INTEGRATION BETWEEN DIGITAL TERRESTRIAL TELEVISION

AND INTERNET BY MEANS OF A DVB-MHP WEB BROWSER

Irene Amerini, Roberto Caldelli, Rudy Becarelli, Francesco Filippini

MICC (Media Integration Communication Center), Univ. of Florence, Viale Morgagni 65, 50134 Florence, Italy

Giovanni Ballocca, Roberto Borri

CSP, Turin, Italy

Keywords:

Digital TV, XHTML, Web browser, DVB-MHP, Set-top-box, Java.

Abstract:

The process of digital TV convergence, expected in Europe to the end of 2012, makes desirable to develop a

system that can provide access to the Internet offering web content on a television screen. In this paper we

present WebClimb, a web browser that would pursue an effective integration of Digital Terrestrial Television

(DTT) and Internet in the DVB-MHP platform. WebClimb is a Java-based web browser and enables users

to browse the web interacting with an easy to use Graphical User Interface (GUI), driven by a TV remote

control. We explain the system architecture of this novel web browser and we evaluate the operating modes of

a WebClimb prototype, over commercial digital terrestrial set-top-boxes.

1 INTRODUCTION

The digitization and convergence between broadcast-

ing, telecommunications and the Internet are bringing

deep and rapid changes to broadcasting environment.

These changes introduce signiﬁcant opportunities for

broadcasting consumers in term of choice and access

to the content.

The broadcasting infrastructure, with the advent of

digital terrestrial television (DTT) in the ’90s, is en-

abled to provide access to telematic services and dis-

tribute interactive applications to communities not yet

reached by broadband services (e.g. people in rural

areas). All the tools and applications designed to en-

rich the user experience in the DTT suddenly become

a factor enabling a ﬁrst step in the reduction of the

digital divide, at least helping to bridge the gap sepa-

rating users groups (due, for example to economical,

cultural or age reasons) from the access to informa-

tion and communication technologies.

When digital TV convergence will be completed (in

Europe the completion of the transition from analog

to digital signal has been set to the end of 2012) a few

hundred of millions of digital terrestrial television ter-

minals will be present in the European households, so

it would be desirable to develop a multifunction plat-

form that can provide access to both interactive TV

and also to Internet services. In this paper we demon-

strate the feasibility of Internet and Digital Terrestrial

Televisionintegration proposing a web browserproto-

type which is able to access web content toward TV.

There are many standard to manage interactive and

digital terrestrial television technology and in our

work we focus on DVB (Digital Video Broadcast-

ing) standard. This standard is used in Europe, Asia,

Australia, part of Latin America and in some coun-

try of Africa. In other country others standard ex-

ist: OpenCable Application Platform (OCAP) and

the ATSC’s Advanced Common Application Platform

(ACAP) for the United States, Integrated Services

Digital Broadcasting (ISDB) is active in Japan, ﬁnally

DMB (Digital Multimedia Broadcasting) is used in

China. In 2000, the DVB consortium completed the

standardizationof an open standard platform for inter-

active digital TV and multimedia services called the

Multimedia Home Platform (MHP). MHP deﬁnes a

generic interface between interactive digital applica-

tions and the terminals where these applications run.

DVB has adopted Java as the interoperable applica-

tion format for the MHP, developing a version called

DVB-J that includes the core of the standard Java

language and provides extensions appropriate to the

broadcast TV environment. These extensions include

a suite of APIs that contains most of the Java TV API,

323

Amerini I., Caldelli R., Becarelli R., Filippini F., Ballocca G. and Borri R.

INTEGRATION BETWEEN DIGITAL TERRESTRIAL TELEVISION AND INTERNET BY MEANS OF A DVB-MHP WEB BROWSER.

DOI: 10.5220/0001837003230328

In Proceedings of the Fifth International Conference on Web Information Systems and Technologies (WEBIST 2009), page

ISBN: 978-989-8111-81-4

HAVi User Interface, DAVIC (Digital Audio Video

Council) APIs and DVB APIs. DVB also enclosed

a new application model, a security framework, and

a broadcast data transport system for the delivery of

MHP applications (also known as “Xlets”). A Xlet

can be either resident in the STB or downloaded from

an object carousel of a TV channel.

Two MHP speciﬁcation exists: MHP 1.0.x (DVB,

2003) and MHP 1.1.x (DVB, 2005). The MHP 1.0.x

included the deﬁnition of two proﬁles; the ﬁrst, the

Enhanced Broadcast proﬁle is the baseline proﬁle of

the MHP. It is intended for use in broadcast only sys-

tems where there is a unidirectional ﬂow of data to

the receiver. The second proﬁle is called the Interac-

tive Broadcast proﬁle and provides support for a bi-

directional data channel using the return channel sys-

tems currently deﬁned by DVB. The MHP 1.1 speci-

ﬁcation includes the deﬁnition of a new proﬁle called

the Internet Access proﬁle and a new optional content

format called DVB-HTML (Gil et al., 2002). The In-

ternet Access proﬁle is intended to provide access to

the most common types of Internet services, as cur-

rently found on the Internet i.e. WWW and e-mail.

Today set-top-boxes on the market give support only

for MHP 1.0, so there are no boxes that support the

Internet Access Proﬁle. A possible solution is to al-

low the user to download from the TV object carousel

a web browser as a DVB-J application.

In this paper such a solution is presented providing the

Internet access functionality on DVB-MHP platform.

We develop a DVB-J application, MHP 1.0.x compli-

ant, available for all the STBs today on the market or

already previously acquired. This application, named

WebClimb, permits to access the Internet through the

use of the return channel provided by the Interactive

Broadcast Proﬁle. WebClimb could be embedded on

the set-top-box itself or downloaded from the broad-

cast TV carousel similarly to an usual MHP applica-

tion.

The paper is organized as it follows. After review-

ing some related works in Section 2, we present in

Section 3 the proposed system architecture. Finally

the application’s prototype is evaluated and the results

are presented in Section 4, conclusions are provided

in Section 5.

2 RELATED WORKS

This section explores the related works concerning

web browser for digital terrestrial television.

Some DVB-MHP commercial applications exist,

named Interactive TV platforms, that manage XML

pages and act as a browser.

Example of these are: Pontegra HTML browser de-

veloped from the Nionex company, Goonie Browser

(NordCom Interactive), Ace Browser (Ortikon Inter-

active), Soﬁa Backstage BrowserPlatform (Soﬁa Dig-

ital), Evo Browser (Espial Escape) and Yambo pro-

vided by CINECA. Such platforms were born mainly

for the development of MHP services by acting as

an engine to render applications written by using

standard well-known languages such as HTML or

XHTML and avoiding to deal with Java programming

language (as explained in Section 1). Limitations to

these system are that some of them are not broadcast

application; in fact they are only embedded in STB

and the browser is not an add-on application on the

channel. Others applications don’t present a GUI in-

terface and some of them display a subset of DVB-

HTML format or non-standard XML pages.

In (Vuorimaa et al., 2002) a Java based XML browser

named X-Smiles is presented, intended both for desk-

top use and embedded network devices, like palm-

top, mobile and TV, to support multimedia services.

There is an attempt for porting a limited version of X-

Smiles on a MHP compliant digital television set-top-

boxes but the current state of this attempt is unknown.

In (Cho and Park, 2005) the authors design an inte-

grated web browser for digital home networking and

digital data broadcasting based on ACAP standard in-

stead of DVB standard. In (Ferretti et al., 2007), the

authors introduce a system to access the WWW that

requires the usage of a server-side application gate-

way, acting as a web-spider, to collect a predeﬁned

set of web contents and reformatting them to ﬁt the

constraints of the TV environment. This approach

is useful in the production and management of the

so called “walled garden services”, where the broad-

caster or service operator is able to control and vali-

date the contents to be accessed by the user but can

become extremely cumbersome in the access to the

open Internet.

So these issues inﬂuenced our thinking in develop-

ing WebClimb that is, as we said in Section 1, a

DVB-J application, MHP 1.0.x compliant, and can

be downloaded by the broadcast TV object carousel

or, alternatively, can be embedded in a STB, and lo-

cally executed on each STB. It permits to properly

manage web contents, without a server-side conver-

sion, and visualize them on a TV screen, by means

of a Graphic User Interface (GUI). WebClimb is a

basically XHTML browser and assures a ﬁne visu-

alization for XHTML web page but it can also man-

age HTML pages composed by XHTML tag (W3C,

2000).

In particular during WebClimb design, speciﬁc care

has been dedicated to consider the limitations im-

WEBIST 2009 - 5th International Conference on Web Information Systems and Technologies

324

Figure 1: An use case.

posed by the TV set: low screen resolution and re-

duced interactivity in order to develop an intuitive

graphical user interface.

3 SYSTEM ARCHITECTURE

In Figure 1 an use case of the whole process is de-

picted: a TV broadcaster transmits the WebClimb ap-

plication multiplexed on its TV signal to all the re-

ceiving STBs.

An user, by selecting that speciﬁc TV channel sup-

porting such an Internet service, can access to the list

of applications provided by the channel and choose

WebClimb to navigate the web via the return channel

(e.g. telephone line) and the remote control unit of the

STB. For instance, if the user, while looking at a foot-

ball match, wants to know information about a certain

football player, he can switch on WebClimb applica-

tion and, comfortably sitting on his armchair, he can

access to the net for searching.

WebClimb browser system architecture is a stack

composed by three layers:

• Networking

• Rendering/Layout

• GUI (Graphical User Interface)

Each layer is described in detail hereafter.

3.1 Networking

The Networking layer is a module to handle net-

work communication and it is in charge of manag-

ing HTTP/HTTPS connection over return channel. In

detail, these layer takes as input an URL (Uniform

Resource Locator) or URI (Uniform Resource Iden-

tiﬁer) and outputs the content of the speciﬁed URL

passing through the following steps: URL Resolver,

Ethernet/PPP Resolver, HTTPClient. The ﬁrst one is

a module that resolves URL and URI and returns a

stream that allows the client to send and receive data.

The Ethernet/PPP Resolver hides the type of data link

protocol (Ethernet or PPP) used for the return channel

connection to the higher level, and handles the session

management connection through the DVB API.

The third module is the HTTPClient which imple-

ments the application level protocol HTTP. HTTP-

Client, a third party library made available by

Apache (http://hc.apache.org/httpclient-3.x), is em-

ployed since support for HTTP is not mandatory in

DVB-MHP platform, as speciﬁed in (DVB, 2003).

3.2 Rendering/Layout

In Figure 2 the steps composing Rendering/Layout

layer is displayed.

Figure 2: The Rendering/Layout layer ﬂow representation.

The ﬁrst step consists in the document parsing. The

input data streams coming from the lower layer are

parsed and converted in a easily handled tree data

structure (see the ﬂowchart branches in Figure 2

called DOMParser and CSSParser).

Two kinds of input are handled: the web page in

XHTML or HTML format and the CSS style sheets

linked to the web page. Then for our purpose, there

is the need of a parser that take as input XHTML or

CSS formats and outputs a Document Object Model

(DOM). JTidy (http://jtidy.sourceforge.net) has been

chosen to parse XHTML format thanks to his small

code dimension in terms of memory occupation and

to his capacity of manage non-standard XML like

HTML.

The XHTMLModel in Figure 3 is created

through one-to-one association with a DOM

model obtained through the use of JTidy

parser. Also SACParser (Simple API for CSS,

http://www.w3.org/Style/CSS/SAC), a third party

CSS parser library, has been select to generate a

Document Object Model style tree called CSSModel

(Figure 4).

After that, the data model (XHTMLModel) is deco-

rated with CSS information through the assignment

INTEGRATION BETWEEN DIGITAL TERRESTRIAL TELEVISION AND INTERNET BY MEANS OF A DVB-MHP

WEB BROWSER

325

Figure 3: XHTML web page example and on the right the

XHTMLModel.

Figure 4: CSS style sheet linked to XHTML and the CSS-

Model.

algorithm till to obtain a XHTML+CSS Model (Fig-

ure 5). The assignment algorithm links CSS selector

to elements in the XHTML Model and associates CSS

style rule composed by property’s value according to

cascading (weight-origin of a style sheet and speci-

ﬁcity of a selector) and inheritance rules deﬁned in

the Cascading Style Sheet level 2 Speciﬁcation (W3C,

1998).

After XHTML data parsing has been performed and

data model has been created, it is necessary to display

the data on the screen so the core of the web browser

architecture, the layout engine, is built. A layout

engine, or rendering engine, is a module that takes

web content (such as XHTML, image ﬁles, etc.) and

format information (such as CSS) (the XHTML+CSS

Model in Figure 5), and displays the formatted con-

tent on the screen, following the visual formatting

model speciﬁcation described in CSS Style Sheet

Speciﬁcation (W3C, 1998). All the elements in the

XHTML+CSS Model know which are the right posi-

tions (coordinate points) to ﬁll in the main window

on the screen (viewport) due to the fact that are inline

or block elements following the normal ﬂow position-

ing scheme. Furthermore each element also knows

its own dimensions obtained from dimensions of the

inner block that composes a containing block. For ex-

ample the tag a is an inline element, and so the rect-

angular box associated is laid horizontally, after the

sibling element box; the tag div instead is a block ele-

ment so the box is laid out the previous box vertically.

All the boxes are attached to the containing block in-

side the viewport. WebClimb’s viewport resolution

is 640× 480 pixel, due to the low resolution of TV

screen, so when the viewport is smaller then the doc-

ument’s initial containing block, the browser offers a

scrolling mechanism.

Additionally all elements in the XHTML+CSS Model

are responsible for rendering themselves drawing ap-

propriate widgets, using the Viewport GUI Toolkit,

based on AWT and HAVi User Interface API, imple-

mented to satisfy graphical browser’s need.

Figure 5: The XHTML+CSS Model and its visualization on

the viewport.

3.3 Graphical User Interface

Focusing on usability and yielding the user interface

as intuitive as possible, we have kept in mind that the

TV remote control is the only device that has to be

utilized to control the system at client side. Conse-

quently the implementation of all functions that are

usually providedby a mouse (pointing, clicking, drag-

ging) have to be replaced by actions on the remote

control buttons.

In particular, for text editing, a virtual keyboard in-

terface has been devised, according to the criteria de-

scribed in (Ambiente Digitale, 2005). The navigation

pointer on the keyboard is discrete (key-to-key). The

user navigates the virtual keyboard on the TV screen

using the arrows keys of the interactive keypad and

selects the desired alpha-numeric character pressing

the OK button. Once he has selected the character,

this appears on the text box area.

The WebClimb GUI (see Figure 6) has two navigation

levels: the ﬁrst concerning application user interface

and the second concerning the navigation inside the

content area (viewport) through which the user can

move throughout a web document. The users can

switch from one to the other with the pressure of the

WEBIST 2009 - 5th International Conference on Web Information Systems and Technologies

326

Figure 6: Digital television GUI: 1. Main Menu; 2. Content

area (Viewport); 3. Navigation Toolbar; 4. Color Button

Toolbar (the yellow button enables link navigation within

the viewport); 5. Highlight; 6. Scrollbar

yellow key button of the remote control (see Figure 6

“Browse link ON/OFF”).

The focus point of the ﬁrst level of the GUI’s com-

ponents is controlled with the arrow buttons of the

remote control and selection is made with OK but-

ton. As shown in Figure 6 the top of the GUI con-

tains the navigation toolbar which shows the current

URL and home-page, back and forward buttons as it

usually happens in a common browser interface. In

the center of the GUI there is the viewport. Dragging

function through viewport’s scrollabar is performed

through the arrow up/down key on the remote control.

At the bottom of the GUI there are the color buttons

in horizontal position in the same color sequence as in

the remote control to satisﬁed the criteria of effective-

ness and usability (Ambiente Digitale, 2005). Some

functionalities must be present in all digital terrestrial

television applications such as exit the application, go

back to TV stream and a help for the user. All these

and other functionality are associated at some color

buttons in WebClimb: red button exits the applica-

tion, green button activates the menu, yellow button

enables switching of the two navigation levels (as pre-

viously explained) and blue button allows to go back

to the TV stream.

Inside the viewport (second navigation level) some

GUI components are focusable elements (link, text

input, radio button, check box etc.); the user can pass

through each focusable element by means of the up-

down arrow of the remote control. With the OK but-

ton one element is chosen; for example if a XHTML

form text input is chosen a virtual keyboard for text

editing appear. If the OK button is pressed again the

the inserted text is sent according as POST or GET

method of the tag form. The control remains inside

the viewport until yellow button is pressed again.

Finally the minimum font sizing (18pt), which is re-

quired in digital terrestrial application to avoid graph-

ical ﬂickering effect on the screen has been respected.

Figure 7: WebClimb output for the New York Times mobile

version web site

The GUI provides other useful features such as the

opportunity of adding a web page to bookmarks and

the zoom-in/zoom-outfont size as a ﬁt-to-width prop-

erty that automatically reformats and re-sizes content

to the viewport.

4 PROTOTYPE AND

APPLICATION

We have implemented a prototype of WebClimb

browser following the Model View Controller (MVC)

architectural pattern (Gamma et al., 1994). In our

application, the Model is represented by Facade-

Model class and the main View is the MBScrollCon-

tainer class that represents the viewport on the tele-

vision screen (as described in the previous section

and shown in Figure 6). The Controller is an object

that, through the controllerLogic() method, set a new

URL to the FacadeModel; then a stream is opened

and through the use of the parser the data model is

created. Once the model is created the data model is

visited through the Visitor design pattern; whenever

each element of the model is visited a draw() method

is performed and, if necessary, proper widgets are pic-

tured.

The WebClimb prototype performance is evaluated in

term of execution on commercial STBs. WebClimb

behavior has been veriﬁed on pages of disparate cate-

gories (from XHTML web page designed for PC web

browser to mobile XHTML web page) giving positive

results generally. In Figure 7 a rendering example is

presented. WebClimb shows properly web page’s con-

tent information and has a clear visualization, due to

right handle of character encoding and also due to the

arrangement of the graphical elements on the screen.

WebClimb has been evaluated on a real DVB-T sys-

tem, downloading it on commercial STBs by means

of a TV broadcasting platform. To test WebClimb’s

compatibility, the prototype has been veriﬁed on the

INTEGRATION BETWEEN DIGITAL TERRESTRIAL TELEVISION AND INTERNET BY MEANS OF A DVB-MHP

WEB BROWSER

327

following STBs: DiPro DP-001, ADB X75-T, Elsag

IDTV 1000, Telesystem TS7.0DT and Humax DTT-

3500. The ﬁrst and the second are two ADB’s differ-

ent models of STBs. ADB is one of the main producer

of STBs, with over 10 million digital set-top-boxes

sold worldwide, so this test was particularly funda-

mental to check WebClimb compatibility. The main

differences among these STBs are the memory, which

ranges from 8 MByte memory to 64 Mbyte, and the

Internet connection that in some case take place with

a modem connection and in others with ethernet and

modem connection.

From this experimentrises up that WebClimb browser,

with its 900K byte footprint, needs low memory re-

quirements for execution and works on all STBs

tested, both for ethernet and modem connection. Web-

Climb shows the same result in term of graphical el-

ements visualization on TV screen among different

STBs. So the test performed on commercial STBs

prove the effectiveness of our prototype demonstrat-

ing its efﬁciency on different model and brand.

5 CONCLUSIONS

In this paper we presented the WebClimb browser, a

Java-based DVB-MHP web browser for digital terres-

trial television STBs. The system model architecture

has been described and then evaluated in order to ver-

ify its performance. We developed a browser that can

be broadcast via a TV carousel or embedded on a STB

and locally executed; it collects web contents and dis-

plays them without asking for reformatting of such a

content from the server side.

Experimental tests over commercial STBs have given

positive results especially in prospect of a real usage

of the system. The WebClimb browser, as well, can

function as Interactive TV platform enabled broad-

casters and network operators to create content for en-

hanced and Interactive Television using standard web

tools.

We are working on compare WebClimb functionali-

ties with others DVB-MHP web browsers today on

the market, like those described in Section 2. In the

near future WebClimb will be optimized in term of di-

mension and an additional positioning scheme of vi-

sual formattingmodel will be implemented (ﬂoats and

absolute positioning).

ACKNOWLEDGEMENTS

The authors would like to thank Tuscany Region

(Italy) for supporting the DTT Competence Center

which has carried out such a research.

REFERENCES

Ambiente Digitale, F. U. B. (2005). [Italian Version] Rac-

comandazioni per le interfacce dei servizi interattivi

della televisione digitale.

Cho, S. and Park, J.-S. (2005). Design of an integrated

web browser for digital tvs. Advanced Communica-

tion Technology, 2005, ICACT 2005. The 7th Interna-

tional Conference on, 2:1089–1092.

DVB (2003). DVB Multimedia Home Platform (MHP)

Speciﬁcation 1.0.3, ETSI.

DVB (2005). DVB Multimedia Home Platform (MHP)

Speciﬁcation 1.1.2, ETSI.

Ferretti, S., Roccetti, M., and Palazzi, C. (2007). Web

content and adaptation for idtv: One step forward in

the mediamorphosis process toward personal-tv. Ad-

vances in Multimedia, 2007:1–13.

Gamma, E., Helm, R., Johnson, R., and Vlissides, J.

(1994). Design Patterns: Elements of Reusable

Object-Oriented Software.

Gil, A., Pazos, J., Lopez, C., Lopez, J., Rubio, R., Ramos,

M., and Diaz, R. (2002). Surﬁng the web on tv: the

mhp approach. Multimedia and Expo, 2002. ICME

’02. Proceedings. 2002 IEEE International Confer-

ence on, 2:285–288 vol.2.

Vuorimaa, P., Ropponen, T., von Knorring, N., and

Honkala, M. (2002). A java based xml browser for

consumer devices. In SAC ’02: Proceedings of the

2002 ACM symposium on Applied computing, pages

1094–1099, New York, NY, USA. ACM.

W3C (1998). Cascading Style Sheets, level 2 CSS2 Speciﬁ-

cation.

W3C (2000). XHTML 1.0: Extensible HyperText Markup

Language.

WEBIST 2009 - 5th International Conference on Web Information Systems and Technologies

328