What is MHEG-5?
MHEG is a complete standard for interactive TV and was developed by the ISO Multimedia and Hypermedia information coding Expert Group (MHEG) and the Digital Audio Video Council (DAVIC) from 1995. It is standardised in ISO/IEC 13522-5 “Coding of Multimedia and Hypermedia Information”.
MHEG-5 was developed to support the user interface for DAVIC interactive services and video on demand. It was adopted by the UK Digital TV Group (DTG) in 1997 and deployed on the OnDigital, later Freeview digital terrestrial platform in the UK with a UK Profile covering video, text, graphics and the DSM-CC broadcast carousel system.
MHEG-5 has its own simple object orientated programming language which enables:
- control over the presentation of content made up from audio, video, text and still graphics objects
- user interaction with the application
- support of real time video and audio presentation
The UK Profile defines the complete environment from applications, playout, signalling and the receiver API or middleware. A comprehensive conformance test suite is available from DTG Testing in the UK.
The UK Profile has now evolved to version 1.06 and as of the end of 2007, over 27m receivers including MHEG-5 UK Profile middleware had been shipped into the UK market. There is no known IPR associated with MHEG-5, which has kept costs down and enabled manufacturers to include it in all receivers.
Other countries around the world have adapted the UK Freeview model for their own markets and also adopted MHEG-5 middleware with country-specific profiles. The New Zealand profile extends the UK Profile to include extra Maori characters, the Hong Kong Profile supports Traditional Chinese characters. Draft profiles have been also defined for India, Singapore and China.
The UK DTG has recently completed extensions to support HD services that will be used on the Freesat platform in the UK from May 2008. An ‘Interaction Channel’ extension has also been defined to enable IP connectivity in addition to broadcast delivery of applications and content and PVR integration is also in development.
MHEG-5 is promoted internationally by IMPALA - the International MHEG Promotion Alliance. See www.impala.org for more details.