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Abstract—This article proposes an open flexible and
composable framework for the development, the delivery and the
presentation of t-learning courses in interactive digital TV (iDTV).
The framework is divided into two main parts: the production side,
where the course is prepared and the client side, where it is
presented on iDTV, and where the user can perform the
educational interaction. The course production is supported by an
ad-hoc designed authoring tool, while the runtime user interaction
on iDTV is managed by a multimedia course player providing
personalization services and a library of educational and
entertainment elements and services.
Index Terms— authoring tool, iDTV, MHP, t-learning
I. INTRODUCTION
elevision has had a long history of performing an
educational function for the mass audience, typically by
broadcasting culturally-relevant movies, documentaries and
news as well as educational programs. The idea of Distance
Learning through a TV blossomed extensively in particular as a
complementary educational option besides PC-based e-learning
and traditional analogue TV educational programs. In particular,
TV-based interactive education promises a huge potential due
This work was supported by ELU (Enhanced Learning Unlimited) project,
which is funded by the European Commission.
Francesco Bellotti is with the ELIOS Lab, Department of Biophysical and
Electronic Engineering (DIBE), University of Genoa (e-mail:
franz@elios.unige.it).
Stefanos Vrochidis is working as a Research Associate within the
Informatics and Telematics Institute, Thessaloniki, Greece, (e-mail:
stefanos@iti.gr).
Eirini Parissi is working as a Research Assistant within the Informatics and
Telematics Institute, Thessaloniki, Greece, (e-mail: parissi@iti.gr).
Pascal Lhoas, Master in IT, is working as a project manager within the
Center of IT Innovation of the Public Research Center Henri Tudor,
Luxembourg (pascal.lhoas@tudor.lu).
Damien Mathevon is with the Center of IT innovation as engineer
specialized in multimedia and iDTV within the Public Research Center Henri
Tudor, Luxembourg (damien.mathevon@tudor.lu).
Matteo Pellegrino is a PhD student in the ELIOS Lab, Department of
Biophysical and Electronic Engineering (DIBE), University of Genoa (e-mail:
pellegrino@elios.unige.it).
Giancarlo Bo is with the Giunti Labs S.r.l., Sestri Levante, Italy (e-mail:
g.bo@giuntilabs.it).
Ioannis Kompatsiaris is working as a Senior Researcher within the
Informatics and Telematics Institute, Thessaloniki, Greece, (e-mail:
ikom@iti.gr).
Publisher Identification Number 1558-7908-062008-04
to its ability to support interactivity, while compensating for the
low penetration of Internet-enabled computers in comparison
with the penetration of a TV in a household.
“T-learning” was the new term, which prevailed for the
definition of TV-based interactive learning [1]. The first forms
of learning with interactive digital TV (iDTV) have been little
more than modified or enhanced videoconferencing. Today,
iDTV platforms for learning provide a large amount of
audiovisual and educational content to the viewer through
interactive and content personalization. iDTV is considered as
the convergence of television and computer technologies by
encompassing three important features typical of
computer-based technologies [2], such as interactivity,
personalization and digitization.
Digital television mostly relies on the Digital Video
Broadcasting (DVB) standard, characterized as DVB-T for
terrestrial, DVB-S for Satellite and DVB-C for Cable
transmissions. DVB has been defined by a consortium of public
and private organizations in the iDTV sector [3].
In the DVB schema, the digital TV signal is transmitted as a
stream of MPEG-2 data known as a transport stream. This
stream consists of a set of sub-streams (elementary streams),
where each sub-stream can contain MPEG-2 encoded audio,
MPEG-2 encoded video or data encapsulated in MPEG-2
stream.
Fig. 1: overall broadcasting system for digital TV.
Subsequently, the transport stream is passed to the
multiplexer and then to a Radio Frequency (RF) transmitter in
order to be broadcasted. The overall broadcasting system for
digital TV is illustrated in Figure 1. The received signal is
demodulated and afterwards it has to be decoded appropriately.
The common TV sets are manufactured to deal with analogue
signals. Hence, a device called Set Top Box (STB) is used to
transform the digital signal. Moreover, it also provides a
middleware, based on an embedded Operating System (OS),
F. Bellotti, S. Vrochidis, E. Parissi, P. Lhoas, D. Mathevon, M. Pellegrino, G. Bo and I. Kompatsiaris
A T-learning Courses Development and
Presentation Framework
T
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which is an execution environment for running the interactive
applications that are broadcast in a channel together with the
main audiovisual stream. Execution environments are standard
and the most common are: the European Multimedia Home
Platform (MHP), the American Open Cable Application
Platform (OCAP) and DTV Application Software Environment
(DASE), the Japanese STD-B23/STD-B24. Since MHP is the
standard in Europe and a subset of it, the Globally Executable
MHP (GEM), is becoming the common reference world-wide,
in this article we focus on MHP.
MHP is the middleware system for interactive TV
development designed by the DVB Project [4]. The first draft of
MHP was released in August 1999 and the first version of MHP
1.0 was approved by DVB in February 2000. MHP offers a
standard platform for application developers. Applications are
written in Java and HTML, so they don't depend on any single
hardware platform or operating system. Due to the iDTV’s
special context, MHP-Java applications are slightly different
from normal Java applications. However due to the similarities
with Java applets, MHP-Java applications are called Xlets.
On the one hand, MHP Java limitations are mainly related to
the constraints given by the STB’s hardware and OS in terms of
computational power, memory size, storage, communication
facilities, screen resolution, font and colour availability and
their size is severely constrained by the limited bandwidth
available. On the other hand, MHP provides support for those
special features which are essential in the digital TV world such
as low-level access to the transport stream, service information
access, and support for the specialized graphics model of the
digital TV. MHP can be extensively exploited by t-learning as it
offers the proper middleware for learning interactive
applications.
Fig. 2: General Framework for the development and delivery of a t-learning
course.
The purpose of this article is to propose an open flexible
platform for the development of t-learning courses by exploiting
the available iDTV technologies in a pedagogical way.
The article is organized as follows: section II presents the
proposed framework, the t-learning course structure and the
main components involved. Subsequently, section III describes
the development of t-learning courses, by analyzing the
authoring tool, while section IV deals with the client side, where
the Course Multimedia Player is presented. Eventually, section
V concludes the paper.
II. GENERAL OVERVIEW
A. General Framework
The proposed architecture, which is illustrated in Figure 2 is
split in two parts: the production side where the content is
prepared and the receiver side where the course is presented to
the viewer through the appropriate terminal.
The production side is the area where the course content is
created. As the course development is based on the requirement
of reusability, the content is structured in the appropriate format
so it is playable by a Course Multimedia Player which is also
transmitted with the course package.
The educational A/V stream for the t-learning course is built
by a TV producer, while the contents are developed in the
authoring tool by the educators. The content including games,
images and text is used for the development of personalized
courses and can be retrieved from a server where learning
resources are stored. Eventual A/V-application synchronization
is achieved with the aid of authoring tool as well, where the
content created is matched on specific time stamps inserted in
the A/V stream. Subsequently, the A/V stream is fed into the
MPEG2 encoder while the content produced by the authoring
tool and the Course Player Xlet are inserted into the object
carousel. In this way the sub-streams are constructed and then
multiplexed to form the final transport stream, which is
broadcast.
The signal is received at the receiver side and processed by
the STB where the A/V stream and the applications are restored
from the transport stream. The Xlet that contains the t-learning
course runs on the STB MHP middleware presenting the
content of the course. The existence of an Internet IP return
channel on the STB allows the use of on-demand features.
Through this return channel it is possible to send requests
regarding the retrieval of additional learning resources as well
as information about the viewer in order to support more
advanced personalization features.
B. T-learning Course Structure
The course creation is based on the structure of a Learning
Object (LO) [5]. A Learning Object can be defined as both the
basic unit of a learning experience and as a small, atomic chunk
of learning that can be reused in different context. In other
words, the LO structure is actually an aggregation of items,
which grants a customizable and flexible reuse.
Following this definition and by adopting the LO model
specifically developed for t-learning courses, it is possible to
integrate several multimedia components and thus create
educational material and content suitable for distribution
through an iDTV infrastructure. Thanks to this model the
content author can manage separately the various components,
as well as the parameters that define their behavior, and then
generate in a simple way the final LO (course) in the form of an
XML script.
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This XML script describes the t-learning course and is
interpreted at runtime by the Course Multimedia Player on the
STB. It is Object Oriented, which is close to human reasoning,
easy to agree and specify. Moreover, Object Orientation is well
supported through powerful development tools (e.g. UML). The
script is event-oriented as well, which is particularly suited for
the TV environment, where an application may be synchronized
with the underlying A/V stream.
The main objects nested in the script are called cards and can
contain either a multimedia page (MPage) , which may consist
of texts, images, audios and buttons accompanied by the TV
stream in various formats (e.g. inside a quarter frame), or an
interactive edutainment unit, such as a game. As multimedia
page is considered a normal page that could appear in the TV
screen while games include quizzes, puzzles and so on.
In order to support reusability, the above items (Mpage and
games) are implemented as specific templates, which are fully
configurable in terms of contents and appearence. These
templates can thus be instantiated one or more time in a course.
Configuration files also support personalization. That is, the
properties of a single template instance can further be
parametrized according to the dynamic (i.e. evolving even
during the course) profile of the end-user. This is achieved
through the introduction of parametrical tags that can be
parameterized by the course content author on the parameters
defined by the Personalizer’s module which is described in the
next section.
The XML script specifies the cards that constitute a course,
their content (in terms of the above mentioned templates), and
their time scheduling, since several of them may be
synchronized with the A/V stream., Synchronization is
expressed in terms of time triggers that are inserted in the A/V
stream and are able to trigger relevant cards, as it is specified in
the script.
The script also contains information about global variables,
that can be defined by the author and serve to store, for the
whole length of a course, course-specific information that are
typically used to schedule the triggering of the cards according
to the preferences, needs and/or other parameters of the current
user.
Finally, through the script the course author can also
specificy the aspect and the functionalities of the navigation bar,
which is displayed as a stripe at the bottom (or top) of the screen
and is controlled through the 4 iDTV colour buttons (red, green,
yellow, blue). Sample functionalities can be offered by the
navigation bar include: personalization settings, choice of
course categories, exit/hiding/restoring of cards, helps, further
info, other advanced services. Functionalities are grouped in 4
clusters, each one of which is mapped to (and accessed through,
by end-users) one the four coloured buttons. A course may have
several different navigation bar configurations that change
dynamically during the course itself (e.g. in different cards,
different categories, when no card is on display) in order to
provide the most suited, context-aware support. These different
configurations are to be specified by the author in the course
script.
C. Multimedia Page
A multimedia page is the most common item used in a card to
create a course. It allows the content creator to freely locate
static assets as titles, pictures, text zones and also interactive
assets as buttons.
Figure 3 shows a multimedia page displayed by transparency
on a full screen TV-program.
The Mpage is template-based in order to allow reusability.
Such page can be shown at runtime by using the specific
MHP-java classes which read the respective property file. The
property file supports the customization and the personalization
of the page including text fonts, text boxes size and location, etc.
A sample Mpage as it presented to the viewer through the
iDTV screen is illustrated in 0.
Figure 3: Instance of a Multimedia Page.
D. Interactive Edutainment units
Games in iDTV could play an important role in t-learning
although today are used mostly for entertainment. Nowadays, a
considerable number of games exist for iDTV, covering various
categories, such as arcade, adventure, puzzle and educational
games. Quizzes, multiple-choice and memory games could
increase the interest of the viewer-learner supporting the
concept of relaxed-learning that seems suited to TV.
T-learning has the ambition of creating educational games for
a wide range of users, in particular those with limited attitude to
computers. The games are considered as an integral part of a
t-learning course as they could support the learning procedure
involving a wide audience through challenges and engaging
activities that are anyway able to meet the typical user need for
relax and sympathy.
The games that can be included in a course are based on
specific configurable templates and form a Java class package,
which is structured as follows. Game Template is a Java class
that abstracts general game functionalities. Subclasses of Game
Template are the game typologies offered by the standard game
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library. Sample game typologies include: Memory, Puzzles,
Visual Quiz, Couples, etc. The Actual games played by the
end-users will be instances of such subclasses.
From a software point of view, Game Templates is a
hierarchy of Java classes. Game Template is the abstract
superclass. The game typologies are the concrete subclasses.
The actual games running on the STB will be instances of
such game typologies. Every game instance will come boundled
with its own resources (i.e. images, animations, fonts, graphics,
text, etc.).
The actual games running on the STB will be instances of
such game typologies. Every game instance will come boundled
with its own resources (i.e. images, animations, fonts, graphics,
text, etc.).
On the production side (i.e. off-line), an author – even not
skilled in computer science – will be able to create instances of
the various game typologies (i.e. actual games that will be
broadcast and played) by editing parameters (e.g. number of
available lives) and inserting contents (e.g. images, graphics,
questions, animations, etc.). This can be done .manually, or,
much more efficiently, thorugh an ad-hoc developed authoring
tool, that we will describe in the next section.
Figure 4: Instances of Games.
The runtime system running on the STB manages the
life-cycle of every card and its contained elements, games
included (i.e. loading, starting, managing its exit and possibly
forcing a pause and/or stop), according to what specified by the
script. A game will be able itself to recursively manage other
games (i.e. building trees of games, according to the user
preferences).
In Figure 4, sample instances of Quiz, Couples, Memory and
Puzzle games are illustrated in the way they appear in the TV
screen.
E. Personalization in t-learning courses
In general, the final goal of personalized learning is to
provide a learning path that is matched to the learner's needs and
abilities, resulting in a more efficient and high quality learning
process. In order to obtain this matching of learner’s profile and
objectives, current learning context and available pedagogical
resources, a well-defined description of each component
involved in the process is needed, with specific focus on the user
model. An additional interesting aspect of the personalization
process is that, once the user model has been identified, the
accuracy of the personalization can be iteratively improved with
time, as more dynamic data are collected and stored regarding
the ongoing interactions of the user with the system and the
continuous monitoring and re-assessment of the user’s
satisfaction. This also allows for a classification and
“clustering” of learners [6].
Personalization in terms of t-Learning implies that a potential
iDTV learner can easily be offered on his/her TV equipment a
selection of available pedagogical contents and services
according to his/her interests, skills and preferences.
The module, which is responsible for allowing
personalization in the proposed t-learning framework, is called
Personalizer. This module is capable of user tracking, taking
into account long term features as age, sex, etc., and session
features, like score in a game, difficulty course level and other
course related preferences.
The Personalizer keeps track of the dynamic user profile (e.g.
current values of the user interaction, such as score, what pages
have already been visited, what quizzes, etc.) and of the
persistent user profile (e.g. preferences, etc.). Before finishing,
every card is responsible for updating the Personalizer. For
instance, the results of a questionnaire may change so the global
score of the course has to be updated.
III. PRODUCTION SIDE
The main component involved in the production side is the
authoring tool. This tool is composed of two logical parts: the
content insertion and configuration tool and the script builder.
The former is responsible for the template configuration
while the latter deals with the definition of the sequence of the
course based on time and logical events. The output of this tool
is composed of the sequence script in XML format, as described
in the previous section, the property files of the templates and
the resources (images, audio files, etc) involved, in a structure
package. The whole production chain is illustrated in Figure 5.
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Fig. 5: Production Chain.
A. Authoring Tool
The proposed authoring tool is an efficient environment
where the author is capable of creating educative courses for
iDTV. It consists mainly of the two logical aforementioned
parts: the course sequence and events definition part, where the
structure of the course is defined based on event and the
templates configuration part, which is responsible for the
customization of existing templates like multimedia pages and
games.
The tool provides a clear graphical interface (Figure 6) which
supports features as drag and drop, image previews and object
designing. The concept of the tool is based on the creation of
Learning Objects in a form of XML script and on the
configuration of existing templates.
A typical t-learning course is based on a learning object and
can contain the following main items:
• Globals: used for global tags definition
• Variables: for the definition of variables used within the
object. It is possible also to declare here all the variables that has
to be used inside events
• Cards: used for creating and setting up cards which
correspond to a set of templates as Multimedia pages,
presentations and games, as described in section II
• Categories: used for creating and setting up categories,
which correspond to different course paths, and those related
events that define both the user interaction and how the course
will be presented to the learner. As categories can be considered
levels of difficulty (i.e. hard, easy) or other domain categories
(i.e. History, Architecture, etc)
The part of the authoring tool dedicated to the creation of
categories provides authors with an intuitive way for defining
events lists (temporal or logical) linked to each category. The
tool handles the definition of all the supported
operations/instructions by using an XSD schema in a “secure”
mode, thus avoiding the risk for the author to generate invalid
XML files.
Each category is graphically represented as a tree, this way
giving to the author a visual and easy perception of the sequence
and articulation of the events. Other supported features - as drag
and drop cards, a temporal line where the events can be
sequenced and the possibility to play a video content (.avi) –
further allow for an easy creation of categories (Figure 6). As a
result, the tool provides a “What You See Is What You Get”
(WYSIWYG) environment where authors will not have to be
concerned by the internal structure and the constraints imposed
by the XML script.
Fig. 6: Authoring Tool interface with events and timeline.
The part of the tool which is responsible for the configuration
of the cards provides a friendly environment where existing
templates can be customized. These templates include
Multimedia pages with images, buttons and text, multimedia
presentations and games, which can be configured appropriately
in terms of appearance, fonts, screen mode and content (Fig. 7).
The idea of templates allows full reusage of existing code and
material which is very important in the case of iDTV where the
bandwidth for data transmission and the STB memory are
limited. Hence, this authoring tool is a proper solution for
t-learning as it has been developed to tackle the special needs
and constraints of the iDTV and to offer educational oriented
content creation.
The proposed templates have been designed in a way that
satisfies the needs of the learners while the full configuration
capability, which can also be based on conditions, is an added
pedagogical value as it supports the creation of personalized
courses.
Fig. 7: Authoring Tool interface with templates configuration.
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Fig. 8: Authoring Tool interface with navigation bar configuration.
Furthermore the tool supports a standard way of designing
cards and templates based on a predefined style which will set a
default for many configuration values and let the author specify
only the main ones.
This feature increases the usability of the tool as it makes it
even more user-friendly and usable also by end-users who do
not intent to waste a lot of time for creating the course and
designing new multimedia pages.
In addition, the authoring tool provides a functionality that
allows the author to customize the navigation bar by offering a
proper interface with menus preview and add-remove menu
items capability. Figure 8 illustrates the above functionality.
Pedagogists and teaching professional will be interested in
such a tool as it provides a user-friendly and course oriented
environment for the creation of iDTV supported pedagogical
content without requiring programming skills. In addition, this
tool could be a very convenient and innovative solution for
professional content providers who are interested in creating
learning content, as at this point there is no authoring software in
the market that supports the development of education oriented
content for iDTV.
IV. CLIENT SIDE
The Course Multimedia Player (CMP) is the t-learning client
software that reads the data generated by the authoring tools to
present the final course. It runs on the user MHP STB to allow
interactivity between the learner and the application.
Two main steps in the playing process can be identified as
shown in Figure 9:
• Building the interactive application.
• Executing the application with the video.
A. Building the interactive application
As explained in previous section, the xml script contains all
required data to instantiate a course. By reading this xml
description file, the multimedia player creates the static part of
the course (each page/card) and the dynamic part where
navigation, personalized path based on the user profile, and
synchronization with the TV-program are involved.
Fig. 9: Building the application in the Client Side.
B. Executing the Application with the video
When a T-Learning application is launched by a TV viewer,
the Course Multimedia Player parses the corresponding scripts
to instantiate the T-learning course. Subsequently, the following
components are involved:
• Graphical Rendering Manager
• Navigation Manager
• Synchronization Manager
• Personalisation Manager
• Interactivity Manager
1) Graphical Rendering Manager
First, the Multimedia Player is responsible for the graphical
interface. It displays all the course components and manages the
video stream rendering. For instance, following the course
creator choice or according to the Personalizer’s values, each
course screen can be displayed in 3 different modes: full Screen
(FS), full Screen with TV picture (FSTV) and Stripe (S) (Fig.
10).
Fig. 10: Card Display Modalities: Stripe, Full Screen with TV Picture, and Full
Screen Instance of a Multimedia Page.
2) Navigation Manager (personalised)
Interpreted at runtime, the course path can change following
several rules from the personalization manager (0). This path
can also be influenced by the synchronization manager or the
user interaction. It allows a dynamic adaptation of the learning
path. At a higher level, different paths may be specified by the
author for different user categories, as shown in Fig. 11.
3) Synchronisation Manager
Synchronization is realized between the TV-program and the
application. Indeed, regarding the timeline, some time triggers
(they may correspond to events such as beginning of the first
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part, end of the second part) are listened by the synchronization
manager that can thus take adequate actions. For instance, start
an application or change the section in a course.
Fig. 11: Different Course paths paths – due to a user’s personal values - for 3
different user categories. Circles correspond to cards.
If we consider a TV-program, which is related to tourism,
with a first part dedicated to Paris and a second part dedicated to
London, the synchronization mechanism will send an event to
the course to change the relative data from Paris to London. The
T-learning course may be thus context-aware regarding the
video stream.
4) Personalisation Manager
The Personalizer keeps track of the dynamic user profile (e.g.
current values of the user interaction, such as score, what pages
have already been visited, what quizzes, etc.) and of the
persistent user profile (e.g. preferences, age, etc.). Not only
will this module be responsible for updating the Personalizer’s
data, but it will also orient the user by taking decision at runtime
as explained in the subsection II-E.
5) Interactivity Manager
Finally, the Course Multimedia Player manages Interactivity.
Interactivity can be seen in two levels:
• Local interactivity: it is provided by programmable
components that enable the action of the user on visible parts of
the screen and change the behavior/settings/appearence of the
objects that are displayed, without the need of a return channel.
The user can access local interactivity simply through her/his
remote control.
• Server interactivity: same as local interactivity but the
actions of the user are sent to a server as “requests” via a
physical return channel [c.f. General Framework Part] and the
behavior of the displayed objects is modified through the
reception of “commands” from the servers, application servers
or broadcast server. For instance, the server interactivity can be
used to store general data in a centralized way or also to request
additional information on a given topic.
V. RELATED WORK
Although the research and development in iDTV-based
t-learning is rather limited up to date, some interesting
approaches have been presented.
An interesting approach was the technological framework for
TV supported collaborative learning proposed in [7]. In this
approach t-learning contents are created with appropriate tools
and delivered however personalization was not applied and the
fully automatic creation of the course was not supported. In a
more recent work [8] a more general framework is presented
with content creation based on XML structures and templates.
Although this work has been an interesting basis it is still
inadequate to deal with learning oriented content as it serves
more general purposes. Furthermore the two aforementioned
approaches haven’t been tested thoroughly in iDTV or
simulation environment, as no specific results are presented.
Considering the market approach, nowadays there are
considerable tools available, both open source and commercial,
like Composer [9] and Grins Pro Editor [10]. More specifically,
the former is capable of creating content in NCL [11] language
for Ginga middleware while the latter is a SMIL [12] editor.
Such tools could have been used for the creation of pedagogical
content due to their flexibility, however, as they are not
education-oriented, they would fail to satisfy the needs of
pedagogues.
VI. CONCLUSION
In this article a flexible framework for the creation and
display of t-learning content on iDTV was presented. The
proposed platform exploits the available iDTV technologies in
order to provide support for the development and presentation
of t-learning courses satisfying the pedagogical requirements.
During the course creation, a clear structure for the content is
defined, while the template logic allows reusability, which is a
big advantage at the iDTV world where the available bandwidth
and the storage capabilities of the STBs are limited and the
production costs are high and the time-to-market short.
Moreover, the configurability option allows the insertion of
personalization, which is considered as an added pedagogical
value.
This template-based approach allows the creation of flexible,
standard courses that are interpreted by a multimedia course
player running on a STB, The player interprets the course
configuration script and accordingly presents the structure
content to the viewer and manages her/his interaction through
the remote control.
Another advantage of the proposed framework is the
extensibility as it is possible to support services on demand, also
IEEE MULTIDISCIPLINARY ENGINEERING EDUCATION MAGAZINE, VOL. 3, NO. 3, SEPTEMBER 2008
1558-7908 © 2008 IEEE Education Society Students Activities Committee (EdSocSAC)
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by exploiting the return channel of the STB, and including other
kinds of contents, such as virtual avatars and more complex
games.
ACKNOWLEDGMENT
This work is supported by the project ELU (Enhanced
Learning Unlimited) [13], which is funded by the European
Commission.
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