income. However, both systems can be used. To
make the benefits (new channels, interactive
applications) offered by the digital system possible,
the TV viewers with analogical system need a new
equipment called set-top box. Set-top box is a device
which works connected to the TV and converts the
digital sign received from the provider to
audio/video that the analogical TV can exhibit. To
have the advantages offered by the digital TV, the
set-top box needs a software layer which connects
the hardware to the interactive applications called
middleware. The DTV Brazilian System middleware
is Ginga (Soares et. al, 2007; Souza et. al, 2007).
This paper proposes an extension to Ginga-NCL
middleware through implementation of a new
module incorporated to the Ginga Common Core
called Recommender. The Recommender module is
responsible for gather, store, process and
recommend TV programs to the TV viewer. To
develop the Recommender module, it was used the
Ginga-NCL middleware developed by PUC-RIO
(Pontifical Catholic University of Rio de Janeiro),
implemented in C/C++ language with source code
available under GPLv2 license and according with
the patterns defined by the Brazilian system digital
television (“Ginga-NCL Virtual” , 2009).
The rest of this paper is organized as follow:
section 2 presents related works, section 3 describes
the providers, section 4 presents a general view of
Ginga-NCL middleware and the extensions
proposed to support the recommendation system;
section 5 presents details of implementation and
connection of new modules to Ginga-NCL
middleware; section 6 details the experiences, the
simulation environment and the results and section 7
presents the conclusion.
2 RELATED WORKS
In the last years, many TV personalized systems
have been developed to help the viewers in face of
the increasing offer of new services. The first
recommendation systems used explicit approach to
register the viewer’s preferences. In the last years,
researches have been done aiming to infer
automatically the viewer’s preferences.
TV-Advisor (Xu et. al, 2002) uses explicit
techniques to create recommendation, demanding
the viewer to specify the interests to the
recommendation system.
PTV (Cotter and Smyth, 2000) is a system which
provides personalized recommendation to the viewer
based on the collaborative filtering approach. The
viewer’s preferences are recorded in an explicit way.
The Multi-Agent TV Recommender (Kurupati et.
al, 2001) matches both explicit and implicit methods
to store the viewer’s preferences and uses
collaborative filtering in the recommendation of TV
programs.
In (Ardisson et. al, 2001) a multi-agent
architecture for an adaptable EPG system is
presented. The viewer’s preferences depend on the
day and time he/she watches TV. The viewer’s
profile is generated using explicit and implicit
techniques.
AIMED (Hsu et. al, 2007) proposes a
recommendation mechanism that considers
tendencies like: mood, demographic information,
etc, to recommend programs. The approach used is
the hybrid approach based on the content filtering
methods and the collaborative filtering.
The Recommender TV system uses implicit
techniques to have the viewer’s profile. Implicit
techniques demand monitoring and analysis of the
viewer’s behavior background to have the profile.
3 SERVICE PROVIDER
This section presents important concepts related to
the service provider, how the digital sign
transmission is done and what information is
provided and the relation with the recommendation
system proposed in this paper.
Besides the transmission of audio and video, the
Brazilian system digital TV is supposed to send data
to the TV viewer. The service providers can send via
broadcast application written in Java
TM
known as
Xlets or NCL applications, and both of them are
defined in the television Brazilian system. Besides
the application, the providers send tables which
transport information to the set-top box. This section
gives details about two important tables to this
context, the EIT (Event Information Table) and the
SDT (Service description Table).
Open digital TV systems adopt the pattern
MPEG – 2 System – Transport Stream (ISO/IEC
13818-1,2008) to the elementary stream
multiplexing. To understand what the elementary
streams are, it is necessary to understand how the
digital sign construction is done. In the first place
the audio captured by the microphone and the video
captured by the camera are sent separately to the
audio codifier and to the video codifier. The stream
of bits codifiers created separately is called
elementary stream. Once they are multiplexed in an
only stream of bits, the elementary stream is entitled
SIGMAP 2009 - International Conference on Signal Processing and Multimedia Applications
150