Dvb Html A New Standard Part 1

Digital televisions capable of displaying high resolution images are currently being developed for the consumer market. Some of these televisions are truly digital in nature, employing new methods of image projection such as LCOS, DLP, LCD and others. Other televisions will use the standard CRT but employ digital decoding equipment and new display driver technology which enables display of 800 x 600 resolution. Consumers will be able to view the internet and many other things as well. The applications of these new technologies include:

General Information:

• Telephony / Visiophony
• Browsing the WEB
• Interactive shopping/ E-commerce
• Online printed media (on demand or broadcast)
• Location based broadcasting services, etc

Entertainment:

• Plain TV and Radio
• Program related services (e.g. lyrics, cover of CD's, E-commerce,etc)
• On line streaming video "events" (sports, etc..)
• Audio/Video/Games on-demand,
• Interactive TV , etc

Business:

• Mobile office
• WEB- office Desk
• Virtual work-group, including video-conferencing, and big file downloading
• Order information : for travels, documents, tickets, etc.,
• Narrowcast business TV
• Medical imagery & Remote diagnosis, etc

How will these new applications be implemented?

Multimedia Home Platform (MHP) is one of the standards which will be utilised by a set top box or integrated digital television. Other standards in development include ATSC, DAVIC One comment recently on the MHP website in their FAQ section

there is the "Internet" profile, allowing MHP boxes to run Internet based content. This profile, involving significant HTML and other protocol, remains to be defined and technical work is currently proceeding on this issue. MHP 1.1 (all three profiles) was published by ETSI on the 14th November 2001

Contained with in the MHP standard is a proposed DVB-HTML which is based on XML but has it's own DOM and doctype declaration.

What does this mean for Content Providers, Web authors?

As DVB aims at a true horizontal market for the whole TV transmission chain, it considers this fact (That web authors need to tailor their content to differing browsers due to the non-compliance with W3C specifications) as established, and it's commercial requirements are to mandate the rejection of non-conformant content

So as to obey the DVB commercial requirement on rejection of non-conformant content by MHP implementations, DVB-HTML requires the "validation" of any documents that are signalled (in the broadcast stream or the file itself) as being of the DVB-HTML application type.

Reading from the above this means that any internet documents accessed by the MHP system have to comply with and validate against the DVB-HTML DTD or they will be rejected. However the DVB-HTML language complies with the XHTML Modularisation W3C Recommendation, so the step for most should not be too great.

Technologies used

Within the MHP specification the following technologies are to be supported:

• XHTML
• CSS Level 2 (Modified for DVB-CSS)
• DOM (Modified for DVB-HTML)
• ECMAScript
• XML 1.0

Comment

Because the adoption of a single standard world-wide for the application of interactive television has not been done, DVB-MHP is only one of the current standards being developed. This may mean that there will be regional differences in the standard used to display internet information on digital networks. If an application is to be developed (i.e. an e-commerce site) that requires a broad audience then it will require browser sniffing to identify if the user is using DVB-MHP, ATSC, DAVIC, or a standard internet browser. And subsequent redirection or dynamic writing of the page will be required.

The second article in this series will examine the DTD requirements and the modules included, excluded and added for DVB-HTML.

References

• EBU Technical Review - XML technologies in Broadcasting
• DVB-MHP Website
• MHP1.1 Specification