程中条件接收系统因为工作方法或参 数名称类型不同而带来的差异。 关键字：条件接收；数字电视接收系统；适配层；移植 数字电视条件接收系统适配层的研究与实现 II Abstract The digital television receiving sy
4、stem refers the system which can receive and broadcast the digital television signal. It includes the MEPG2 demodulation module, the numeral regards the audio frequency coder and the conditional access module and so on. The conditional access system modules are developed specially then transplants t
5、o the digital television receiving system. Different district will choose the conditional access system to carry on the program encryption, to develop a digital television receiving system, transplantation of different conditional access systems are needed for the different district. Therefore, the
6、transplant conditional access system development cycle plays the decisive role to the overall system development cycle, this article studies on a new method of transplant access system to add a new software adapter level during the process of transplant, the main work includes: After analyzed the pr
7、inciple of work and process of conditional accessing system, transplants the various conditional accessing system to the digital television receiving system, analyzed the compiled code required for the process of transplant, combine the principle of work and process of conditional accessing system,
8、be aimed at transplanting conditional accessing system can only allow single conditional accessing system work normally. Arrange and produce a new software adapter, and design seven difference modules according to the function of conditional accessing system, according to the function need to achiev
9、e for each module, process a concrete analysis. This research realized the method of adapter of read-write smart card. In adapter layer, it totally matched the protocol and also can determine the type of protocols. In the read-write adapter layer, the adapter layer can determine the parameters of pr
10、otocol and read and write command. It enables the communication between the smart card and the other modules of digital television receiving system through the adapter layer. This research realized the method of adapter of setting descrambler, compile an adapter modules to solve the problem of diffe
11、rent method of scrambler. Determine scrambler and unify data interface through the adapter layer, to enable different type of conditional access system to set the descrambler by retrieving the descrambler code. This research realized the track monitor system of CA glue, could suitably match all diff
12、erent conditions receiving system, the realization of this module used the interior of examination system to define the track, again add to the transplant condition receiving system, this avoided the problem on difficulty of tracking due to dissimilar parameter name or the mode of working of conditi
13、onal accessing system. 工程硕士学位论文 III Key Word: conditional access; Digital television receiving system; Adaptation Layer; Transplant; 数字电视条件接收系统适配层的研究与实现 IV 插图索引 图 2.1 TS 流解码过程11 图 2.2 TS 流结构11 图 2.3 TS 包的结构12 图 3.1 条件接收逻辑结构17 图 3.2 同密模式工作原理20 图 3.3 多密模式工作原理20 图 3.4 通用接口模型21 图 3.5 解扰模块结构图23 图 4.1(a)
14、条件接收系统与软硬件的关系25 图 4.1(b) 机顶盒适配层软件结构图27 图 4.2 移植工作示意图28 图 4.3 模块之间关系图31 图 4.4 CA_Player 程序原理图32 图 4.5 CA_Player 逻辑流程图33 图 4.6 CA_Demux 程序原理图33 图 4.7 CA_Demux 逻辑流程图34 图 4.8 CA_Irw 程序原理图34 图 4.9 CA_Irw 程序逻辑流程图35 图 4.10 CA_Flash 程序原理图35 图 4.11 CA_Flash 程序逻辑流程图36 图 4.12 CA_Dsc 程序原理图36 图 4.13 CA_Dsc 程序逻辑流程图36 图 4.14 CA_Osd 程序原理图37 图 4.15 CA_Osd 程序逻辑流程图37 图 4.16 CA_Os 程序原理图
