THE NEW DIGITAL TELEVISION AND THE INTERACTIVITY
IN ITS MULTIMEDIA APPLICATIONS
Finding the Interactivity Using a Low Cost Solution
José Luis Redondo García, José Luis González-Sánchez, Alfonso Gazo Cervero
and Javier Corral-García
Department of Computer Science, Universidad de Extremadura, Escuela Politécnica, Cáceres, Spain
Keywords: Interactive Digital Television, DVB, DVB-H, MHP, Return Channel, OpenTV, IP Television, iDesigner,
Osmosys.
Abstract: The new interactive digital television, based on transmission standards like DVB-T, offers an interesting
variety of services to both producers and consumers. This technology requires special decoders (STB’s),
which implement an intermediary software layer (MHP) that is able to execute applications. In order to
achieve the interactivity of these applications, STB’s must have what is known as return channel.
To implement all this theoretical content we have created a scenario for interactive MHP applications using
the decoder Strong SRT 5510, trying to show that it is possible to build low cost solutions. With this
infrastructure, UEX-TVi has been developed. Students at university can use it to access to the topics of
every subject, make test and quizzes, and see Web Pages on TV. The potential of the iTV is clearly
demonstrated.
Finally, the role that MHP will play in the future has been analysed, as well as the importance of the arrival
of the new IP Television.
1 INTRODUCTION
In only a few years, television has become the most
important media without any doubt. Watching
television is one of the most frequent activities we
usually do every day. All this issues are turning
television into the third factor of socialization
together with family and school.
Changes in the world of telecommunications,
improvements of satellite Networks, the new
interactive digital TV, etc. are doing that we cannot
think in the same terms that we did in the past.
Specifically, innovations that have more impact
in this global society may be interactive applications
on the TV, use of Internet with the remote control or
access to on-line demand programs (VOD), which
will allow the user to choose what he wants to watch
at any given time. This rapid development of
technology brings us to a world of amazing
opportunities with great potential for interactivity
and participation.
In this context, this paper tries to evaluate the
available tools for the development and deployment
of these technologies, and test their ability to bring
us the promised services at a low cost. Also with the
work we have done (the most important, UEX-TVi
implementation) the different degrees of interactivity
on television existing today are showed, and
interesting conclusions will be found.
2 CONSIDERED SCENARIOS
Before starting this research it is important to choose
the topology for the scenario where interactive TV
applications will be loaded. The aim is to create an
infrastructure where we can execute and debug
programs. In our case these programs will be
developed for MHP platforms although other
alternatives like OpenTV has been considered
(Fagerqvist & Marcussen, 2000). Available options
are varied, but almost all of them are too expensive
for the university. However we have found average
solutions for working with these technologies
without paying an exorbitant amount of money.
2.1 Professional Equipment
They are the highest-quality devices and allow us to
make test like service providers really do. They are
much more reliable than the rest of alternatives, and
167
Luis Redondo García J., Luis González-Sánchez J., Gazo Cervero A. and Corral-García J. (2009).
THE NEW DIGITAL TELEVISION AND THE INTERACTIVITY IN ITS MULTIMEDIA APPLICATIONS - Finding the Interactivity Using a Low Cost
Solution.
In Proceedings of the International Conference on Signal Processing and Multimedia Applications, pages 167-172
DOI: 10.5220/0002230601670172
Copyright
c
SciTePress
we can make real measurements of range, bandwidth
channel, noise, quality of signal… that cannot be
made with lower cost materials.
In the list of devices of this group there are
multiplexers, object carousel generators, modulators,
amplifiers... The modulator costs around 3000 € and
the other has similar prices. It’s very expensive for
research groups.
2.2 PCI Cards + Carrousel Generators
This option has the advantage of supporting a great
number of the capabilities offered by professional
equipments. There is a decrease in the costs
associated to this alternative because we do not use
some devices such as amplifiers, and other ones are
simplified, like modulators (multiple entries not
required). They are unnecessary to work in a
laboratory where the emitter is so near to the
receiver. But the price is still considerable.
Figure 1: PCI card scenario.
Let us see the parts of this scenario:
Software for application development: Java
development environments like Eclipse.
TS Generators: they are software multiplexers.
There are free alternatives like JustDVB-IT
2.0 (Cineca, 2009) or Opencaster.
Modulators DVB-H: they receive multiplexed
data, then module and sent it over the coaxial
cable connector.
2.3 Serial Port Connection
Trying to achieve lower costs, we will reduce the
necessary hardware for the scenario. For this, we
have found an alternative that does not need the
mentioned PCI card, and uses a RS-232 port from
our PC.
A clear disadvantage is that the serial cable
interface is an old technology, that has a very low
transfer rate in order to transmit audio / video.
Also we only send the MHP applications; the
audio / video is captured directly from the TV signal
that reaches our homes. This issue explain the fact
that there is no possible synchronization between
applications and video/audio.
However, we will be able to debug and run MHP
applications properly, and it is a cheap solution (we
Figure 2: Serial port.
will only have to buy the receiver an the serial cable
because the great majority of computers is provided
with this type of connection.)
2.4 Using Emulators
STB emulators are programs designed to simulate
the internal workings of a conventional STB, and
display the TV output on the screen of our PC.
The advantage is that it is the cheapest option of
all. Applications are loaded quickly and safely.
But it is not possible to study real parameters like
loading times and delivery times like in a real STB.
There are also some incompatibilities between the
different implementations of the MHP standard.
If we want to choose one of the emulators
available today, we may use the proprietary ones
(usually included with a development environment
and they only work for applications that have been
created in it), like Osmosys SDK, NSD MHDK,
IDesigner... By the other hand there are free
Emulators that can be a good starting point to work
with MHP. But they are insufficient when more
serious applications are executed (e.g. XletTView).
2.5 Using Ethernet Interface
This is a solution very similar to using the serial
port, but in this case the applications are sent to the
STB by an Ethernet cable.
But before using the return channel, we need to
send (using the signal input of conventional coaxial
cable) a page containing an index, which lists all the
services and applications available via Ethernet.
The basic advantage is that most computers have
this type of connection. Also, hardware costs are
reduced dramatically and the bandwidth of the
Ethernet cable is bigger than in the old RS-232
interface.
But many STB's on the market do not have
Figure 3: Showing Ethernet scenario.
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Ethernet. Also, as the first index page has to come
before anything else to our receiver via the TV
signal, we are still dependent on a scheme of
conventional emission. Finally, there are security
problems: applications that come to our STB from
the Ethernet interface are allowed to execute on it.
2.6 Virtual Test Centers
Thanks to the MHP-KDB project (MHP-KDB
group, 2009) there are some centres where we can
test our developments. It is possible to send
applications to these remote laboratories to be
executed in any of the available STB's.
A main advantage of this alternative is that it is
free of charge. Also all the process is performed in
real STB’s so the results are more reliable.
Therefore this option is important for debugging
tasks and never for complete implementations
because we have to apply for using the service, and
there is limited time of use per day.
3 CREATING THE SCENARIO
Once we have done the necessary inquiries about
possible schemas to use, we are going to explain the
process of build the scenario that will be used to
develop the applications (UEX TVi) and perform
appropriate tests.
Figure 4: A full view of our scenario.
3.1 The Set Top Box
As was previously advanced, we have chosen the
SRT 5510 distributed by Strong.
There are many reasons for choosing this brand and
model. One of them is that the STB is among the
Figure 5: Decoder used for the research.
few in the market with MHP 1.1.X. Also, it supports
e-cards, and the return channel is based on Ethernet.
It has an average price (about 85 €).
3.2 Sending Data to the Receiver
Osmosys SDK has some applications to load MHP
programs using the serial port. Decoders that are
internally compatible with Osmosys libraries can use
this software. Our STB is one of them.
This software consists of two separate but related
programs:
The first one, "STBProxy", creates a proxy on
the serial port to send data from PC to STB.
The second one, "STBUpload” is the
responsible for sending all the files of the
application we want to execute, pause, stop...
We will see more details later.
This program has a license that is acquired when
buying any ABD development decoder or the SDK
Osmosys. Luckily, we are allowed to use it by
Osmosys under non-distribution conditions and for
research purposes. It only works on Windows
platforms, so a possible starting point for future
researches can be the development of a free version
of this product to run in other platforms.
3.3 Other Necessary Components
Apart from the decoder, we need a TV with euro-
connector (in our case a Sony Bravia) a PC for
sending the data to the decoder, and a TV aerial to
receive TV signal.
3.4 Connection of the Components
Here are listed the steps to be done:
Connect the cable between the STB and the
television input.
Connect the coaxial cable (with the TV signal),
into the appropriate port on the back of the
STB.
Connect the serial cable at the back of the STB,
and the opposite end at the RS-232 port of our
computer.
Connect the STB to a router or gateway.
3.5 Configuration of the PC
First, the STBProxy program must be executed:
stbproxy.exe -com 1 -port 4403 -log
milog.txt
In this case there are three parameters:
The serial port number where STB is connected
(e.g. COM 1).
The port number of the machine to mount the
proxy on (e.g. 4403).
A log file to store a list of the actions performed
on the proxy.
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Then, when trying to send an MHP application,
program STBUpload is used:
stbupload.exe localhost:4403
test.descriptionfile application –exec
The parameters of this command are:
Number of the port where the proxy has been
mounted previously.
Configuration File. Some of the parameters are:
name, control, bound, priority, visibility, main
class...
Folder where the MHP application to load is
located.
3.6 Setting up the STB
We must modify a flag stored inside the STB, which
indicates the mode of execution of MHP
applications. If it is enabled, the decoder sends by
the serial port all console messages (errors,
exceptions, printed codes...) that are produced
during the lifetime of the application. The
instructions to enable "Debugging Mode" are fairly
simple. First of all, run the program STBProxy and
then, load STBconfig with “-debug” flag:
stbconfig.exe localhost:4403 –debug
A message will appear on the console showing
the success of this operation.
4 RESULTS: UEX-TVI
Reading some papers (Peng & Vuorimaa, 2000) and
other documentation, especially Steve’s Web Page
(Morris, 2009) we have implemented our own
application, UEX-TVI. These are the main objetives:
Obtaining a useful application for students at
university. They will be able to access to the
documents of any particular course using the
iTV, make quizzes about these contents, and
view Web pages on TV.
Promoting new iTV researches in this
university.
Checking the functionality provided by the
standard profile: we must be able to run
multimedia applications in the MHP STB.
This will be demonstrated by creating the
menu that shows the content of every course.
Checking the functionality provided by
enhanced interactivity profile and interactivity
profile. The objective is studying how a user
sends information back to the station provider.
We will do this by implementing a test to
evaluate the contents they have learned before.
Checking the functionality provided by Internet
profile. We will do this by implementing a
simple Web browser.
4.1 Economic Viability Study
Development environments (Eclipse) and libraries
“MHPstub” (Steven Morris, 2000) are free. The
Osmosys application has been gently provided for
research purposes, the computer used belongs to the
university, and there is a TV in our research group’s
lab; no additional money is needed for these issues.
Despite this, the decoder costs approximately 80
€. We also need a RS-232 null modem cable (10 €),
and a SCART one (€ 3). 93 € is really a very little
amount of money, what is very positive.
It is clear that researchers do not receive any
remuneration for their work. But if any software
company had developed this project, this would be
very different. Taking into account that we have
been working approximately 1320 hours:
1320hours × 20
E
uros
hou
r
= 26400Euros
(1)
This gives an idea of the work we have made.
4.2 Showing the Results
Now we are going to show UEX-TVI. On this way
we can clearly verify if the objectives proposed in
the early stages have been achieved. A console for
debugging appears after the application is loaded:
Figure 6: Debug console.
If we press the loading button, the main menu
will be shown. Now we can choose the more
suitable option between the alternatives (Theoretical
content, Quiz, Web Browser, Video Mode and Exit.)
Figure 7: Main Menu.
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Selecting the “theoretical content” option, some
pages about the world of interactive television will
be displayed. For future works it is easy to change
the contents maintaining the same structure.
Figure 8: Theoretical contents (full screen mode).
If we choose the “Quiz” option, we have to try to
answer every question on the TV screen. All of them
are related to the theoretical contents that users have
read previously. There is also an explanatory picture.
Figure 9: Screen showing the quiz (1/4 screen mode).
The users can choose the option they consider the
best by clicking on one of the four buttons on the
right. The application will automatically show a
message (wrong or right answer) and continue with
the next question.
Figure 10: Message showing the answer was good.
“Theoretical content” and “Quiz” menus can be
executed in two video modes: full screen mode
(figure X-1), and 1/4 screen mode (figure X). We
can change from one to another mode with “Video
Mode” button.
Finally we have the Web browser. To call it
“viewer” rather than “web browser” is more
appropriate, because it is not yet capable of
managing the HTML hyperlinks so we cannot jump
from one document to another. However, it allows
the user to look up pages on Internet, and display
them on the TV screen, interpreting simple line
breaks, horizontal lines, headers and labels. First of
all when clicking on the “Open Web Page” a text
box and a virtual keyboard (MHP-KDB, 2009) will
appear on the screen. We must enter a valid URL
and then the website will be displayed.
Figure 11: Virtual Keyboard for HTML viewer.
5 CONCLUSIONS
As we can see, we have fulfilled the desired
objectives:
We have got an iTV application that runs on
most of the STB's, with a professional
multimedia graphic interface.
With the implementation of “Theoretical
contents” and “The Quiz” menus we have
demonstrated that we can create useful
educational tools for the new iTV scenario.
We have also worked with the interactivity that
digital television platforms promise: the
answers introduced by the user during the
Quiz are sent back to the same computer that
served the iTV application previously. In this
machine all the data can be saved and used in
various ways, e.g. modifying the application
we are broadcasting depending on the results.
The Internet has been brought to television. It
has been a very rudimentary experiment, but it
is valid to convince us that soon we will visit
any Web page using the remote control of our
STB.
The problem comes when realizing that MHP
does not have enough support in most of countries.
For example the Spanish government can offer new
services using iTV, like applications for finding
jobs. It would be also interesting to reduce the prices
of Interactive STB.
Furthermore, MHP allows conditional service
access: so you could enjoy football channels, good
series, etc. paying a small fee. This idea is working
well in Italy, because many corporations consider
this kind of business interesting. Other options are
trying to finance some developing groups to make
tutorials and better resources. Also, a part of the
frequency spectrum can be reserved for testing
purposes. On this way licenses to researchers would
be easier to obtain.
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6 IDEAS FOR THE FUTURE:
IPTV + MHP
The unidirectional transmission schema of the
terrestrial TV cannot support the new services that
are going to arrive.
By other side, words like IPTV are starting to
appear everywhere. IPTV is the acronym for Internet
Protocol Television. This definition is used to refer
to the transmission of the TV signal using IP, the
Internet’s network protocol. How will they change
the world of digital television?
6.1 IPTV
IPTV environments are similar to pay-per-view
platforms, like cable or satellite ones. The network
operator controls the service. It is responsible for
ensuring that the end user is receiving the signal.
This allows the service provider to manage and
control the signal quality, the kind of the offered
services, and the access to them.
To have or not to have the control over the
quality of the signal becomes one of the most
important elements that differentiates IPTV from
Internet Television. This allows the service provider
to ensure both signal quality and bandwidth
minimum (best services, no cuts, no pixelled images,
etc). However, to ensure this signal quality, the
operator must use a closed network infrastructure.
This involves big economical investments.
6.2 Internet Television
The technologies used by Internet Television are
basically the same than in IPTV environments
(MPEG4, WMV, etc.). The main difference is that
contents are delivered from the provider to the end
user via the Internet. Therefore, there is no control
over the transport network. This gap makes it
difficult to develop a conventional business model
like it could be done in the IPTV World.
Then, Internet Television is an open model in
which anyone can create contents (film, home video,
advertisement, etc.) and make them available to
other users in the way they want.
6.3 MHP in this New Approach
These IP technologies are getting more important
day by day, but MHP has still a very interesting role
providing an adequate platform to execute the
Internet protocols that IPTV and Internet Television
use. First, some parameters can be loaded using the
terrestrial channel as it used to be. Then, MHP
applications can establish a connection using the
TCP / IP return channel with any of the providers of
digital IP television.
.
Figure 12: IPTV and MHP in the future.
ACKNOWLEDGEMENTS
Special thanks to organizations and companies that
have contributed to the success of this investigation:
Atos Origin. (www.es.atosorigin.com/es-es/)
Maat Knowledge. (www.maat-g.com)
Mit-Xperts (www.mit-xperts.com/)
REFERENCES
C. Peng and P. Vuorimaa, 2001. "Digital Television
Application Manager" Conference for IEEE in 2001.
M. Fagerqvist and A. Marcussen, 2000. Application and
System Migration from OpenTV to DVB-MHP. PhD
Thesis.
WiMAX Forum, 2005. Fixed, nomadic, portable and
mobile applications for 802.16-2004 and 802.16e
WiMAX networks. www.wimaxforum.org
MHP Group, Accessed 2009. The MHP guide. www.mhp-
knowledgebase.org/publ/mhp-guide.pdf
Steven Morris, Accessed 2009. The MHP Tutorial.
http://interactivetvweb.org/.
MHP-KDB project group, Accesed 2009. The MHP
Knowledgebase. www.mhp-knowledgebase.org/
Cineca, Accessed 2009. JustDvb-It 2.0.
www.cineca.tv/labs/mhplab/JustDVb-It2.0.html
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