scope:

Introduction

The present document describes a complete system that provides for enhanced interactive TV in the context of a television service that uses the standards set out in the published ETSI specifications for digital TV. Applications for the technology include programme guides, information services, games and enhanced TV services with synchronized interactions and multiple content streams. The Profile identifies the minimum functionality that the receiver will need to support.

The present document contains a number of clarifications related to streaming content and stream event handling and various other changes to increase interoperability of implementations of the specification.

Localizing the present document

Approach to creating a local implementation

Unless otherwise stated, the functionality in the present document is mandatory.

In addition, there is functionality which should be considered in a local implementation of the Profile. This information should be put into a localized profile of the ETSI-MHEG Profile. The following issues are addressed when determining what information is necessary in a localized profile:

• which extensions are mandatory or optional;

• allocation of codes;

• handling duplicate services. 

Extensions

The present document also describes a number of "extensions". An "extension" is a collection of functionality that, if provided, is implemented as a whole. In some cases it may be necessary to implement one or more extensions in order to satisfy mandatory functionality. In other cases implementation of a extension may be optional. For a particular implementation, a localized profile specifies exactly which extensions are mandatory or optional.

• Signalling extension:

- Functionality for identifying and booting an application is provided by the PMT and ServiceGateway extension (see clause 9.3).

• Service Information extension:

- Functionality for retrieving DVB Service Information (SI) is provided by the SI extension (see clause 11.14). A localized profile states whether this extension is mandatory or optional.

• HDGraphicsPlaneExtension (see clause 12.11.1):

- This extends the MHEG-5 engine to allow support for an HD graphics plane.

• HDVideoExtension (see clause 12.11):

- This extends the MHEG-5 engine to allow support for HD video and audio coding and presentation.

• InteractionChannelExtension (see clause 15.1.2 and table 11.14);

- This extends the MHEG-5 engine to allow support for static content retrieval over an always-on IP connection.

• ICStreamingExtension (see clause 11.5.4 and table 11.15):

- This extends the MHEG-5 engine to allow support for static and streaming content retrieval over an always-on IP connection. Receivers that implement ICStreamingExtension also implements InteractionChannelExtension.

• LifecycleExtension (see clause 8.1.7):

- This extends the MHEG-5 engine to allow MHEG-5 applications to continue running across service tunes.

• NativeApplicationExtension (see clause 17.2.2 and table 11.16):

- This extends the MHEG-5 engine to allow the co-existence of MHEG-5 applications and broadcast-triggered native applications.

• DownloadableFontExtension (see clause 13.3.1):

- This extends the MHEG-5 engine to allow support for a range of typefaces, styles and sizes for text presentation.

• PVRExtension (see clause 11.15):

- This extends the MHEG-5 engine to allow support for booking events on a PVR from an application.

• InputMaskExtension (see clause 11.14.2):

- This extends the MHEG-5 engine to allow fine grained control of user input.

• File System Acceleration Extension (see clause 11.16):

- This extends the MHEG-5 engine to allow receivers to persistently store a preselected part of a File System in order to improve the speed of subsequent file access.

NOTE: Extensions are not partially implemented

Allocation of codes

The present document provides for an "application_type_code" (see clause 9.3.2.1) and a "GetEngineSupport string" (see clause 11.4.1) for determining what level of conformance a receiver has with the Profile (or with a localized profile of this Profile). It may be necessary for a localized profile to state additional codes beyond those already provided by the present document if:

• the localized profile provides extra functionality beyond this Profile;

• receivers exist in a local network that are not yet fully conformant with this Profile and the localized profile of it.

Duplicate services

Occasionally a receiver may have to select from 2 or more duplicate services (see clause 16.3.3.3). The present document provides functionality that can be used to handle selecting duplicate services. If a local implementation wishes to use a different mechanism for handling duplicate services this is specified in the localized profile for that implementation.