2 research outputs found
Enhanced Multimedia Exchanges over the Internet
Although the Internet was not originally designed for exchanging multimedia streams, consumers heavily depend on it for audiovisual data delivery. The intermittent nature of multimedia traffic, the unguaranteed underlying communication infrastructure, and dynamic user behavior collectively result in the degradation of Quality-of-Service (QoS) and Quality-of-Experience (QoE) perceived by end-users. Consequently, the volume of signalling messages is inevitably increased to compensate for the degradation of the desired service qualities. Improved multimedia services could leverage adaptive streaming as well as blockchain-based solutions to enhance media-rich experiences over the Internet at the cost of increased signalling volume. Many recent studies in the literature provide signalling reduction and blockchain-based methods for authenticated media access over the Internet while utilizing resources quasi-efficiently. To further increase the efficiency of multimedia communications, novel signalling overhead and content access latency reduction solutions are investigated in this dissertation including: (1) the first two research topics utilize steganography to reduce signalling bandwidth utilization while increasing the capacity of the multimedia network; and (2) the third research topic utilizes multimedia content access request management schemes to guarantee throughput values for servicing users, end-devices, and the network. Signalling of multimedia streaming is generated at every layer of the communication protocol stack; At the highest layer, segment requests are generated, and at the lower layers, byte tracking messages are exchanged. Through leveraging steganography, essential signalling information is encoded within multimedia payloads to reduce the amount of resources consumed by non-payload data. The first steganographic solution hides signalling messages within multimedia payloads, thereby freeing intermediate node buffers from queuing non-payload packets. Consequently, source nodes are capable of delivering control information to receiving nodes at no additional network overhead. A utility function is designed to minimize the volume of overhead exchanged while minimizing visual artifacts. Therefore, the proposed scheme is designed to leverage the fidelity of the multimedia stream to reduce the largest amount of control overhead with the lowest negative visual impact. The second steganographic solution enables protocol translation through embedding packet header information within payload data to alternatively utilize lightweight headers. The protocol translator leverages a proposed utility function to enable the maximum number of translations while maintaining QoS and QoE requirements in terms of packet throughput and playback bit-rate. As the number of multimedia users and sources increases, decentralized content access and management over a blockchain-based system is inevitable. Blockchain technologies suffer from large processing latencies; consequently reducing the throughput of a multimedia network. Reducing blockchain-based access latencies is therefore essential to maintaining a decentralized scalable model with seamless functionality and efficient utilization of resources. Adapting blockchains to feeless applications will then port the utility of ledger-based networks to audiovisual applications in a faultless manner. The proposed transaction processing scheme will enable ledger maintainers in sustaining desired throughputs necessary for delivering expected QoS and QoE values for decentralized audiovisual platforms. A block slicing algorithm is designed to ensure that the ledger maintenance strategy is benefiting the operations of the blockchain-based multimedia network. Using the proposed algorithm, the throughput and latency of operations within the multimedia network are then maintained at a desired level
Polymeco : uma ferramenta de análise e comparação de malhas poligonais
Mestrado em Engenharia Electrónica e TelecomunicaçõesOs modelos definidos usando malhas poligonais são usados em diversas
áreas de aplicação para representar diferentes objectos e estruturas.
Dependendo da aplicação, pode ser necessário processar esses modelos, por
exemplo, para diminuir a sua complexidade (simplificação). Este
processamento introduz diferenças, em relação ao modelo original, cuja
avaliação é um passo fundamental para permitir escolher a sequência de
operações e os métodos de processamento que permitam a obtenção de
melhores resultados.
Apesar de algumas ferramentas de análise e comparação das caracterÃsticas
de malhas poligonais serem descritas na literatura, pouca atenção tem sido
prestada à forma como os dados provenientes dessa análise e comparação
podem ser visualizados. Para além disso, devem ser disponibilizadas várias
funcionalidades de forma a permitir uma utilização sistemática destas
ferramentas, assim como uma adequada análise e exploração dos dados
fornecidos.
O PolyMeCo — uma ferramenta de análise e comparação das caracterÃsticas
de malhas poligonais — foi projectado e desenvolvido tendo em conta os
objectivos acima referidos. Através de um ambiente integrado onde diferentes
opções de visualização estão disponÃveis e podem ser usadas de forma
coordenada, o PolyMeCo permite aos utilizadores uma melhor compreensão
dos dados resultantes da aplicação dos números de mérito disponibilizados.
Esta nova ferramenta foi usada com sucesso em dois trabalhos de
investigação: (1) para comparar as caracterÃsticas das malhas resultantes de
dois algoritmos de simplificação de malhas poligonais, e (2) para testar a
aplicabilidade dos números de mérito que disponibiliza como estimadores da
qualidade de modelos poligonais, tal como percebida pelos utilizadores.
ABSTRACT: Polygonal meshes are used in several application areas to model different
objects and structures. Depending on the application, such models sometimes
have to be processed to, for instance, reduce their complexity (mesh
simplification). Such processing introduces error, whose evaluation is of
paramount importance when choosing the sequence of operations that is to be
applied for a particular purpose.
Although some mesh analysis and comparison tools are described in the
literature, little attention has been given to the way mesh features (analysis)
and mesh comparison results can be visualized. Moreover, particular
functionalities have to be made available by such tools, to enable systematic
use and proper data analysis and exploration.
PolyMeCo — a tool for polygonal mesh analysis and comparison — was
designed and developed taking the above objectives into account. It enhances
the way users perform mesh analysis and comparison, by providing an
integrated environment where various mesh quality measures and several
visualization options are available and can be used in a coordinated way, thus
leading to greater insight into the visualized data.
This new tool has been successfully applied in two research works: (1) to
compare between mesh simplification algorithms, and (2) to study the
applicability of the provided computational measures as estimators of user
perceived quality as obtained through an observer study