MHEG-5 (Digital Teletext) Information
MHEG-5 is part of the ISO/IEC 13522-5 Multimedia and Hypermedia Experts Group (MHEG) international standard used for "interactive services" in UK digital terrestrial television. These include:
MHEG-5 is a language for describing multimedia presentations as a collection of objects.
MHEG-5 is object orientated
An object hierarchy is defined, with objects inheriting attributes of their base class. To display a presentation, an MHEG-5 Application is started. This must load a Scene before anything can be displayed. Applications and Scenes include lists of Items (other MHEG-5 objects) called Ingredients. Ingredients can belong to the Visible class, meaning that they are displayed on screen or can be non-visible, such as Links, Programs or Variables.
MHEG-5 Events, Actions and Links
Events are things that can make something happen. Actions are things that can happen. Links bind Events to Actions by specifing when this Event happens, perform these Actions.
MHEG-5 defines two different event types:
ElementaryActions perform single operations, such as:
An Action is a list of ElementaryActions.
A Link is an MHEG-5 object that waits for a specific Event to occur, then executes an Action. An example could be a Link that waits for the user to press the red button, and executes an Action to display a menu.
Links implement dynamic behaviour within MHEG-5 Applications.
See a simple "Hello World" MHEG5 script.
View and download a simple MHEG5 Invaders game example.
Download MHEG-5 Textual Notation syntax definitions for TextPad.