Multimedia Home Platform

Multimedia Home Platform (DVB-MHP) is an open middleware system standard designed by the DVB project for interactive digital television. The MHP enables the reception and execution of interactive, Java-based applications on a TV-set. Applications can be delivered over the broadcast channel, together with audio and video streams. These applications can be for example information services, games, interactive voting, e-mail, sms or shopping. For all interactive applications an additional return channel is needed.

Deployment

By mid-2005 DVB-MHP largest deployments are in Italy (DVB-T) and Korea (DVB-S), with trials or small deployments in Germany, Finland, Spain, and Australia. The U.S. cable industry has specified its own middleware system referred as OCAP, which is largely based on MHP. Currently, Belgium's largest cable provider Telenet is rolling out their DVB-MHP system, called DigiBox.

Technology

The MHP specifies an extensive application execution environment for digital interactive TV, independent of the underlying, vendor-specific, hardware and software. This execution environment is based on the use of a Java virtual machine and the definition of generic APIs that provide access to the interactive digital TV terminal's typical resources and facilities. The interoperable MHP applications are running on top of these APIs. A so-called Navigator-application, which is part of the terminal software, allows the user the access to all MHP applications and other DVB services (like TV and radio).

The MHP is just a part of a family of specifications, which all base on the Globally Executable MHP (GEM)-Standard, which was defined to allow the world-wide adoption of MHP.

DVB-HTML

MHP applications come in two flavours. The first type are DVB-HTML applications. These are not very popular, partly because the specification for DVB-HTML was only completed with MHP 1.1, and partly because many broadcasters, box manufacturers and content developers find it too complex and difficult to implement. DVB-HTML applications are a set of HTML pages that are broadcast as part of a service. The spec is based around a modularized version of XHTML 1.1, and also includes CSS 2.0, DOM 2.0, and ECMAScript.

DVB-J

The second, and by far the most popular flavour is DVB-J (DVB-Java) applications. These are written in Java using the MHP API set and consist of a set of class files that are broadcast with a service. DVB-Java applications are known as "Xlets". These are a concept similar to applets for Web pages that has been introduced by Sun in the JavaTV specification. Like applets, the xlet interface allows an external source (the application manager in the case of an MHP receiver) to start and stop an application.

Return channel

The MHP set-top boxes may provide a backchannel for applications that wish to communicate with the outside world, for example a voting or shopping application. Typical upstream backchannels are phone line or broadband Internet connection (ADSL, using a simple ADSL modem included in the set-top box). This is the difference with zapper set-top boxes.

References

Ulrich Reimers: DVB, The Family of International Standards for Digital Video Broadcasting, Second Edition, 2005, ISBN 3-540-43545-X (chapter 14, MHP)

External links

Official MHP website maintained by the DVB Project Office.
MHP tutorials
MHP Knowledge Database

OpenMHP - MHP-Open Source Project
Sun Microsystems' Java TV
iTVBox - MHP Research & Development Laboratory
xleTView - xleTView, MHP-Open Source Emulator at Sourceforge
Interactive-TV-Web - MHP/OCAP Website from Steven Morris

Interactive television | Java platform | Java virtual machine

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