Vol.2 No.2
June 15, 2006
Editorial (pp097-097)
I. K. Ibrahim
Research articles: Content Adaptation Based Approach for Ubiquitous
Multimedia (pp098-0111) H.-P. Wang, Z.-W. Yu X.-S. Zhou, T. Zhang, and D. Xiang
Content adaptation is playing an important role in
ubiquitous multimedia, however it is a challenging work due to the high
degree of dynamism and heterogeneity of the ubiquitous computing
environments, where hundreds of devices provide information, and
thousands of terminals access these information. Recently, some
researchers proposed to address this issue by dynamically organizing
services or components into customized applications at runtime. However,
due to the maintenance of the dependencies between services or
components, this kind of system becomes more complicated with the growth
of the system scale. Programming for these systems is also error-prone.
This paper discusses the issues of content adaptation based approach for
ubiquitous multimedia, and presents a prototype system, called UbiCon
system. By abstracting media streams into generic CONTENT entities, the
system provides a simple and powerful means for services to operate
media stream. The CONTENT is dynamically created by the system at
runtime, and essentially has local association with related services. As
a result, the CONTENT is also used as a loosely coupling method for
cooperating associated services. By abstracting services with a T model,
the services can effectively cooperate together with other services. As
a result, a collection of sophisticated applications can be built with
this simple and effective services model.
Content Adaptation on mobile
devices using MPEG-21 (pp112-123) A. A.
Sofokleous and M. C. Angelides Content authors pursue the creation of
mobile content that is ubiquitous in nature, i.e. published once only
but being available anywhere, anytime, on any device. However, mobile
content must accommodate varying resource constraints on different
devices such as reduced resolution, processing power, memory and network
bandwidth. In this chapter, we discuss those issues that are pertinent
to multimedia content adaptation across different devices with reference
to MPEG-21’s Digital Item Adaptation for mobile devices. In particular,
we consider how the range of aspects that affect a mobile usage
environment, i.e. network, natural environment, device and user
characteristics, could be used alongside a set of user-defined
limitation and optimization constraints, to adapt content and thereby
maximize quality of service.
Bazaar: A Middleware for Physical World Abstraction (pp124-145)
K. Fujinami and T. Nakajima
In this paper, we propose a middleware, Bazaar,
for building location and context-aware services without the need to
consider the detail of information capturing, but to allow a developer
to concentrate on his/her main task, i.e. the application logic
development. Bazaar abstracts the physical world by separating
the structures of information and the usage from utilization. It also
serves as a shared ``physical information repository" to maintain
consistency among various applications in the environment, which is
often called the world model. The world model in
Bazaar contains a location model and an artefact model.
The former represents the containment relationship between a unit space
like a house and unit regions like the washroom. The static
specification and dynamically changing status of an artefact is handled
within the artefact model. Here, a sensor augmented artefact acts
as a building block for a smart space. Usually, the artefact has a
primary role and we have a prior understanding of the meaning o the
state-of-use. We call such an artefact a sentient artefact.
This paper describes the design and implementation of Bazaar with
a programming model that reflects the relationship between locations and
objects in the physical environment. Furthermore, we describe
experiences from various application development experiments with
Bazaar.
Listening Comprehension of English
Second Language with Mobil Devices (pp146-165) M. Djoudi The use of the mobile devices in
language learning has been developed at very high speed these last
years. Thus, we are witnessing many research and development projects,
methodologies, and scientific publications. However, the interest in
research related to listening comprehension competence remains
relatively low. In this paper, we propose a simple and original
approach, which aims to use mobile devices for listening comprehension
of foreign language especially English Second Language for French
learners. This
approach is based on an easy to use technology that makes it possible
for learners to work, anywhere and at their own rhythm, the listening
comprehension of a foreign language. With the mobile MP3 player, the
learner can carry a worth of English lessons, practicing pronunciation
and conversation drills with the audio tracks. He can download from web
based mobile-learning environment (named Nomad’s Lang) the MP3 audio
tracks and written lessons (created par teachers) and read them on any
mobile device (PDA, Pocket PC or Laptops, etc.).The paper starts with the summary of
mobile devices, language skills and listening comprehension. It then
highlights our approach of the use of mobile devices for learning
English second language. Finally a learner evaluation is performed. The
paper ends with the discussion of results and conclusion
A Novel Approach for Improving the
Quality of Service for Wireless Video Transcoding (pp167-186) A. M. A.
Ahmad and S.-Y. Lee To deliver streaming video over
wireless networks is an important component for most interactive
multimedia applications running on personal wireless handset devices.
Such personal devices should be inexpensive, compact, and lightweight.
Wireless channels have limited bandwidth and a high channel bit error
rate. Delay variation of packets due to network congestion with the high
bit error rate lessens the quality of video at the handheld device.
Therefore, mobile access to multimedia content requires video
transcoding functionality at the edge of the mobile network for
interworking with heterogeneous networks and services. Under certain
conditions, the bandwidth of a coded video stream needs to be
drastically reduced. We propose a cost-efficient mechanism for improving
the quality of service (QoS) delivered to the mobile user, by
introducing a robust and efficient transcoding scheme as proven by
extensive experiments. The proposed approach refines the motion vectors
value without the need to re-perform the motion estimation process. Then
the transcoding mechanism will be preformed using the new fine motion
vectors. Thus, great amounts of computing resources have been saved.
Exceptional performance is demonstrated in the experiment results, as
these experiments were designed to verify and prove the robustness of
the proposed approach.
