1.1 Interactivity

The interactivity of TV is orthogonal to the implementation of the wide High Definition (HD) format; a TV can be interactive yet Standard Definition (SD), and it can be noninteractive yet HD. Interactive TV programs are those with which the viewer can interact. Interactivity may take multiple forms, utilize some input device, and occur against a local disk or through a return channel that is similar to an Internet connection. Typically, interactivity is enabled by, and takes the form of, menu and link selections (see Figure 1.1). For advertisements, interactivity may mean browsing information about products (or services) and possibly purchasing online (i.e., performing financial transactions). For Electronic Program Guides (EPG) interactivity may mean searching the guide. For Video On Demand (VOD), interactivity may mean selecting a video and controlling its playback. For game shows, interactivity may mean playing the game and possibly stimulating competitions among viewers in addition to competitions against contestants. For news programming, interactivity may mean browsing a news site in a fashion similar to modern news Web sites. For sports TV programs, aside from interactive commercials, interactivity may mean the ability to obtain statistics, and replay selected portions from several angles. For trading, gambling, and auctioning, interactivity may mean placing bets or bids. For travel reservation applications, interactivity may constitute making reservations online.

Figure 1.1. An example iTV 'splash' screen courtesy of Microsoft.

In principle, digital TV and iTV receivers are similar to traditional analog (e.g., NTSC, PAL) receivers in that they receive video signal and viewer selection through Remote Control (RC), and render the video on a display. Digital TV (DTV) receivers differ from traditional receivers in that the video and audio are delivered via MPEG transports. Interactive TV receivers further enhance DTV receivers with the capability to process data 'track' delivered simultaneously with the video and audio, and which contains applications (see Chapter 2 for examples). This data can be delivered via MPEG or (Internet Protocol) IP transports, and can be uploaded onto a wide range of hand-held accessories (see Figure 1.2). However, the major technical departure for iTV receivers beyond noninteractive digital and analog receivers is the need for a middleware software component as well as a powerful operating system. The complexities introduced by these additional software layers are mind boggling. This book is an introductory reference to these issues, technologies, and the standards addressing them.

Figure 1.2. The iTV framework and supporting technologies.