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

 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

uros

hou

= 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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