The Advanced Television Enhancement Forum (ATVEF) is an alliance of leaders in the broadcast and cable industry, the consumer electronics industry, and the computer industry that developed the ATVEF enhanced content specification. The ATVEF specification delivers Web content to television viewers using current Internet technologies over both analog and digital television ( DTV ) systems. ATVEF uses existing terrestrial, cable, satellite, and Internet networks to deliver Web content. ATVEF content is broadcast over one-way or two-way television systems. Supported files include Hypertext Markup Language ( HTML ), Virtual Reality Modeling Language ( VRML ), Java , and private data files. Consumers can receive Web content using a personal computer, cable or satellite set-top box , or WebTV device.
The ATVEF specification consists of three parts: the announcement, trigger, and content:
- The announcement notifies the television viewer of any current Web content available and expires after a set time period. The announcement also includes information that helps the set-top box to decide whether to accept the Web content or to determine whether the Web content is designed to automatically begin without authorization.
- The trigger contains the URL that points to the Web content.
- The content delivered is a collection of Web pages that is displayed along with the television program. It can include text, pictures, and audio files. If the television system is a two-way system, the viewer can browse Web pages and even purchase advertised items using his television.
The ATVEF specification also defines a degree of forward error correction. The data to be transmitted is processed through an algorithm that adds extra bits for error correction. If the Web content is damaged during transmission, the extra bits are used to correct the damage. It also allows the data to be reconstructed if received out of order. The forward error correction defined by the ATVEF specification also allows a viewer to receive Web content even if the viewer has tuned into the middle of a broadcast.