122,555 research outputs found
MULTIMEDIA ON GEOGRAPHIC NETWORK
In this thesis we investigate the topic of the multimedia contents distribution on a geo-
graphic network which is a rarefied and huge field. First of all we have to classify the main
parts necessary in the multimedia distribution on a geographic network. The main aspects
of a geographic network that will be highlighted in this thesis are: the mechanism used to
retrieve the sources of the multimedia content; in the case of the peer-to-peer network on
geographic network one of the most important mechanism is the query flooding protocol.
The kind of overlay network (peer-to-peer) used to distribute the multimedia content. The
usage of this overlay network in a multicast network. The security of the overlay network
over a geographic network.
Therefore the first topic which is investigated in this thesis is the query flooding protocol
that can be used in any kind of query operation on a peer-to-peer network. For this protocol
we achieve an analytical model through a complex analysis of the proxies network. In this
analysis we can see how the proxies permit an improvement in the performance with respect
to the routing operations in a generic network of routers. Moreover we address a simple
formulation and framework about the performance of the network with and without layer
7 (proxy) and we apply them in three different types of scenarios to show the advantages
achieved with the usage of proxies instead of routers.
Through the query flooding operation, each peer of the peer-to-peer network can achieve
the list of the peers that hold the desired multimedia content. In a multimedia content dis-
tribution system, after the previous step in which the list of the peers that hold the desired multimedia content is retrieved, it is necessary to establish the kind of peer-to-peer network
used to distribute this multimedia content to the peers that require it. Therefore the second
aspect analysed in this thesis, is how the peer-to-peer network is built so that it is possible to
provide the multimedia content to the vast majority of peers (that require this content) with
the minimum delay. The construction of the peer-to-peer networks used for the distribution
of the multimedia contents is not a very investigated field. Thus in this thesis we produce
new algorithms used to build peer-to-peer networks in an incremental way on asymmetric
and radio channel and we establish which algorithm is better with respect to the maximum
delay of the network, the maximization of the number of peers accepted in the network and
the minimization of the bit error probability of each peer of the peer-to-peer network.
In this thesis, we propose an usage of the overlay network (peer-to-peer network) in
a multicast network. We introduce an innovative mechanism that exploits the peer-to-peer
network to make reliable a standard unreliable multicast network. Moreover we present an
analytical model for this innovative mechanism.
Finally the last aspect of a geographic network is the security of the communications
among a group of peers. Thus to ensure the maximum level of security with secure commu-
nications among a group of three or more peers, in this thesis we propose a new protocol,
based on the Massey Omura protocol, which can allow the communications among the
peers of a peer-to-peer network in a secure way. Moreover we present the security prob-
lems of this Massey Omura Multiple Users Protocol and how it is possible to avoid these
issues through a specific encryption function and a specific decryption function by chang-
ing the encryption and decryption keys of each peer when the source peer changes. Finally
we present a new cryptography protocol which we use to share the decryption shared key
that is used in the Massey Omura Multiple Users Protocol
The relationship between IR and multimedia databases
Modern extensible database systems support multimedia data through ADTs. However, because of the problems with multimedia query formulation, this support is not sufficient.\ud
\ud
Multimedia querying requires an iterative search process involving many different representations of the objects in the database. The support that is needed is very similar to the processes in information retrieval.\ud
\ud
Based on this observation, we develop the miRRor architecture for multimedia query processing. We design a layered framework based on information retrieval techniques, to provide a usable query interface to the multimedia database.\ud
\ud
First, we introduce a concept layer to enable reasoning over low-level concepts in the database.\ud
\ud
Second, we add an evidential reasoning layer as an intermediate between the user and the concept layer.\ud
\ud
Third, we add the functionality to process the users' relevance feedback.\ud
\ud
We then adapt the inference network model from text retrieval to an evidential reasoning model for multimedia query processing.\ud
\ud
We conclude with an outline for implementation of miRRor on top of the Monet extensible database system
CHORUS Deliverable 2.2: Second report - identification of multi-disciplinary key issues for gap analysis toward EU multimedia search engines roadmap
After addressing the state-of-the-art during the first year of Chorus and establishing the existing landscape in
multimedia search engines, we have identified and analyzed gaps within European research effort during our second year.
In this period we focused on three directions, notably technological issues, user-centred issues and use-cases and socio-
economic and legal aspects. These were assessed by two central studies: firstly, a concerted vision of functional breakdown
of generic multimedia search engine, and secondly, a representative use-cases descriptions with the related discussion on
requirement for technological challenges. Both studies have been carried out in cooperation and consultation with the
community at large through EC concertation meetings (multimedia search engines cluster), several meetings with our
Think-Tank, presentations in international conferences, and surveys addressed to EU projects coordinators as well as
National initiatives coordinators. Based on the obtained feedback we identified two types of gaps, namely core
technological gaps that involve research challenges, and âenablersâ, which are not necessarily technical research
challenges, but have impact on innovation progress. New socio-economic trends are presented as well as emerging legal
challenges
Advanced content-based semantic scene analysis and information retrieval: the SCHEMA project
The aim of the SCHEMA Network of Excellence is to bring together a critical mass of universities, research centers, industrial partners and end users, in order to design a reference system for content-based semantic scene analysis, interpretation and understanding. Relevant research areas include: content-based multimedia analysis and automatic annotation of semantic multimedia content, combined textual and multimedia information retrieval, semantic -web, MPEG-7 and MPEG-21 standards, user interfaces and human factors. In this paper, recent advances in content-based analysis, indexing and retrieval of digital media within the SCHEMA Network are presented. These advances will be integrated in the SCHEMA module-based, expandable reference system
Strategies for Searching Video Content with Text Queries or Video Examples
The large number of user-generated videos uploaded on to the Internet
everyday has led to many commercial video search engines, which mainly rely on
text metadata for search. However, metadata is often lacking for user-generated
videos, thus these videos are unsearchable by current search engines.
Therefore, content-based video retrieval (CBVR) tackles this metadata-scarcity
problem by directly analyzing the visual and audio streams of each video. CBVR
encompasses multiple research topics, including low-level feature design,
feature fusion, semantic detector training and video search/reranking. We
present novel strategies in these topics to enhance CBVR in both accuracy and
speed under different query inputs, including pure textual queries and query by
video examples. Our proposed strategies have been incorporated into our
submission for the TRECVID 2014 Multimedia Event Detection evaluation, where
our system outperformed other submissions in both text queries and video
example queries, thus demonstrating the effectiveness of our proposed
approaches
Using the Internet to improve university education: Problem-oriented web-based learning and the MUNICS environment
Up to this point, university education has largely remained unaffected by the developments of novel approaches to web-based learning. The paper presents a principled approach to the design of problem-oriented, web-based learning at the university level. The principles include providing authentic contexts with multimedia, supporting collaborative knowledge construction, making thinking visible with dynamic visualisation, quick access to content resources via Information and Communication Technologies (ICT), and flexible support by tele-tutoring. These principles are used in the Munich Net-based Learning In Computer Science (MUNICS) learning environment, which is designed to support students of computer science to apply their factual knowledge from the lectures to complex real-world problems. For example, students can model the knowledge management in an educational organisation with a graphical simulation tool. Some more general findings from a formative evaluation study with the MUNICS prototype are reported and discussed. E.g., the students' ignorance of the additional content resources is discussed in the light of the well-known finding of insufficient use of help systems in software applicationsBislang wurden neuere AnsĂ€tze zum web-basierten Lernen in nur geringem MaĂe zur Verbesserung des UniversitĂ€tsstudiums genutzt. Es werden theoretisch begrĂŒndete Prinzipien fĂŒr die Gestaltung problemorientierter, web-basierter Lernumgebungen an der UniversitĂ€t formuliert. Zu diesen Prinzipien gehören die Nutzung von Multimedia-Technologien fĂŒr die Realisierung authentischer Problemkontexte, die UnterstĂŒtzung der gemeinsamen Wissenskonstruktion, die dynamische Visualisierung, der schnelle Zugang zu weiterfĂŒhrenden Wissensressourcen mit Hilfe von Informations- und Kommunikationstechnologien sowie die flexible UnterstĂŒtzung durch Teletutoring. Diese Prinzipien wurden bei der Gestaltung der MUNICS Lernumgebung umgesetzt. MUNICS soll Studierende der Informatik bei der Wissensanwendung im Kontext komplexer praktischer Problemstellungen unterstĂŒtzen. So können die Studierenden u.a. das Wissensmanagement in einer Bildungsorganisation mit Hilfe eines graphischen Simulationswerkzeugs modellieren. Es werden Ergebnisse einer formativen Evaluationsstudie berichtet und diskutiert. Beispielsweise wird die in der Studie festgestellte Ignoranz der Studierenden gegenĂŒber den weiterfĂŒhrenden Wissensressourcen vor dem Hintergrund des hĂ€ufig berichteten Befunds der unzureichenden Nutzung von Hilfesystemen beleuchte
- âŠ