Platform Profiles

MHP isn't just a single, monolithic standard where there is absolutely no variation between compliant receivers. Some parts of the standard are optional, as we'll see later, but most importantly the MHP specification defines three profiles that applications can use to define what features they need. These profiles allow application developers and broadcasters to be sure that receivers will support a common set of functionality, while allowing receiver manufacturers to produce different prueducts at different price points. Profiles are not always an ideal solution, but when chosen well they offer a good compromise between flexibility and interoperability.

The three profiles in MHP are:

  • the Enhanced Broadcast Profile
  • the Interactive Broadcast Profile
  • the Internet Access Profile (added in MHP 1.1)

Of these three profiles, the Enhanced Broadcast Profile is the most basic, and provides no mandatory support for an IP connection over a return channel. It also imposes some restrictions on the type of JPEG images that may be used.

The Interactive Broadcast Profile adds support for IP networking to the Enhanced Broadcast Profile, although support for DSM-CC over an IP connection and HTTP 1.1 is still only optional. It also adds mandatory support for communicating over the return channel and recommended support for IP multicast. Finally, it removes the restrictions placed on JPEG images in the Enhanced Broadcast Profile.

Finally, we have the Internet Access Profile that is added in MHP 1.1. This adds mandatory support for Web, email and Usenet news client applications and an API to access these clients, as well as making the support for IP multicast mandatory.

Each of these three profiles may have multiple versions, indicated by a number after the profile name. For instance, Enhanced Broadcast Profile 1 is version 1 of the Enhanced Broadcast Profile (defined by MHP 1.0.x - MHP 1.1.x defines Enhanced Broadcast Profile 2). Each version must be a proper superset of the previous version, so that any functionality present in the current version must be present in the next version. This is further divided by the actual version number, which corresponds to the version number of the MHP specification.

More detailed profile information is as as follows:

MHP profiles and the functionality they include.
  Enhanced Broadcast Interactive Broadcast Internet Access
Core APIs Mantadory
Basic application lifecycle support ( package) Mantadory
Application listing & launching API Mantadory
Inter-application communication API Mantadory
HAVi Graphics API Mantadory
Java Media Framework and extensions Mantadory
Service selection API Mantadory
Tuning API Mantadory
Basic MPEG concepts (org.davic.mpeg) Mantadory
Resource notification API Mandatory
MPEG section filter API Mantadory
DVB service information API Mantadory
JavaTV service information API Mantadory
Conditional access API Mantadory
Persistent storage API Mantadory
Non-CA smart card API Mandatory (note that the smart card API in MHP 1.1.2 is different from that in other versions of MHP)
Security classes and extra permissions classes Mantadory
Return channel connection management API Mandatory in MHP 1.1.2,

not required otherwise
DSM-CC over the broadcast channel Mandatory
IP over the return channel Optional Mantadory
DSM-CC over the return channel   Optional
Filesystem over the return channel (non-DSM-CC)   Mandatory (MHP 1.1.x only)
IP multicast support (using any encapsulation mechanism) Optional Recommended Mandatory (version 1.1.x only)
HTTP 1.1 support

Optional Mantadory (version 1.1.x only)
Support for stored services Mandatory (MHP 1.1.x only)
Plugin support Mandatory (MHP 1.1.x only)
XML parsing API Mandatory (MHP 1.1.2 only)
Cryptographic API Mandatory (MHP 1.1.2 only)
DVB-HTML support   Optional (MHP 1.1.x only)

DVB-HTML applications typically have higher platform requirements than DVB-J applications, and so they typically won't be usable on platforms that don't meet the Internet Access Profile. Most platforms that have all the needed support will likely have a full-blown web browser, and so these platforms probably comply with the Internet Access Profile.

Profiles and application signalling

The AIT will contain an Application Descriptor that contains information about which profile (and which version of the profile) the application needs to run. This allows a receiver to know in advance whether an application will run, and not attempt to start applications that don't match the profile. When a reciver gets a new AIT, as part of processing the AIT (detailed in the section on the application lifecycle) it will check the profile and version number to check whether that application is applicable to that receiver. If not, it will ignore that AIT entry.

Applications can find out which profile a receiver supports using system properties. MHP defines a number fo new system proprties for identifying the profiles (and profile versions) supported by a receiver, as well as for discovering which optional features are supported by a given receiver.