| 摘要 |
PURPOSE: A method and device for expanding a digital video broadcasting - common interface(DVB-CI) function are provided to provide conditional access(CA) features to a set top unit as if the CA module(CAM) is transparent. CONSTITUTION: A host application processes an object of a CA through a private application program interface(API). Each CAM(120) has its own CA API, however, data channel equally remains in any CAM. Such a new mode coexists with two predefined modes, that is, a low level and high level man machine interface(150, MMI). If a set top unit(STU) "understands" a private CA application program interface(API), CA features can be accessed through the private CA API protocol. Otherwise, CA features remain a standard API. By such an expansion, the STU can have a conditional access user interface which fits overall user interface of STU. A producer can design the STU which is optimized to one given CA or a plurality of CA. Accordingly, conditional access features are assigned to the STU as if the CA module is transparent.
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