Enhanced TV offers content and data enhancements to traditional broadcast programming. In the standard scenario, a small visual icon appears during the programming that alerts the viewer to the fact that interactive content and information is available. When the viewer selects to see the enhanced experience, the interactive areas will either overlay the video or surround a smaller video feed.
In a news program, for example, the viewer could click the alert icon to access a news story in more depth. A popular show or movie could be surrounded by a chat application to allow geographically separate viewers to talk about what they're watching or just make new friends. A game show can allow viewers to play along in real time with the television show and even compete with all the other interactive players.
Given current viewing habits, it seems that news, sports, game shows, financial and educational programming, how to programming such as cooking shows, infomercials, music videos, and advertising offer the most robust areas to focus on creating enhanced television.
Flash is beginning to be integrated into the synchronization tools that create these enhanced television experiences. The way enhanced television works is that triggers are created and sent over a portion of the broadcast signal with the television show. The trigger requests that the set top box load specific web-based content load and combine it with the television picture.
There are two types of triggers, both based on standards created by the ATVEF (Advanced Television Enhancement Forum, www.atvef.com). The ATVEF is a consortium of companies creating protocols for enhanced programming and its delivery to television.
Type A triggers deliver the information about the web URL over the broadcast signal and then require a modem connection to download the web-based content. Information delivery is in line 21 of the vertical blanking interval (VBI), the same line used for closed-captioning.
Type B triggers deliver both the URL and the content over the broadcast signal. Type B triggers can use lines 10 through 20 of the VBI, but can only use a certain number at a time. Broadcasts might be using these lines for other reasons as well.
Both types of triggers have advantages and disadvantages. Type A triggers deliver content more slowly, but never run into broadcast signal problems. Type B triggers can be faster, but require more of the broadcast signal to be free. Because interactive content creators don't always have control over this situation this can cause problems.
The exact technical nature of the ATVEF triggers is described in the documentation on its web site, but the main parts of the trigger defines the content that is requested, where it is requested from, and if there's an expiration date on the content.
Liberate operates a free partner program to gain access to its suite of tools, while both Microsoft and OpenTV offer a fee-based partner program. Liberate's program provides partner materials such as a television emulator that can play back enhanced TV programming on a PC if a TV card has been installed on the computer.
Over the next year, the enhanced TV market will begin to consolidate and provide opportunities in the United States to create programming. Until then, it's best to keep an eye on what's happening in the field and be ready for when opportunity arrives.