There can be little argument that interactive TV has had a difficult birth across much of the television world due to technical, cost and marketing problems. But there can be equally little argument that in an increasingly competitive digital TV landscape, interactive TV — from the essential provision of an electronic program guide to more sophisticated applications — is now being recognized as a fundamental part of viewer expectation. The UK market is a prime example of this, though it is hardly alone. Interactive TV has come full circle with cost-effective technology, proven content models, market experience and knowledge all now available.
Interactive TV systems require software components at both the transmission (playout or headend) and reception points (set-top box or integrated digital receiver). MHEG is an open standard middleware — or API — designed specifically for digital interactive TV services. Originally developed and standardized by the ISO in the mid-1990s as part of the Digital Audio Visual Council (DAVIC) standardization effort to support interactivity and navigation for VOD services, MHEG is a public standard with no known essential intellectual property rights or associated license fees. MHEG-5 is now a mature technology and is deployed in the UK in more than 13 million receivers.
With the latest standard — UK Profile 1.06 — a strong conformance test suite has been developed by the Digital Television Group, ensuring interoperability for receiver manufacturers, broadcasters and content creators. The UK Profile, and its ETSI equivalent, provides a baseline specification that is being extended for other MHEG deployments worldwide. One example is FreeView in New Zealand, where additional characters are required. Further extensions to the profile are already in development, for example to incorporate different character sets for Chinese and other Asian markets.
Before examining the way that MHEG works, it is worth looking briefly at its use in the UK's free-to-air digital service Freeview (not to be confused with New Zealand's FreeView). Freeview and its open standards-based approach offers core interactive services that viewers — yes, viewers, using the time-honored lean-back approach to the television — take advantage of on a regular basis. It uses MHEG-5 to provide interactive advertising, digital teletext and multiscreen video selection, as well as other red button enhanced TV services, including home shopping and games.
The result of this standards-based approach is threefold. Firstly, viewers, perhaps without even truly realizing it, have built interactivity into their daily TV usage patterns. More than 40 percent of viewers use the interactive component of some programs, particularly sports. Secondly, by using a widely supported (and hence low-cost) open standard, market forces have led to a vibrant Freeview consumer model for both set-top boxes and receivers integrated into TV sets. Boxes can now be bought for as little as E40. Lastly, broadcasters — the BBC is a prime example — can be confident of near 100 percent audience reach for their value-added interactive services. More than 13 million receivers using MHEG-5 have been sold, which is a significant percentage of the television viewing population.
Alternative strategies that encourage the deployment of higher cost interactive TV receivers alongside low-function zapper boxes inhibit the development of widespread interactive TV services, as typically only a small proportion of the audience is interactive-capable. Other, more complex standards for digital interactive TV also come burdened with higher costs through intellectual property rights licenses.
New Zealand's digital platform
Recently, the FreeView consortium in New Zealand — the free-to-air digital television platform using satellite and terrestrial distribution — announced its decision to deploy MHEG-5 as its interactive middleware. This follows an extensive proof-of-concept trial hosted by broadcaster TVNZ using sample MHEG-5 applications and set-top boxes.
The MHEG-5 system is simple, and its client software can be implemented in a wide range of low-cost digital TV receivers. The client software consists of an MHEG engine (or virtual machine) that interprets MHEG applications and presents information delivered to it via a carousel file system or a return channel. MHEG enables interaction between the user and the application through the remote control and in some implementations allows the application to exchange information with a remote server via an IP connection.
The MHEG programming language broadly comprises objects for presentation, links that respond to events and resident programs. Presentation objects include video, audio, lists, text and graphics. Events respond to input from the remote control, a timer, a stream event message in the broadcast or the result of a logical condition in the application. Resident programs are native functions, defined in the profile, that extend the basic MHEG to provide specific tools to manipulate data.
The broadcast MHEG profiles have a simple life cycle, allowing only one application to run at a time. One MHEG application can launch others, but after doing so, the original is terminated. In a broadcast system, an auto-launch application may be started when a service is selected with which it is associated. The auto-launch can then start other applications and select to tune to other services. Information can be passed between applications by making use of persistent store in the receiver.
MHEG applications
An application is normally loaded from the digital storage media command and control (DSM-CC) object carousel or optionally from the return channel or from a DVB Common Interface (DVB-CI) module. Data loaded from the carousel can be updated rapidly on-screen as the content of a data object changes. Information is presented either as included content, where the text or graphic is embedded in the application, or as referenced content, which is acquired from the carousel as required. A strategy of building applications with predominantly referenced content enables them to remain stable, with changing content and graphics and even detailed layout, over an extended period.
MHEG can be used, for example, to build an EPG application that efficiently delivers data in the DSM-CC object carousel and presents it using MHEG. These systems allow the user to tune to a chosen channel from the EPG, and this gives the platform operator the opportunity to provide a consistent EPG rather than rely on a receiver manufacturer's implementations.
Applications can present and navigate around such textual information as news, weather, financial data and sports results. Navigation can be through list and select processes, and applications can also replicate the page number navigation of teletext. Advertising within such applications can be graphically rich and related to individual pages of information.
This type of information can be extended, where a return channel is implemented, to participation, voting, betting and shopping functions. This allows the user to buy from a catalog of items or bet on the outcome of an event on the screen. Home shopping can also be supported using call center response and purchasing or via SMS messages. These will probably need to be supported in any case, because not all users will use a return channel system. Most information publishing applications are presented as distinct services that are available 24 hours a day.
The MHEG platform can support a range of simple games, including those that involve the viewer in active use of the remote control — for example, the famous interactive game Tetris, interactive TV darts or Spot the Ball. Interactive quiz games can be built with questions that change on a regular basis. Many games popular on mobile phones may be implemented.
The same types of applications can be used to deliver information to supplement the content of a particular linear program or advertisement. For example, text and pictures providing background information can accompany a documentary series or music concert. Games can be created that play along with the running video. Stream events can be used to synchronize actions in the application with the A/V stream where required.
MHEG, when running, controls scaling and presentation of video and presentation of audio. This provides the means to tune to other services and to switch between running video streams in the same multiplex. This allows a broadcaster to show more than one view of an event — for example, various matches at a tennis tournament, different players in a golf tournament or alternate views of a football match. Control of video and audio selection is achieved using the MHEG application associated with the service, not by the receiver navigator.
Current implementations
Most current implementations of MHEG receivers conform to the UK Profile 1 specification. This has been updated to V 1.06, now being shipped in the UK market. This specification forms the core part of the ETSI-MHEG profile. Specifications are under development and standardization for low-cost return channel capability using IP communications. It is possible simply to include support for standard VOD control — one of the original purposes of MHEG — in return channel capable profiles.
MHEG is both cost-effective and technologically efficient. It is highly focused on the task at hand — that is, being a system for TV interactivity. It carries no baggage, and it occupies a small amount of space in the receiver to handle applications that are specifically designed to enhance the TV experience. It benefits from a lightweight user interface, and it is powerful enough to provide sophisticated interactive services. Including an MHEG-5 1.06 engine is an incidental cost for receiver manufacturers with its the modest memory and CPU requirements.
International MHEG Promotion Alliance (IMPALA) has been set up to promote MHEG on a global basis and showcase its success to those looking at rolling out interactive services, as well as to those who have not yet considered it. This has become a market-proven option and opportunity. There has been rapidly growing interest for some time, and the new commitment to roll out in New Zealand should be the first of many.
David Cutts is managing director of Strategy & Technology and is a founding member of IMPALA, which is a newly formed not-for-profit organization that promotes the use of the MHEG-5 international standard in digital TV worldwide.
