Multimedia Hypertext Experts Group is standardised open source software that defines the authoring and presentation of interactive applications for digital television.
Broadcasters use MHEG to develop applications that enrich the viewing experience. MHEG compliant digital television receivers allow the viewer to access and interact with data services, consumer services, games and interactive advertisements. MHEG applications are also used to provide access to additional video content associated with a broadcast event via an application.
Broadcasters play out the application components via a data carousel injected into the broadcast stream. The MHEG Engine in the compliant digital television receiver then decodes and presents the MHEG data stream to the viewer in the form of the interactive application.
MHEG is deployed in the UK on both digital terrestrial and digital satellite platforms – variable transmission bandwidth allocated to the MHEG applications makes efficient use of the available broadcast capacity. Applications can make up a dedicated broadcast service or take the form of a small, discrete application – a trigger – used to prompt the viewer to a larger MHEG application.
As well as broadcasters controlling the display of an MHEG application, an application can be launched via the television remote control text button. Viewers navigate applications with key presses on a standard television remote control, including Left, Right, Up, Down and alphanumeric buttons. The experience is improved further by the use of the Red, Green, Yellow and Blue remote buttons.
In addition to interactive applications, MHEG is used in some countries to generate the digital television platform Electronic Programme Guide (EPG).
The MHEG specification defines the classes and features required to correctly decode and present interactive TV applications, including content formats and APIs that must be implemented for all receivers. It is published as an International ETSI specification, which is further profiled in the D-Book.
Catch-up VoD services traditionally available through an internet connected PC can be written in MHEG so viewers can access broadcaster archive content using their digital television receiver and standard remote control. The DTG’s D-Book 6.2.1 specification introduced features enabling an MHEG application to use the IP connection of the digital television receiver. The MHEG system presents a similar user experience to that found online, so viewers never have to miss an episode of their favourite TV programme.
Web-based presentation technologies like HTML and Adobe Flash can also be optimised in digital television receivers. An MHEG trigger application and IP connection enable the broadcaster to offer the user richer applications and services. These applications and services have to be developed for remote control user interaction, instead of keyboard and mouse. D-Book 8 defines the rules for the coexistence of different presentation technologies in the Connected TV ecosystem.
The DTG hosts an MHEG working group to manage the evolution of the UK DTT MHEG profile. DTG Working Groups are open to all Full and New Entrant Members. For details contact [email protected]
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