Editing MHEG-5

{{Short description|Set of international standards}}
{{distinguish|MPEG}}

'''MHEG-5''', or [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] 13522–5,<ref>{{cite web |url=http://www.iso.org/iso/catalogue_detail.htm?csnumber=26876 |title=ISO/IEC 13522-5:1997 - Information technology -- Coding of multimedia and hypermedia information -- Part 5: Support for base-level interactive applications |author=ISO |access-date=2010-08-01}}</ref> is part of a set of international standards relating to the presentation of multimedia information, standardised by the [[Multimedia]] and [[Hypermedia]] Experts Group (MHEG). It is most commonly used as a language to describe [[interactive television]] services.

== Characteristics ==
MHEG-5 is a licence-free and public standard for interactive TV middleware that is used both to send and receive interactive TV signals. It allows a wide range of TV-centric interactive services to be deployed. It is used by [[Freeview (UK)|Freeview]] and [[Freesat]] in the UK, [[Freeview (New Zealand)|Freeview]] in New Zealand, [[Television Broadcasts Limited|TVB]] in Hong Kong, [[Freeview (Australia)|Freeview]] in Australia, [[Saorview]] in Ireland and has been specified in South Africa.

Recent{{when|date=November 2017}} work by the DTG in the UK has led to the development of the MHEG-5 Interaction Channel (MHEG-IC), which enables an extension of broadcast interactive services to be delivered via an IP connection. The principles behind the MHEG-IC are to provide a seamless viewer experience of broadcast delivered content augmented with content delivered over IP as an extension of the channel or network. Broadcasters have full editorial control of the user experience. The MHEG-IC gives access to streamed on-demand video content in addition to traditional text and graphics as well as the ability to support secure transactions.

MHEG-5 is an [[object-based]] [[declarative programming]] language which can be used to describe a presentation of text, images and video. An MHEG-5 application consists of a number of ''Scenes'' which the user of the application can move between. Each ''Scene'' lists the items of text and graphics to be presented and can contain blocks of [[procedural programming|procedural]] code which are executed in response to one of a predefined set of [[event driven programming|events]] such as keys being pressed, timers firing or content being successfully loaded into memory. These blocks of code consist of ''elementary actions'' which can perform operations such as changing the text displayed by a text [[object (computer science)|object]], or starting a video clip playing.

MHEG-5 specifies a hierarchy of classes that are available to the application author. Unlike in [[object oriented]] languages, it is not possible for new classes to be defined. The standard defines two representations of MHEG applications, one of which is textual and the other is represented in [[Abstract Syntax Notation One|ASN.1]]. Applications are normally written in the textual notation and then encoded into ASN.1 for interpretation by the MHEG ''engine''.

MHEG-5 is suited to programming [[interactive kiosk]]s and [[interactive television]] services.

== Use in other standards ==
MHEG-5 has been selected as the mandatory interactivity engine for [[CI+]] compliant TVs (and other CI+ devices).

== Profiles and commercial roll-out ==
The MHEG-5 language itself is just that, a language. To be useful in any particular context, the language needs to be [[profile (engineering)|profiled]].
A broadcast profile of the language has been standardized by [[ETSI]], forming ETSI standard ES 202 184.

===United Kingdom===
In the [[United Kingdom]], MHEG-5 is used to provide [[interactive television|interactive]] services for digital television such as the BBCs [[Ceefax]] replacement service, [[BBC Red Button]]. The full specification of how MHEG-5 is used in the context of the UK [[Freeview (UK)|Freeview]] platform is the [[UK Profile of MHEG-5]]. MHEG is also used on [[Freesat]] for its programming guide in addition to the DVB EIT, as opposed to the OpenTV platform used on Sky.

===New Zealand and Australia===
In [[New Zealand]], the same profile as in UK is used, with minor additions for the Maori language and its use of the ''guide'' key on ''certified'' Freeview receivers.  The ''guide'' receiver key is used to activate the MHEG-5 programming guide; this however disables use of the more compatible and faster loading DVB EIT guide feature.  In Australia, this guide practice was adopted for the phase 2 Freeview and [[Viewer Access Satellite Television|VAST]] receivers referenced by the label ''Freeview EPG''.

===Hong Kong===
In Hong Kong, [[Television Broadcasts Limited|TVB]] has also selected MHEG-5 for interactive services available on its digital-only channels.<ref>[http://www.tvb.com/affairs/faq/press/20071128_e.html MHEG-5 A Must To Enjoy “TVB Interactive” Services].</ref>

===Ireland===
Ireland has selected MHEG-5 (v1.06) middleware for interactive services as a recommended feature of its Minimum Receiver Requirements for DTT in Ireland.<ref>[http://www.digitaltelevision.ie/NR/rdonlyres/BFED0C82-501B-42E0-8F38-0789EA604497/0/MinimumReceiverRequirementsforDTTinIrelandv10.pdf Minimum Receiver Requirements for DTT in Ireland v1.0] {{webarchive|url=https://web.archive.org/web/20110721123629/http://www.digitaltelevision.ie/NR/rdonlyres/BFED0C82-501B-42E0-8F38-0789EA604497/0/MinimumReceiverRequirementsforDTTinIrelandv10.pdf |date=2011-07-21 }}.</ref> The name for Ireland's free digital service is [[Saorview]].

== Class hierarchy ==
[[File:Jerarquia.png]]<br />
Note: You can download the PDF version of above image from http://mheg5.net/down/class.pdf.

== See also ==
* [[Hybrid Broadcast Broadband TV]] (HbbTV), an alternative technology used for interactive television services via broadcasting and broadband communication media in some European countries.
* [[MediaHighway]], a proprietary middleware for interactive television owned by [[NDS Group|NDS]].
* [[Multimedia Home Platform]] (MHP), an alternative technology used for interactive television services in some European countries.

== References ==
{{Reflist}}

== External links ==
* {{Official website}}
{{List of International Electrotechnical Commission standards}}
{{DEFAULTSORT:Mheg-5}}

[[Category:Interactive television]]
[[Category:IEC standards]]
[[Category:ISO standards]]
[[Category:Hypermedia]]
[[Category:Multimedia]]