Advanced Television Enhancement Forum initiative for web-based interactive television.

The ATVEF consortium included CableLabs, CNN, DirecTV, Discovery, Disney, Intel, Microsoft, NBC, PBS, Sony, Tribune and Warner Bros. The work of the consortium formed the basis for a SMPTE standard.

ATVEF essentially provides a mechanism to deliver triggers in the video stream to activate web-based content. This allows enhanced programmes to deliver synchronous material contextually related to specific points in the programme.

The method covers the transmission of triggers in an analogue signal or the delivery of data and triggers in a digital signal.

ATVEF Transport A or ATVEF-A provides for the transmission of triggers in line 21 of the vertical blanking interval or VBI of a television signal in a similar manner to closed caption subtitles. Consequently this method is compatible with analogue broadcasts and the video can be recorded on conventional broadcast equipment.

Content is delivered on demand over the internet. The standard assumes that content is produced in basic HTML and the level of browser support is broadly equivalent to HTML 4.0 and JavaScript 1.1 with support for CSS1 stylesheets, png and jpeg images and audio. The video channel may also be displayed within the HTML page.

This system has been used with WebTV, Ultimate TV and AOL TV services.

ATVEF Transport B or ATVEF-B delivers the enhancement data together with the audio and video within an ATSC digital broadcast signal.

In this case content is sent prior to a trigger so that it is cached in the receiver ready for use. The content may be static or synchronous with the programme.

The original ATVEF specification was subsequently defined in SMPTE standards for what is known as Declarative Data Essence or DDE.

A similar approach was adopted in the provision for the ATSC DTV Application Software Environment or DASE.