MHEG-5

Key takeaways

MHEG-5 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MHEG-5 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MHEG-5 from memory before moving on to harder problems.

Reference excerpt

MHEG-5, or ISO/IEC 13522–5, 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 and Freesat in the UK, Freeview in New Zealand, TVB in Hong Kong, Freeview in Australia, Saorview in Ireland and has been specified in South Africa. Recent 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 code which are executed in response to one of a predefined set of 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, 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 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 kiosks 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 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 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 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 VAST receivers referenced by the label Freeview EPG.

Hong Kong In Hong Kong, TVB has also selected MHEG-5 for interactive services available on its digital-only channels.

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. The name for Ireland's free digital service is Saorview.

Class hierarchy

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. Multimedia Home Platform (MHP), an alternative technology used for interactive television services in some European countries.

References

External links Official website

Worked examples

Example 1 — a first encounter with MHEG-5

Start with the simplest possible case. Write down what MHEG-5 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MHEG-5 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MHEG-5 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MHEG-5

In research: MHEG-5 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MHEG-5 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MHEG-5 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hypermedia, IEC standards, ISO standards, so understanding it makes those chapters shorter.
In everyday life: Look for MHEG-5 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study MHEG-5 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MHEG-5 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MHEG-5 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MHEG-5 in simple terms?

MHEG-5, or ISO/IEC 13522–5, 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.

Why does MHEG-5 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MHEG-5?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MHEG-5.