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DVB-HTML a new standard? Part 1

Posted on July 10, 2002

in Commentary & Society

by Mark Bolton (mark_bolton)

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Mark Bolton

Member info | Full bio

User since: March 07, 2002

Last login: September 17, 2007

Articles written: 3

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

Mark Bolton is an engineer working on the development of Hi-Definition-Television (HDTV), who also has an active interest in the development of the internet through his company Boltonmedia

Currently based in Shanghai, China and actively developing websites in both English and Chinese whilst designing and developing new methods of viewing these websites

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why not normal xhtml?

Submitted by htd on July 15, 2002 - 07:26.

I see no point in modifying w3c standards in any way. Currently these settop-boxes are in development, meaning that browsers will become xhtml, DOM and CSS2 compliant when these boxes go public and widely available. Another standard helps nobody, it just needs new browsers which introduces new bugs and so forth.

To require valid code is a good thing, but to require valid adapted extra html code for dvb is crazy. many tv-stations currently host web, wap, teletext and the current dvb info for their customers. instead of letting them use their existing webenvironment they need to add another extra rendering-engine creating mhp code - insane i think. it would be better to force them into valid html homepages then the web and dvb users are happy and a standardscompliant browser can be used. What about Philips, Nokia and the others supporting Mozilla into getting fully compliant, instead of creating some proprierity settop boxes...

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Reply to: Why not normal HTML?

Submitted by mark_bolton on July 15, 2002 - 19:35.

There are a couple of reasons why the DVB could not use standard XHTML, the principle one being the requirement for extra modules and CSS statements to cover things like streaming broadcast events (Program generated pop-up information) which are syncronised by a signal sent with the television program. Also with MHP there is added functunality that allows content to be viewed over the top of other content. The added Viewport command gives precise control to the developer over the size of the window. In the second and third parts of the article (Comming soon) you will see that they have stuck to the XML (XHTML) and CSS2 models, but have added required functionallity to enable navigation by remote control. I am currently awaiting my development kit (which currently costs a fortune) which will allow me to do some testing, but i believe that valid XHTML will display correctly with a few tweaks to the CSS. One of the principle reasons for the article was to increase awareness of this new medium, and because I am one of the people developing the platforms to display MHP to see what the reaction of the web development community is? One thing that is required for MHP to become a useable technology is for there to be content available to view. Although the TV stations will be generating content it would be nice to be able to use the full functionallity of MHP by being able to browse the web as well!

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Reply to: Why not normal HTML?

Submitted by htd on July 16, 2002 - 04:14.

Well these are good reasons to extend xhtml for DVB. Anyway i think it can be done by the MHP-browser and serverside scripting to handle streaming events (Browser sends them, server handles them - new protocol instead of new html standard).

Being able to navigate with the remote control is more a point of user-interface design and hardware performance. Using e.g. Opera with Keyboard only works like a charm - with any (html)homepage...

If CSS tweaks are probably enough, they should submit a new @media type request to w3c being called MHP or whatever. Then their extended CSS can be used with standard xhtml pages having an adapted sub-stylesheet.

Making these boxes browse the real web would be cool, but what about swf pages, pdf documents, gif images and all the other stuff out there...

The point i see in creating a special MHP standard is to make it easier for tv-station people to create pages. That no specialists are needed to create server, pages and sync their content with the programme then. Maybe i'm missing some real important feature that mhp needs a new standard for, but currently i'm not aware of anything impossible with w3c standards - i will follow your future articles to figure that point out ;)

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@media and reasons for not using serverside script

Submitted by mark_bolton on July 16, 2002 - 07:19.

There is a new @media type being submitted, I believe it will be DVB-MHP media type.
 
There are reasons for not using serverside scripting, one of them being the use of xlet's it is a requirement that the complete application be downloaded and sometimes sitting in memory waiting for a command to run. This is done so that interactive content can be syncronised with television content. It would be no good if you needed to load some interactive content at a specific time in a television program, and when you request the application then you have to wait for the download. Instead what the MHP standard says is that any application must be able to be downloaded and then await a signal to open.
 
For instance, if watching a game of golf/football (soccer for the americans in the house)/rugby/tennis (Delete as appropriate) and you wanted to see the bio of a specific player, all the graphics and presentation for the interactive display would be resident in memory, the only request to the server would be for the actual bio..
 
Part 4 of the article will deal with the method of opening, loading, pausing, and killing a MHP application.

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ok, then

Submitted by htd on July 16, 2002 - 09:49.

i can't await real applications for this. maybe i should emigrate to brazil, they've got the MHP system soon and not to forget the girls there - hehe ;)

i still doubt that special standards are needed, but i will continue to read your series maybe i will see their necessity then.

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