- Advanced Common Application Platform
The Advanced Common Application Platform (ACAP) is intended to provide television consumers with advanced interactive services and offer content providers, broadcasters, cable and satellite operators, and consumer electronics manufacturers the technical details necessary to develop interoperable services and products. A common standard is thought to be an essential element for the successful rollout of interactive television.
The work, done within the ATSC Specialist Group on ACAP, was led by Craig Smithpeters of Cox Communications. The ACAP specification is expected to be completed and published as an ATSC standard in Q1 2005.
Interactive television
Two worlds that were once barely connected--television and the Internet--are on the verge of being combined into an entirely new service-- namely, iTV. This combination leads to powerful new applications. For example, computers can be turned into traditional TV receivers and digital
set-top box es can host applications such as iTV, e-commerce and customized programming.iTV may include customized news, weather and traffic reports; personalized stock market data; enhanced sports scores and statistics; games; online real-time purchases; and
Video on demand (VOD).There is no shortage of reasons why iTV is viewed with considerable interest around the world. The backdrop for iTV growth comes from both the market strength of the Internet and the technical foundation that supports it. With the rapid adoption of digital video technology in the cable, satellite and terrestrial broadcasting industries, the stage is set for the creation of an iTV segment that introduces to a mass consumer market a whole new range of possibilities.
For example, technologies are available that support interactive features for game shows, sports and other programs, as well as interactive advertising, e-mail and Internet access. Rather than concentrating just on Web services, the goal is to deliver a better television experience.
The role of ACAP
In essence, ACAP makes it appear to interactive programming content that it is running on a so-called "common receiver." This common receiver contains a well-defined architecture, execution model, syntax and semantics.
As a
middleware specification for interactive applications, ACAP gives content and application authors assurance that their programs and data will be received and run uniformly on all brands and models of receivers.Trial implementations have already been done in
South Korea by a consortium of organizations. In addition, an extensive ACAP demonstration was held at NAB2004.An ACAP application is a collection of information processed by an application environment to interact with an end-user or otherwise alter the stateof- the-application environment. ACAP applications are classified into two categories, depending on whether the initial application content processed is of a procedural or a declarative nature.
These categories of applications are referred to as procedural (ACAP-J) and declarative (ACAP-X), respectively. An example of an ACAP-J application is a Java TV
Xlet composed of compiled Java byte codes in conjunction with other multimedia content such as graphics, video and audio. An example of an ACAP-X application is a multimedia document composed ofXHTML markup, style rules, scripts and embedded graphics, video and audio.An ACAP application need not be purely procedural or declarative. In particular, an ACAP-J application may reference declarative content, such as graphics, or may construct and cause the presentation of markup content.
Similarly, ACAP-X applications may use script content, which is procedural in nature. Furthermore, an ACAP-X application may reference an embedded Java TV Xlet.
The architecture and facilities of ACAP are intended to apply to broadcast systems and receivers for terrestrial broadcast and cable TV systems.
In addition, the same architecture and facilities may be applied to other transport systems, such as satellite. ACAP is primarily based on the GEM (Globally Executable Multimedia) home platform specification developed by the
DVB consortium and DASE, developed by the ATSC.External links
* [http://www.acap.tv/ ACAP web-site]
* [http://www.atsc.org/standards/a101.html ATSC Standard A/101]
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