One aim of this thesis is to provide an overview of technological, economic and legal aspects of the distribution of audiovisual content over internet and other IP networks. This thesis will provide introduction to most widely used compression methods of digital audio and video, transmission methods and protocols. Another aim is to create a case study that deals with selecting the best solution for a commercial project of Video On Demand server. This objective is achieved by applying methods of multi-criteria evaluation of options based on theoretical analysis of distribution solutions. The secondary aim is to determine the total cost of ownership of the different options by using the methodology of TCO (Total Cost of ownership). This thesis also provides a comparison with the solution based on purely non-commercial focus.

Small-amplitude, high-frequency (ultrasound) forcing of fluid/particle systems is being used in a number of applications associated with non-destructive fluid mixing and the movement/manipulation of particles in suspension. Of most importance in this context are the second-order, steady, effects arising from the nonlinear interaction of a leading-order oscillatory field with itself. In this thesis we consider some of these steady effects in both incompressible and compressible fluids. We first consider the axisymmetric steady streaming generated in an incompressible, viscous fluid contained between two (radially) infinite parallel plates, each oscillating in a direction normal to its own plane. In the limit of small-amplitude, high-frequency oscillations, we show that the steady-streaming flow in the fluid bulk is driven by thin streaming sublayers at the plates, at which the normal velocity is zero and the radial velocity varies linearly with distance from the axis of rotational symmetry. Effectively, in the bulk flow, the bounding plates appear as (no-slip) impermeable walls that stretch radially. This bulk-flow problem is extended to allow for the analogous steady flow of two immiscible, incompressible, viscous fluids, each undergoing a radial-stretching motion appropriate to high-frequency steady streaming. For a flat interface between the fluids, a self-similar solution reduces the Navier--Stokes equations to a nonlinear boundary-value problem, the solution of which exhibits an interesting structure in the limit of large Reynolds number. In this limit, solutions can be found using matched asymptotic expansions, but the location of the interface between the fluids can only be determined if terms that are exponentially small in the Reynolds number are included. It is shown that for fluids of almost-equal densities, exponentially-small differences can have a leading-order effect on the observed flow. The second part of the thesis is concerned with the (steady) acoustic radiation force on a rigid sphere submerged in a compressible, inviscid fluid, when the wavelength of the incident acoustic field is large compared to the radius of the sphere. In this limit, a matched asymptotic expansion method is used to derive an expression for the acoustic radiation force, on both fixed and free rigid spheres, due to a range of incident fields. For incident acoustic fields that are appropriate to planar and circular waveguides/channels, expressions are derived for the scattered field and the radiation force on a rigid sphere in the long-wavelength limit. Fixed and free spheres located both on and off the axis of symmetry of these incident fields are considered. This is an extension to the current literature, in which numerical methods are used to examine the scattering from spheres in an off-axis position, and problems are restricted to the consideration of fixed spheres only. It is shown that there are stable and unstable positions within the waveguide where any off-axis acoustic radiation force vanishes, leaving only an along-channel component. For free spheres, these positions are shown to be dependent on the relative particle density and it is suggested that this may allow for a mechanism to sort such small particles radially in a circular waveguide, if secondary scattering effects are neglected.

One of the main challenges in delivering content over the Internet today is the absence of a centralized monitoring and control system [38]. Software Defined Networking has paved the way to provide a much needed control over network traffic. OpenFlow is now being standardized as part of the Open Networking Foundation, and Software Defined Exchanges (SDXes) provide a framework to use OpenFlow for multi-domain routing. Prototype deployments of Software Defined Exchanges have recently come into existence as a platform for Future Internet Architecture to eliminate the need for core routing technology used in today’s Internet. In this work, we look at how application delivery, in particular, Dynamic Adaptive Streaming over HTTP (DASH) and Nowcasting take advantage of a Software Defined Exchange. We compare unsophisticated controllers to more sophisticated ones which we call a ”load balancer” and find that implementing a good controller for inter-domain routing can result in better network utilization and application performance. We then design, develop and evaluate a prototype for a Content Distribution Network (CDN) that uses resources at SDXes to provide higher quality bitrates for a DASH client.

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第23541号 / 情博第771号 / 新制||情||132(附属図書館) / 京都大学大学院情報学研究科知能情報学専攻 / (主査)教授 河原 達也, 教授 黒橋 禎夫, 教授 森 信介 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

Triangle counting is a major graph problem with several applications in social network analysis, anomaly detection, etc. A considerable amount of work has contributed to approximately computing the global triangle counts using several computational models. One of the most popular streaming models considered is Edge Streaming in which the edges arrive in the form of a graph stream. We categorize the existing literature into two categories: Fixed Memory (FM) approach, and Fixed Probability (FP) approach. As the size of the graphs grows, several challenges arise such as memory space limitations, and prohibitively long running time. Therefore, both FM and FP categories exhibit some limitations. FP algorithms fail to scale for massive graphs. We identified a limitation of FM category $i.e.$ FM algorithms have higher computational time than their FP variants. In this work, we present a new category called the Hybrid approach that overcomes the limitations of both FM and FP approaches. We present two new algorithms that belong to the hybrid category: Neighbourhood Hybrid Multisampling (NHMS) and Triest/ThinkD Hybrid Sampling (THS) for estimating the number of global triangles in graphs. These algorithms are highly scalable and have better running time than FM and FP variants. We experimentally show that both NHMS and THS outperform state-of-the-art algorithms in space-efficient environments. / Graduate

Social media is the undisputed leader regarding video streaming consumption at an international level, to the detriment of SVOD services. We arrived at this observation trying to understand consumer behaviors regarding this phenomenon. Surprised by this, we sought to understand what motivates consumers to watch streaming video. In the literature, scholars seeking to study the motivations and satisfactions (called gratification factors) of consumers in media use are working with the Uses and Gratification Theory. However, while this theory explains the use of a medium, it does not explain the preference of one medium over another. We therefore wanted to use the Uses and Gratifications framework to make this comparison between social media and SVOD, and thus find an explanation for our observation: the superiority of social media. We drew on previous work to construct gratification factors applicable to SVOD, social media and video streaming. To confirm the reliability and validity of these constructs, we conducted a factorial analysis in a quantitative study, using a questionnaire distributed to the French population. Moreover, we used the data from this survey to build explanatory models for the use of social media and SVOD. Therefore, our study shows that the Uses and Gratifications Theory can be used to explain consumers’ preference for social media over SVOD services, by highlighting that the gratification factors which are the most decisive are content, process and social. Moreover, the formation of our constructs (content, social, process and technology gratifications) is the result of our reorganization of the gratifications already considered in the existing literature so that they correspond most accurately to the current behaviors of streaming video consumers. We thus provide a new basic model of analysis, which could be used by other studies on video streaming. From a practical point of view, our study also allows us to suggest to video streaming companies the points on which they can work to meet consumers’ expectations: that is to say on the possibility for users to adapt their consumption to their available time and on the possibility for interactivity directly on the platforms.

Sampling is considered to be a core component of data analysis making it possibleto provide a synopsis of possibly large amounts of data by maintainingonly subsets or multisubsets of it. In the context of data streaming, an emergingprocessing paradigm where data is assumed to be unbounded, samplingoffers great potential since it can establish a representative bounded view ofinfinite data streams to any streaming operations. This further unlocks severalbenefits such as sustainable continuous execution on managed memory, trendsensitivity control and adaptive processing tailored to the operations that consumedata streams.The main aim of this thesis is to conduct an experimental study in order tocategorize existing sampling techniques over a selection of properties derivedfrom common streaming use cases. For that purpose we designed and implementeda testing framework that allows for configurable sampling policiesunder different processing scenarios along with a library of different samplersimplemented as operators. We build on Apache Flink, a distributed streamprocessing system to provide this testbed and all component implementationsof this study. Furthermore, we show in our experimental analysis that there isno optimal sampling technique for all operations. Instead, there are differentdemands across usage scenarios such as online aggregations and incrementalmachine learning. In principle, we show that each sampling policy trades offbias, sensitivity and concept drift adaptation, properties that can be potentiallypredefined by different operators.We believe that this study serves as the starting point towards automatedadaptive sampling selection for sustainable continuous analytics pipelines thatcan react to stream changes and thus offer the right data needed at each time,for any possible operation

Adaptive streaming approaches over Hypertext Transfer Protocol (HTTP), such as Apple's HTTP Live streaming (HLS) and Microsoft's Live Smooth Streaming, have recently become very popular. This master's thesis project developed and evaluated several media rate adaptation algorithms optimized for mobile networks with a client running on Google's Android operating system. The deployed service supports HLS and the emerging ISO/IEC MPEG standard called Dynamic Adaptive Streaming over HTTP (MPEG-DASH). Live media was the focus of the evaluation, since this content can not be cached in advance at the user's device, hence the quality of the user's experience will be affected by the currently available bandwidth which the user can utilize. Experiments were performed for multiples scenarios illustrating different network capabilities, especially various amounts of bandwidth available to the user. This project has produced an implementation of HTTP-based adaptive streaming. This implementation follows the MPEG standard and enables robust and smooth playback of live video content via Google's Android devices. Results of the experiments have shown that the proposed adaptation mechanisms efficiently utilize the available bandwidth of the network. A clear conclusion of this thesis is that adaptive streaming will in fact enable substantial numbers of users to enjoy live media streaming to their devices / Adaptiv strömnings metoder över Hypertext Transfer Protocol (HTTP), till exempel Apples HTTP Live streaming (HLS) och Microsoft Live Smooth Streaming, har nyligen blivit mycket populära. Detta examensarbete utvecklas och utvärderar flera medier algoritmer anpassning av överföringshastigheten optimerad för mobila nätverk med en klient som körs på Googles Android-operativsystem. Systemet kommer att överväga HLS och den framväxande ISO/IECMPEG-standarden som kallas Dynamisk Adaptiv Strömmande över HTTP (MPEG-DASH). Direktsänd media var i fokus för utvärderingen, eftersom detta innehåll inte kan cachas i förväg på användarens enhet, därmed kvaliteten på användarens upplevelse kommer att påverkas av den aktuella tillgängliga bandbredden som användaren kan utnyttja. Experimenten utfördes för flera scenarier och illustrerar olika nätverksfunktioner, särskilt hur olika mängder bandbredd är tillgänglig för användaren. Detta projekt har producerat ett genomförande av HTTP-baserade adaptiva strömning. Denna implementering följer MPEG-standarden och möjliggör robusta och smidig uppspelning av direktsänd video innehåll via Googles Android-enheter. Resultat av experiment har visat att den föreslagna anpassningsmekanismerna effektiva sätt att utnyttja den tillgängliga bandbredden i nätverket. En tydlig slutsats i denna avhandling är att adaptive strömning faktiskt kommer att möjliggöra ett stort antal användare att njuta av direktsänd medieströmning till sina enheter.

The ever increasing demand for video content directed the focus of researchfrom traditional server-based schemes to peer-to-peer systems for videodelivery. In such systems, video data is delivered to the users by utilizing theresources of the users themselves, leading to a potentially scalable solution.Users connect to each other, forming a p2p overlay network on top of theInternet and exchange the video segments among themselves. The performanceof a p2p system is characterized by its capability to deliver the videocontent to all peers without errors and with the smallest possible delay. Thisconstitutes a challenge since peers dynamically join and leave the overlay andalso contribute different amounts of resources to the system.The contribution of this thesis lies in two areas. The first area is theperformance evaluation of the most prominent p2p streaming architectures.We study the streaming quality in multiple-tree-based systems. We derivemodels to evaluate the stability of a multiple tree overlay in dynamic scenariosand the efficiency of the data distribution over the multiple trees. Then, westudy the data propagation in mesh-based overlays. We develop a generalframework for the evaluation of forwarding algorithms in such overlays anduse this framework to evaluate the performance of four different algorithms.The second area of the thesis is a study of streaming in heterogeneous p2poverlays. The streaming quality depends on the aggregate resources that peerscontribute to the system: low average contribution leads to low streamingquality. Therefore, maintaining high streaming quality requires mechanismsthat either prohibit non-contributing peers or encourage contribution. In thisthesis we investigate both approaches. For the former, we derive a model tocapture the evolution of available capacity in an overlay and propose simpleadmission control mechanisms to avoid capacity drainage. For the latter, inour last work, we propose a novel incentive mechanism that maximizes thestreaming quality in an overlay by encouraging highly contributing peers tooffer more of their resources. / QC 20100506

Denna uppsats syftar till att utforska äldres relation till strömningstjänster och designens inverkan på deras användande. Mot en bakgrund av nya lagar gällande offentlig tillgänglighetsanpassning intresserar sig uppsatsen för hur tillgänglighetsanpassningen ser ut i strömningstjänster. Ur ett tillgänglighetsperspektiv undersöks äldres attityder till och problem med strömningstjänster för att för att kunna ge förslag på hur tillgänglighetsarbetet kan förändras eller förbättras. Genom intervjuer framkommer det att en stor del av den problematiken som de äldre upplever inte beror strikt på den grafiska designen, utan problematiken är bredare och berör saker som språkanvändning i tjänsterna, krångliga supportsamtal och en rädsla att göra fel. Som förslag på att åtgärda problemen efterlyses en breddad designroll som utgår från en helhet baserad på sambanden mellan visuella och icke-visuella komponenter för att på så vis verka för att göra digitala tjänster mer tillgängliga för äldre människor i samhället.