This dissertation was motivated by the exponential growth in bandwidth capacity of the Internet, coupled with the immense growth of broadband adoption by the public. This has led to the development of a wide variety of new online services. Chief amongst the emerging applications is the delivery of multimedia contents to the end users via the network on-demand. It is the “on-demand” aspect that has led to problems which, despite the advances in hardware technology and network capacity, have hampered wide scale adoption of multimedia delivery. The focus of this dissertation was to address these problems, namely: scalability, cost-effectiveness, and network quality of service for timely presentation of multimedia contents. We proposed an architecture, which we referred to as “Delayed-Multicast”, to address the scalability problem. The new architecture introduced buffers within the network to reduce demands on core network bandwidth and server load. A feasibility study of the architecture was conducted through the use of a prototype. It was found that such a system is within reach by demonstrating the prototype using cheap, common-of-the-shelf (COTS) components, and with help of freely available system software such Linux with real-time support. The introduction of buffers within the network led to the requirement of how to minimize buffer space. We developed an optimal algorithm for allocating buffer space in a single level caching layout (i.e. only one buffer in the transmission path from the server to the end user). For the case of multi-levels network caching, we thoroughly examined different optimization problems from an algorithmic perspective. These problems included how to minimize total system memory, and minimize the maximum memory used per node. We proved that determining the optimal buffer allocation in many of these iv v cases is an NP-complete problem. Consequently, we developed heuristics to handle multi-level caching and showed through simulations that the heuristics greatly help in minimizing buffer space and network bandwidth requirement. An important aspect of the heuristics was how to handle the case when the arrival times of client requests were not known a priori. For these “online” problems we also proposed heuristics that can significantly reduce overall system resource requirements. If the cost of buffer space was also taken into account along with the cost of network bandwidth, a different optimization problem was how to minimize the total system cost. Here, we also proposed heuristics, which in simulations show that the total system cost can be significantly reduced. Besides the problems associated with resource allocation, in terms of buffer space and bandwidth, we also examined the problem of how to provision the necessary network quality of service on-demand. Most current networks rely on best-effort delivery which is ill suited for the delivery of multimedia traffic. We proposed a solution which relied on the use of a programmable network plane, that is present in many current routers, to dynamically alter the priority of flows within the network in real-time. We also demonstrated the effectiveness of the flow prioritization on an actual Nortel router. Finally, we examined the problem of how to admit and achieve fair bandwidth allocation for the end-users within a Differentiated Service (DiffServ) network. Diff- Serv is an IETF standard that aims to provide a “better than best-effort” network in a scalable manner, and is used widely, especially within the same autonomous domain for prioritization different classes of traffic. However, there are open problems on how to provide fair bandwidth allocation amongst competing flows. We proposed an edge-aware resource discovery loop, which as the name suggests, sent packets to gather information about the internal states of the core network. With this information, we proposed a price-based admission control algorithm for use within the DiffServ network that would allow fair admission, effective congestion control, and fair bandwidth allocation amongst different traffic flows.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: MPEG; video; sensor. Includes bibliographical references (p.61-64).

La performance des unités de calcul séquentiel a atteint des limites technologiques qui ont conduit à une transition de la tendance à l'accélération des calculs séquentiels vers une augmentation exponentielle du nombre d'unités de calcul par microprocesseur. Ces nouvelles architectures ne permettent d'augmenter la vitesse de calcul que proportionnellement au parallélisme qui peut être exploité, soit via le modèle de programmation soit par un compilateur optimiseur. Cependant, la disponibilité du parallélisme en soi ne suffit pas à améliorer les performances si un grand nombre de processeurs sont en compétition pour l'accès à la mémoire. Le modèle de streaming répond à ce problème et représente une solution viable pour l'exploitation des architectures à venir. Cette thèse aborde le streaming comme un modèle général de programmation parallèle, plutôt qu'un modèle dédié à une classe d'applications, en fournissant une extension pour le streaming à un langage standard pour la programmation parallèle avec mémoire partagée, OpenMP. Un nouveau modèle formel est développé, dans une première partie, pour étudier les propriétés des programmes qui font appel au streaming, sans les restrictions qui sont généralement associées aux modèles de flot de données. Ce modèle permet de prouver que ces programmes sont déterministes à la fois fonctionnellement et par rapport aux deadlocks, ce qui est essentiel pour la productivité des programmeurs. La deuxième partie de ce travail est consacrée à l'exploitation efficace de ce modèle, avec support logiciel à l'exécution et optimisations de compilation, à travers l'implantation d'un prototype dans le compilateur GCC.

<p>This thesis covers the investigation of different content sources on the Internet and the analysis of the requirements they put on a set-top box. It also covers the adaptation of the set-top box to one of these sources. </p><p>An IP based set-top box (IP-STB) is mainly constructed for access to TV and video distributed over a high speed network. The IP-STB is also connected to the Internet and it potentially has access to all of the Internet based content. This could provide the user of the IP-STB with a lot of new services and was the stating point for my thesis work.</p><p>The goal of this thesis was to make a broad investigation of different content sources on the Internet and to adapt an IP-STB to one of them. </p><p>The investigation focused on streaming media content and how it was distributed over the Internet. It resulted in a representative overview of the streaming media content available and how the content is distributed. The IP-STB was adapted to handle the Streaming HTTP protocol which made it possible to listen to web radio transmissions from Sveriges Radio and other providers using the same protocol for their distribution.</p>

<p>The trends in todays tele- and datacommunication market point toward using IP for all sorts of service delivery ranging from voice calls to TV. The next natural step in this evolution is to provide the same set of services to the end users independent of the access technology and device used. The IP Multimedia Subsystem (IMS) is an IP based telecommunications platform which targets this and lets the operators develop new services once which can then be used on many different devices.</p><p>This thesis examines the integration of IPTV and IMS. Can IMS be used to deliver TV services and can the IPTV set-top-boxes of today be used as clients in IMS? Since this is a new and previously unexamined area an explorative approach is taken. The aim is to identify how such an integration could be performed and the possible problems which have to be solved. To assist in this exploration a TV-push service based on IMS technology is constructed.</p><p>Based on the experiences from this service a general architecture for IPTV in IMS is suggested.</p><p>A number of problems crucial to solve for a successful integration are identified and possible solutions to these are discussed.</p>

Mobile devices are becoming more prevalent and complex. As a result, the wireless communication aspect of these devices is becoming increasingly significant. At the same time, video demands in terms of availability and quality are also on the uprise. High definition (HD) video is the standard of choice for meeting today's video demands. However, HD video is characterized by high data rates. Therefore, there is heightened interest in the 60-GHz spectrum as it is suitable for streaming uncompressed HD video. On the other hand, 802.11 wireless technology, compared to 60-GHz, is much more established and widely available and able to cater to a wide variety of devices. HD video compressed using H.264 can be wirelessly streamed via 802.11 wireless networks. However, such wireless networks are prone to packet losses, which result in degraded perceptual quality of video. It is thus important to perform error concealment in order to improve the visual quality of degraded video. Among the key techniques in performing error concealment on video compressed with H.264 is spatial motion vector recovery. This paper proposes a new spatial motion vector recovery technique (MI-WAM) that takes advantage of properly decoded motion vectors. MI-WAM and pre-existing MV recovery techniques are used to provide different corresponding macroblock candidates that compete for the best concealment of each lost macroblock in what will be referred to as competitive motion vector recovery (CMVR). / Graduation date: 2012

Collection understanding shifts the traditional focus of retrieval in large collections from locating specific artifacts to gaining a comprehensive view of the collection. Visualization tools are critical to the process of efficient collection understanding. By presenting simple visual interfaces and intuitive methods of interacting with a collection, users come to understand the essence of the collection by focusing on the artifacts. This thesis discusses a practical approach for enhancing collection understanding in image collections.

The Internet has rapidly evolved from being a scientific experiment to a commercial network connecting millions of hosts that carries traffic generated by a large amount of applications with diverse requirements. Its architecture was however designed to enable efficient point-to-point delivery of bulk data, and can not provide statistical guarantees on the timely delivery of delay sensitive data such as streaming and real-time multimedia. Thus, applications that require low loss probabilities in today's Internet have to use some end-to-end error recovery mechanism. For delay sensitive applications the introduced latency by the applied schemes has to be low as well. Traffic control functions such as delay limited shaping and forward error correction (FEC), and multiple description coding (MDC) have been proposed for variable bitrate video. Their major drawback is, however, that it is difficult to predict their efficiency, as it depends on many factors like the characteristics of the stream itself, the characteristics of the traffic in the network and the network parameters. Consequently, it is difficult to decide which control mechanisms to employ, how to combine them and to choose the right parameters (e.g. block length, code rate) for optimal performance. In this thesis we present results on the efficiency of traffic control functions and MDC for video transmission based on mathematical models and simulations. We investigate the efficiency of delay limited traffic shaping and the trade-offs in the joint use of traffic shaping and forward error correction. We identify the packet size distribution of the traffic in the network as an additional factor that may influence the efficiency of FEC, and present a thorough analysis of its possible effects. We present an analytical comparison of MDC versus media-dependent FEC and media-independent FEC, and based on the results we conclude that MDC is a promising error control solution for multimedia communications with very strict delay bounds in an environment with bursty losses. We combine the analytical results with traces from measurements performed on the Internet to evaluate how efficient these error control schemes are under real loss patterns. We compare the efficiency of MDC and media-dependent FEC in the presence of channel estimation errors; we propose a new rate allocation method, which is robust to mis-estimations of the channel state and which improves error resilience on non-stationary channels. Finally we present an analytical model of the performance of an end-point-based multimedia streaming architecture based on multiple distribution trees and forward error correction, and analyze the behavior of the architecture for a large number of nodes. / QC 20101115

Driven by the increasing capacity of integrated circuits, multiprocessorsystems-on-chip (MPSoCs) are widely used in modern consumer electron-ics devices. In this thesis, the performance analysis and implementationmethodologies are explored to design predictable streaming applications onMPSoCs computing platforms. The application functionality and concur-rency are described in synchronous data flow (SDF) computational models,and two state-of-the-art architecture templates are adopted as multiproces-sor architectures, i.e., network-on-chip (NoC) based MPSoC and hybrid re-configurable CPU/FPGA platforms. Based on the author’s contributions onsimulation and formal analytical methods, performance analysis and designspace exploration for embedded MPSoCs architectures have been addressed. An energy efficient design space exploration flow is proposed for stream-ing applications with guaranteed throughput on NoC based MPSoCs, in whichboth application throughput analysis and system energy calculation are car-ried out by simulation on a multi-clocked synchronous modelling frame-work. On the other hand, based on event models of data streams, a formalanalytical scheduling framework for real-time streaming applications withminimal buffer requirement on hybrid CPU/FPGA architectures is exploited.The scheduling problem has been formalized declaratively by constraint basetechniques, and solved by a public domain constraint solver. Consecutively,the constraint based method has been extended to solve problems rangingfrom global computation/communication scheduling and reconfiguration anal-ysis to Pareto efficient design. Finally, a prototype of stream processing sys-tem on FPGA based MPSoC is built to substantiate the results from theoreti-cal studies in this thesis. / QC 20101207 / SysModel / Andres

The transmitting of video content over Vehicular Ad Hoc Networks (VANETs) faces a great number of challenges caused by strict QoS (Quality of Service) requirements and highly dynamic network topology. In order to tackle these challenges, multipath forwarding schemes can be regarded as potential solutions. However, route coupling effect and the path length growth severely impair the performance of multipath schemes. In this thesis, the current research status about video streaming over VANETs as well as multipath transmissions are reviewed. With the demand to discover a more suitable solution, we propose the Location-Aware Multipath Video Streaming (LIAITHON+) protocol to address video streaming over urban VANETs. LIAITHON+ uses location information to discover relatively short paths with minimal route coupling effect. The performance results have shown it outperforms the underlying single path solution as well as the node-disjoint multipath solution. In addition, the impact of added redundancy on the multipath solution is investigated through LIAITHON+. According to the results, added redundancy has a different impact depending on the data rate.