Europe’s TV standards group DVB has designated GEM as its primary middleware technology in place of MHP - after standardisation body ETSI adopted it as a self-contained specification.

GEM - which stands for Globally Executable MHP - was, as its name suggests, a DVB-independent derivative of MHP (Multimedia Home Platform), a Java-based system originally proposed as a common European interactive TV platform.

Now, GEM becomes a standard in its own right, eclipsing MHP.

The original idea behind MHP was that its inclusion of a Java Virtual Machine would enable interoperability of interactive TV applications across different digital TV platforms. But in practice, MHP implementations turned out to be stripped-down, customized affairs that were only nominally independent of the platforms that deployed them.

MHP boxes also generally cost more than ones using interactive technologies such as OpenTV or MHEG, a factor which was exacerbated by an unexpected hike in licensing-fees in March 2006. MHP interactive environments also proved costly to maintain.

Thus, apart from MHP’s success in colonizing the Italian DTT market (the result of a government subsidy being made available for interactive set-top boxes), the middleware was never widely adopted.

GEM has now emerged as the more significant technology: (a) it is incorporated into the high-definition optical disc standard Blu-Ray; (b) it forms the basis for the US Opencable standard (under the brand ‘tru2way’); and (c) it underpins Brazil’s interactive middleware standard Ginga-J.

GEM is also compatible with the US and Japanese digital terrestrial broadcasting standards.

DVB claims that GEM/MHP technology is currently in around 50m devices worldwide, the vast majority of which are likely to be Blu-Ray players, in Farncombe’s view.

However, the trend towards hybrid decoders and connected TVs indicates that such broadcast-specific interactive TV platforms have probably had their day. In the future, interactivity on the TV is likely to use the broadband link and to derive from existing, tried-and-tested Internet technologies, with new standards such as Europe’s HbbTV and the UK’s Canvas pointing the way.