ABSTRACT
Contents 20.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602 20.2 Interactive Service Design Scenario. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 606 20.3 DVB Portable Content Format Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608
20.3.1 Introduction to Content Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608 20.3.2 Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610 20.3.3 Structuring a Service Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610 20.3.4 Managing Differences between Platforms . . . . . . . . . . . . . . . . . . . . . . 612 20.3.5 Media Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 612 20.3.6 Return Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 613
20.3.7 Comparison with Other Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . 613 20.4 PCF Transcoding Use Case: Generating Web-Based Contents . . . . . . . . . 614
20.4.1 PCF Validation and Parser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615 20.4.2 Translating the Layout and Its Components . . . . . . . . . . . . . . . . . . . 615 20.4.3 User Interaction and Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616 20.4.4 Media Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 617 20.4.5 Client-Server Communication: AJAX . . . . . . . . . . . . . . . . . . . . . . . . . . 617
20.5 Production Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618 20.6 Use Case for Interactive Services: Learning Environments . . . . . . . . . . . . . . 621 20.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623 20.8 Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624
20.1 Introduction Interactive television represents the adaptation of this communication media to an environment in which viewers demand greater significance and new services that suit their preferences. These interactive services are implemented by means of interactive applications, which can be defined as those additional programs related to television content which are accessible and can run in an interactive TV decoder. The user decides whether or not to view the interactive applications through a simple action with the remote control device. In order to inform the user concerning how to access interactive applications, operators and television channelsmust provide a smallmenu that tells the user that they can see an application or a group of interactive applications. The number of different devices that can access TV services and the interactive content is growing rapidly due to the technological advances in consumer devices and communication networks. A clear example of this are smartphones, which can be considered as handheld computers with powerful processors, abundant memory, and larger screens than contemporary feature phones, that is, low-endmobile phones that have less computing ability than a smartphone, but more capability than the largely obsolete portable cellular telephones made from 1983 to 1999, known as “dumb phones.” The new wave of devices also rely on and take advantage of the mobile broadband networks (i.e., third-generation mobile networks) that provide the required speed and support for Internet browsing, enabling a new generation of interactive services for mobile devices. Smartphones, however, are not the only newly available consumer devices capable of accessing iTV services. Based largely on the success of Apple’s iPad, the market seems to be in a race to introduce new tablet personal computers (tablet PCs) equipped with a touch screen as a primary input device, wireless adapters for Internet browsing, and screens that are larger than that of smartphones. That said, the traditional home environment for watching TV is also evolving to meet the needs of the modern consumer with Internet access, the production of user-generated content, the participation in social networks, and
the provision of on-demand content. The implementation of these features over the broadcast channels and their efficient combination with IP services is an ongoing challenge that is faced in the interactivity provided by the TV consumer platform, which is based on interactive applications. These new devices that integrate Internet into the traditional TV sets and set-top boxes (STBs), also known as connected TVs (e.g., Google TV), most often have a much higher focus on online interactive media, over-the-top content, and on-demand streaming media that in previous generations of TV sets and STBs were simply not available. This scenario of new platforms and converged networks suggests that interactive contents are becoming more and more important in the leisure activity that is watching TV and suggests the need for an analysis of interactive content as well as of its production in a platform-independent way.
