Web Information Systems and Technologies 2009


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Integration between Digital Terrestrial Television and Internet by means of a DVB-MHP web browser
Irene Amerini, Roberto Caldelli, Rudy Becarelli, Francesco Filippini, Giovanni Ballocca, Roberto Borri)
Lisbona 24 March 2009

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  • The outline of my presentation is the following:
    I’ll explain why the integration between Internet and Digital Terrestrial Television is necessary .
    I’ll briefly introduce the DTT and in particular the European standard for the DTT: the DVB-MHP standard
    Then I’ll explain how that integration is possible through the development of a web browser suitable through the use of a TV screen and a STB.
    A set-top box is a device that enables a television set to receive and decode digital television broadcasts.
    I’ll describe the system architecture and the prototype evaluation.
    Then I’ll give some conclusions.
  • Due to the fact that in Europe part of the Europe in particular in Italy (where I live) in 2012 there will be a switch-off from analog to digital signal
    There is a need of integration between Internet and DTT by means of a web browser.
    The solution proposed to pursue integration also permits to enrich the user experience in DTT environment permitting to reduce the digital divide to community not yet reached by broad-band services and helping
    isolated user group (due to economical and age reasons) to access informations and Internet services
    The main question is Why there is a need of integration between Internet and DTT by means of a web browser.
    The main reason is to reuse an already existing techonology (the DTT) and then
    build a multifunctional platform that provides an access to both Interactive TV services (already offered by that platform) and also to Internet services.
    Also in 2012 (two thousand and twelve) in Europe will be the complete transition from analog to digital signal then a few million of DTT terminal (set top box) will be present in European households.
  • Many standard exist to manage interactive and DTT.
    We focus our research on DVB-MHP standard
    The DVB-MHP standard is present in Europe etc…..
    MHP: interface between interactive digital applications and the terminal where these application run.
  • Two standard specification exist for the MHP: the MHP 1.0 and 1.1.
    The MHP 1.1 provides access to the web through the Internet Access Profile but few STBs support this profile,
    this kind of STB has higher price then STB MHP1.0 compliant so is not yet diffuse through the market.
    The MHP 1.0 make available two type of profile: Enhanced and Interactive. The second one permits the use of the return channel that is the transmission link from the STB
    to an external server or to the open Internet. (dial-up modem-telephone line).
    The idea behind this work is to provide the Internet access under MHP 1.0 profile.
    The MHP defines Java as interoperable application format. The application in DVB-MHP environment is named Xlet or DVB-J application.
    The Java runtime version used to develop MHP application is the 1.1.8 and some API are added (graphical API and API to dialog with the special device-STB)
    The Xlet can be embedded in STB or downloaded from an object carousel as it is an add-on application on the channel make avalaible from a broadcast
    MHP application is basically Java application named DVB-J (similar to the well known Applet for the web)
    this application runs on to java runtime environment 1.1 and the standard provide some API extension. Here there is a list.
    Broadcast TV signal
  • So how we can make this integration possible under the constraints imposed by the DVB-MHP standard?
    We develop a DVB-J application MHP 1.0 compliant, using the Java version 1.1.8 and the API extensions provide by the standard.
    Also we deal with a reduced interactivity (only the remote control at disposal) and a low screen resolution impose by the DTT platform.
    Also there is a constraint regarding the dimension, there is a need of a small memory footprint less then 1 Mbyte
    In this way this application can be linked to the TV broadcast instead of the device
  • Furthermore we can’t use an existing solution because the existing TV web browser are embedded (so aren’t device independent), or have custom content or haven’t an user interface.
    The browser for small device (cell-phone) has server side conversion and most of them are written in C C plus plus language (they arent Java application)
    Browsers Java exist but aren-t JDK 1.1.8 compliant
    Under these considerations and these constraints we develop an XHTML web browser as a DVB/J application named WebClimb
    We can’t use on existing TV web browser because most of them are embedded application, usually they are not Java and they present an user interface very row and often not usable.
    So on these of these basis (issue) we……
  • In this slide the system overview is depicted.
    The broadcast send the TV digital signal with the application linked to the channel.
    The application is loaded on the stb. Then the application is available to the user. The user can choose WebClimb application and the user can navigate on the open internet on the TV screen and through the return channel (that establish the HTTPConnection)
    I briefly show…..
    The broadcaster broadcasts the TV digital signal multiplexed with the MHP applications.
    The signal is received by a common antenna and it is rendered on the TV by the use of the STB.
  • Here I present the WebClimb System Architecture that can be split in three layer, Networking, Rendering, GUI.
    The main input of the system architecture is an URL that in input at the GUI layer pass trasparently to the other layer up to the Netwoking layer (LEIER) that resolve this URL, handle network communication and it is
    in charge of managing HTTP conncetion over the return channel.
    The output is the content of the specified URL.
    The output from the networking layer are the XHTML and CSS data and these data are the input to the Rendering layer than a data model has been created and a layout engine takes the data model
    (web content and format information) and displays the formatted content on the GUI.
    HTTP connection is established
  • Here there is the RenderingLayout layer flow representation.
    The documents obtained from the lower layer (Netowrking) are parsed by third party libraries (small dimension) then two data model are created then with an assignment algorithm a Decorated model is created. The ass. algorithm associates CSS style rule according to cascading and inheritance defines in CSS2 Spefication.
    The Layout Engine following the visual formatting model specification described by W3C, displays the formatted content on the screen through a positioning algorithm (normal flow, no floats and absolute positioning)
    Let’s see an example of these….
  • This is the decorated model with the XHTML element (tag) associate with the CSS element.
    All the element in the model know which are the right positions to fill in the Viewport (main window of the browser) due to the fact that are inline or block elements following the normal flow positioning scheme. Each XHTML tag are inline or block element according to the visual formatting model.
    At the root element correspond the containing block inside the Viewport.
    For example the tag a is an inline element and the rectangular block associated is laid horizontally after the previous element box, the div instead is a block element so the box is laid out vertically .
    Tree model
    The second element is the page.
    Each is sequentially located pass throgh the tree
    The first node is the page and then the other element. Img element that is located in inline mode. Then the others element are located following the block or inline modes.
  • The WebClimb user interface is presented in the figure.
    We design the UI with two navigation level the first manage the application user interface that it is the navigation toolbar and the color button toolbar, the second level is the navigation inside the viewport through which the user can move throghout a web documents. The user can switch from one to the other with the pressure of yellow key button of the remote control.
    We need to keep in mind that the TV remote control is the only device that has to be utilized to control the system at client side.
    The GUI provides other useful features such as the opportunity of adding a web page to bookmarks, and the zoom/in zoomout font size and a scrollbar when the viewport is smaller then the document’s initial containing block.
    The focus is moved over the icons of the navigation toolbar using the arrows left and right and that tha choice takes place with the OK button. Click the OK button to perform a link selection.
    Other functionalities have been implemented such as bookmark management and zoom-in zoom-out of the font size
  • For text editing or form compilation a virtual keyboard has been devised following the usability criteria described by Fondazione UGo Bordoni (line guide for the DTT application)
    Text input, for example to fill in a form a virtual keyboard has been implemented too.
    The vistual keyboard has been implemented on the basis of specified usability criteria.
    In particular letter or number selection is performed by using the arrow left and right/up and down and then the selection is performed by the OK button.
  • We have implemented a prototype of WebClimb browser and then the performance is evaluated in term of execution on commercial STBs.
    WebClimb behaviour has been verified on page of disparate categories:XHTML web pages
    The browser with its 900 kbytes footprint needs low memory requirements for execution and works on all STBs tested both for ethernet and modem connection
    Shows the same result in term of graphical element visualization on TV screen among different STBs.
    Memory capabilities
  • Here there is some WebClimb output for various XHTML web : XHTML google web pages and others……..
  • Sansevero country house
    General web page of a sort of turistic promotional web page where there is an high resolution image and a breaf description
  • Repubblica news web page
  • So we demonstrated that integration between TV and web is possible developing
    a DVB/MHP web browser, java based. The system architecture has been described and then evaluated giving positive results.
    We are working on compare …….
    How user evaluate WebClimb
  • Web Information Systems and Technologies 2009

    1. 1. Integration between Digital Terrestrial Television and Internet by means of a DVB-MHP web browser Irene Amerini, Roberto Caldelli, Rudy Becarelli, Francesco Filippini {irene.amerini, roberto.caldelli, rudy.becarelli, francesco filippini}@unifi.it Giovanni Ballocca, Roberto Borri {giovanni.ballocca, roberto.borri}@csp.it 24 March 2009
    2. 2. Outline • Why Integration? • Digital Terrestrial Television • How Integration is achieved • WebClimb system architecture • WebClimb prototype evaluation • Conclusions
    3. 3. Why Integration? • 2012: digital TV convergence in Europe (hundred of millions of terminals) • To enrich the user experience in DTT • Reduction of digital divide • A multifunctional platform that provides an access to both interactive TV and also to Internet services TV WEB BROWSER
    4. 4. Digital Terrestrial Television • Many standards exist (OCAP, ACAP, ISDB, DMB) • DVB-MHP: Europe, part of Asia, Latin America, some country of Africa DVB (Digital Video Broadcasting) consortium: standard for the broadcast transmission of digital terrestrial television. This system transmits compressed digital audio, video and other data in an MPEG transport stream. MHP (Multimedia Home Platform): open standard platform for interactive digital TV and multimedia services.
    5. 5.  MHP applications: DVB-J application or XLET embedded in STB or downloaded from an object carousel Digital Terrestrial Television • MHP 1.0 Enhanced Broadcast Profile Interactive Broadcast Profile (return channel) • MHP 1.1 Internet Access Profile a few STBs support such a profile, higher price PersonalJava ~Java 1.1.8 + Java TV API HAVi UI DAVIC API DVB API to provide Internet access under MHP 1.0 profile
    6. 6. How Integration is achieved (1/2) • Specs-Constraints: • MHP 1.0 • JDK 1.1.8 + Java TV, HAVi UI, DAVIC, DVB API • Reduced interactivity (only remote control) • Low screen resolution • Small memory footprint (<1Mbyte) • Downloaded from an object carousel as a normal Xlet (device independent) WebClimb XHTML web browser as a DVB-J application
    7. 7. ReturnReturn channelchannel WWW BROADCASTER The Infrastructure TV Digital SignalTV Digital Signal STB
    8. 8. WebClimb System Architecture GUI Rendering/Layout Networking • presentation • layout engine • parsing • HTTP Client (Apache) - HTTP/HTTPS connection over return channel • Ethernet/PPP Resolver - session management connection DVB API • URL Resolver URL XHTML CSS data display
    9. 9. System Architecture – Rendering/Layout (1/2) JTidy Visual formatting model specs W3C Assignment algorithm SACParser
    10. 10. System Architecture – Rendering/Layout (2/2) GUI Viewport Text paragraph Title h1 link CSS
    11. 11. System Architecture – GUI (1/2) • Two navigation levels: UI, Content Area
    12. 12. System Architecture – GUI (2/2) • Virtual keyboard • Remote control: key to key navigation
    13. 13. WebClimb evaluation • Test on various XHTML pages • Execution on commercial STBs • different model and brand (ADB, Humax, Elsag, TeleSystem) • Memory RAM 8Mbytes-64Mbytes • Modem, Ethernet connection or both Results • Clear visualization, correct character encoding and management of the graphical elements on the screen • Compatibility with respect to different model and brand STBs • 900 kbytes dimension
    14. 14. WebClimb evaluation • some examples……..
    15. 15. • some examples…….. WebClimb evaluation
    16. 16. WebClimb evaluation • some examples……..
    17. 17. WebClimb evaluation • some examples……..
    18. 18. Conclusions • Integration between TV and web • Development of a DVB-MHP web browser: WebClimb • Positive results of testing with different kinds of STBs Future Trends • Compare WebClimb functionalities with others DVB-MHP web browser on the market (preliminary test give positive results) • Total dimension optimization • A deeper evaluation of the usability
    19. 19. Integration between Digital Terrestrial Television and Internet by means of a DVB-MHP web browser Irene Amerini, Roberto Caldelli, Rudy Becarelli, Francesco Filippini {irene.amerini, roberto.caldelli, rudy.becarelli, francesco filippini}@unifi.it Giovanni Ballocca, Roberto Borri {giovanni.ballocca, roberto.borri}@csp.it 24 March 2009