With advanced analog cable set-top boxes, early digital satellite boxes and recently with digital set-top boxes, television viewers are getting used to more than just audio-visual (NV) content. Enhanced broadcast includes graphical and data enhancements to the specific NV program, such as additional text, graphics, user choices, teleshopping, etc. Standalone applications such as electronic program guides are becoming a norm. All current deployment of such systems is based on proprietary solutions.
The Internet and the Web in particular was enabled by platform independent content formats such as HTML and Java. The same must happen in order to deliver enhanced content and downloadable applications to digital TV receivers of all kinds including terrestrial receivers, cable set-tops, satellite receivers and computers. A platform independent content format is not enough to provide a rich, well-integrated audio/video/data content to all possible receivers. These devices must have a common set of application programming interfaces (API) in order to make downloadable content and applications truly interoperable. The goal of these AP/s is to provide access to the receiver functions such as tuning and channel changing, receiver resources such as a return channel and the TV screen, as well as system information necessary for channel navigation and program guides. User-specific data such as user preferences and personal data may also be made available to applications via these AP/s.
This paper addresses the current work-in- progress in the ATSC T3/S17 specialist group also known as the DTV Application Software Environment (DASE), specifically the definition of Java AP/s. Classification of downloadable applications is presented together with a set of requirements that must be met in order to enable such interoperable applications. Also a detailed description of all DTV receiver system services that are being abstracted by the Java AP/s is presented. The focus of this paper is on Java-based downloadable applications that are enabled by the presence of a Java interpreter in the form of a Java Virtual Machine (JVM) and a set of Java AP/s providing access to the DTV receiver functionality.