Video-On-Demand (VOD) has appeared as an important technology for many multimedia applications such as news on demand, digital libraries, home entertainment, and distance learning. In its simplest form, delivery of a video stream requires a dedicated channel for each video session. This scheme is very expensive and non-scalable. To preserve server bandwidth, many users can share a channel using multicast. Two types of multicast have been considered. In a non-periodic multicast setting, users make video requests to the server; and it serves them according to some scheduling policy. In a periodic broadcast environment, the server does not wait for service requests. It broadcasts a video cyclically, e.g., a new stream of the same video is started every t seconds. Although, this type of approach does not guarantee true VOD, the worst service latency experienced by any client is less than t seconds. A distinct advantage of this approach is that it can serve a very large community of users using minimal server bandwidth. In VOD System it is desirable to provide the user with the video-cassette-recorder-like (VCR) capabilities such as fast-forwarding a video or jumping to a specific frame. This issue in the broadcast framework is addressed, where each video and its interactive version are broadcast repeatedly on the network. Existing techniques rely on data prefetching as the mechanism to provide this functionality. This approach provides limited usability since the prefetching rate cannot keep up with typical fast-forward speeds. In the same environment, end users might have access to different bandwidth capabilities at different times. Current periodic broadcast schemes, do not take advantage of high-bandwidth capabilities, nor do they adapt to the low-bandwidth limitation of the receivers. A heterogeneous technique is presented that can adapt to a range of receiving bandwidth capability. Given a server bandwidth and a range of different client bandwidths, users employing the proposed technique will choose either to use their full reception bandwidth capability and therefore accessing the video at a very short time, or using part or enough reception bandwidth at the expense of a longer access latency.

Peer to Peer (P2P) models are based on user altruism, wherein a user shares its content with other users in the pool and it also has an interest in the content of the other nodes. Most P2P systems in their current form are not fair in terms of the content served by a peer and the service obtained from swarm. Most systems suffer from free rider's problem where many high uplink capacity peers contribute much more than they should while many others get a free ride for downloading the content. This leaves high capacity nodes with very little or no motivation to contribute. Many times such resourceful nodes exit the swarm or don't even participate. The whole scenario is unfavorable and disappointing for P2P networks in general, where participation is a must and a very important feature. As the number of users increases in the swarm, the swarm becomes robust and scalable. Other important issues in the present day P2P system are below optimal Quality of Service (QoS) in terms of download time, end-to-end latency and jitter rate, uplink utilization, excessive cross ISP traffic, security and cheating threats etc. These current day problems in P2P networks serve as a motivation for present work. To this end, we present an efficient data distribution framework in Peer-to-Peer (P2P) networks for media streaming and file sharing domain. The experiments with our model, an alliance based peering scheme for media streaming, show that such a scheme distributes data to the swarm members in a near-optimal way. Alliances are small groups of nodes that share data and other vital information for symbiotic association. We show that alliance formation is a loosely coupled and an effective way to organize the peers and our model maps to a small world network, which form efficient overlay structures and are robust to network perturbations such as churn. We present a comparative simulation based study of our model with CoolStreaming/DONet (a popular model) and present a quantitative performance evaluation. Simulation results show that our model scales well under varying workloads and conditions, delivers near optimal levels of QoS, reduces cross ISP traffic considerably and for most cases, performs at par or even better than Cool-Streaming/DONet. In the next phase of our work, we focussed on BitTorrent P2P model as it the most widely used file sharing protocol. Many studies in academia and industry have shown that though BitTorrent scales very well but is far from optimal in terms of fairness to end users, download time and uplink utilization. Furthermore, random peering and data distribution in such model lead to suboptimal performance. Lately, new breed of BitTorrent clients like BitTyrant have shown successful strategic attacks against BitTorrent. Strategic peers configure the BitTorrent client software such that for very less or no contribution, they can obtain good download speeds. Such strategic nodes exploit the altruism in the swarm and consume resources at the expense of other honest nodes and create an unfair swarm. More unfairness is generated in the swarm with the presence of heterogeneous bandwidth nodes. We investigate and propose a new token-based anti-strategic policy that could be used in BitTorrent to minimize the free-riding by strategic clients. We also proposed other policies against strategic attacks that include using a smart tracker that denies the request of strategic clients for peer listmultiple times, and black listing the non-behaving nodes that do not follow the protocol policies. These policies help to stop the strategic behavior of peers to a large extent and improve overall system performance. We also quantify and validate the benefits of using bandwidth peer matching policy. Our simulations results show that with the above proposed changes, uplink utilization and mean download time in BitTorrent network improves considerably. It leaves strategic clients with little or no incentive to behave greedily. This reduces free riding and creates fairer swarm with very little computational overhead. Finally, we show that our model is self healing model where user behavior changes from selfish to altruistic in the presence of the aforementioned policies.

The presence of millions of interconnected personal computing devices has given rise to a new class of decentralized networking applications, which are loosely labeled as peer-to-peer (P2P) applications. These P2P applications leverage resources such as processing cycles, storage, content, and network bandwidth available to the user devices, which are also known as peers. A number of current systems - SETI@home, Napster, BitTorrent, and Pastry - are examples of these emerging P2P systems. To fully realize the potential of the peer-to-peer technology, there is a need to define and provide a set of core competencies, serving as the basic services upon which various peer-to-peer applications can be built on. Among these core competencies, this dissertation focuses on two fundamental services, which are search and delivery. In the first part of the dissertation, delivery techniques to support video-on-demand services in wireline and wireless P2P networks are investigated. Video services are considered due to two reasons. First, video services are the pivotal basis for many other multimedia applications. Second, it is challenging to provide on-demand video services due to asynchronous playback progresses at peers. The proposed techniques enable efficient video sharing between peers with asynchronous playback progresses, and maximize peer bandwidth utilization. In the second part of the dissertation, the problem of supporting continuous moving range queries in wireless mobile peer-to-peer networks is studied. Continuous moving range queries have a number of applications when a moving object wants to monitor its surrounding environment for a period of time. When a fixed network infrastructure is not available, wireless mobile peer-to-peer networks become a viable option to support the continuous query system. The proposed distributed solution ensures the accuracy of the query results under realistic assumptions, and incurs much less overhead than alternative solutions.

During the last 15 years, the film industry has undergone severe technological, cultural, and economic transformations initiated through online film distribution. Existing players need to adapt and innovate their business models to stay competitive. However, there is little knowledge about what players actually do in this respect. Since the film industry is of great economic and cultural importance, it is essential for researchers and managers alike to understand the transformations in the business models of film companies. Therefore, this thesis aims to investigate which areas of the business models of Nordic film studios have been most affected by changes and how the studios have responded to these transformations. Based on a longitudinal, comparative case study of the companies SF Studios and Nordisk Film, the study reveals that distribution channels, revenue streams, margins, partner network, customer needs, and core offerings have changed the most. The main transformations can be seen in stronger partnerships and an increased focus on in-house production to serve the high demand for content, secure a content flow for distribution, and generate new revenues. / Under de senaste 15 åren har filmindustrin genomgått stora tekniska, kulturella och ekonomiska förändringar som inleddes av den digitala filmdistributionens uppkomst. För att förbli konkurrenskraftiga måste nuvarande aktörer anpassa och förnya sina affärsmodeller. Det finns dock lite kunskap om vad företagen faktiskt gör i detta avseende. Eftersom filmindustrin har ett stort ekonomiskt och kulturellt värde är det avgörande att förstå förändringar i filmbolagens affärsmodeller, både för forskare och ledare. Syftet med denna uppsats är därför att undersöka vilka delar av nordiska filmstudiors affärsmodeller som är mest drabbade av förändringar och hur studiorna har reagerat på detta. Baserat på en longitudinell, jämförande fallstudie av företagen SF Studios och Nordisk Film visar denna studie att distributionskanaler, intäkter, marginaler, partnernätverk, kundbehov och kärnutbud har förändrats mest. De huvudsakliga förändringarna visas i starkare partnerskap och ett ökat fokus på egen produktion, för att uppfylla den höga efterfrågan på innehåll, säkra ett innehållsflöde för distribution samt generera nya intäkter.

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The video streaming business has grown substantially during the last decades. To optimize the user experience in video streaming, it is important to know how the user satisfaction relates to the technical qualities for the video streaming services, such as bufferings and startup times.  The Net Promoter Score (NPS) is a widely used management tool used in surveys to measure customer satisfaction and loyalty. The users are categorized into three user groups based on a survey question. This thesis investigates whether it is possible to find correlations between the three user groups based on NPS ratings and measured technical qualities from video streams. Initial data exploring through information visualization suggested that the data should be separated into live streams and video-on-demand. Statistical analysis showed that the NPS user groups have no correlations to how long the users are watching the streams, nor to how long the video takes to start. The results showed, that the users watching live streams seem to be more sensitive to lower qualities than those watching video- on-demand. However, this could also be due to the fact that the measured technical qualities during live streams are generally lower. The buffering and the seek time proved to have correlations to the measured user satisfaction, but several other factors such as the actual video content could also have big impacts on the user’s ratings. The users which had experienced more buffering and longer seek times were more likely to rate the service with a lower score, than the average user. / Mängden videor som streamas över Internet har ökat väsentligt under de senaste årtiondena. För att kunna optimera upplevelsen för de som streamar videor är det viktigt för företagen som erbjuder dessa tjänster att veta hur kundnöjdheten relaterar till de tekniska egenskaperna. Dessa kan inkludera faktorer såsom buffring och starttider. Net Promoter Score (NPS) är ett verktyg som används inom många olika branscher för att mäta kundnöjdhet och lojalitet. Användarna delas in i tre grupper beroende på hur de svarar på en enkätfråga. Detta examensarbete undersöker huruvida det är möjligt att hitta korrelationer mellan kundnöjdhet baserad på de tre användargrupperna från NPS-verktyget och uppmätta tekniska kvaliteter från en streamingtjänst. Efter att inledande informationsvisualiseringar påvisade skillnader mellan live-strömmar och video-on-demand har dessa grupper hanterats separat. Statistisk analys visade att de tre NPS-grupperna inte har några korrelationer med starttiden eller hur länge användarna tittar på videor. Resultatet visade även att användarna som tittar på live-strömmar verkar vara känsligare för lägre tekniska kvaliteter än de som tittar på video-on-demand. Detta kan dock även bero på att de uppmätta tekniska egenskaperna under live-strömmarna generellt är lite lägre. Buffringen och söktiden visade sig ha samband med den uppmätta kundnöjdheten, men flera andra faktorer, såsom det faktiska videoinnehållet, kan också ha en inverkan på användarnas betyg. Användarna som hade upplevt mer buffring och längre söktider var mer benägna att ge tjänsten ett lägre betyg än den genomsnittliga användaren.

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-11-18T11:35:11Z No. of bitstreams: 1 Reinaldo Augusto de Oliveira Ramos.pdf: 4385963 bytes, checksum: 2f3c319e5e8683bc29abfb9359b1a73f (MD5) / Made available in DSpace on 2016-11-18T11:35:11Z (GMT). No. of bitstreams: 1 Reinaldo Augusto de Oliveira Ramos.pdf: 4385963 bytes, checksum: 2f3c319e5e8683bc29abfb9359b1a73f (MD5) Previous issue date: 2016-09-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Pontifícia Universidade Católica de São Paulo / This research aims to examine and analyze the evolution of the concept of linear television in the digital age and the impact that Netflix TV is provoking with Internet distribution of audiovisual content for streaming services. It intends to check how digital technology changes the transmission and distribution of video services, transforming the relationship between consumers and the traditional television industry. In this new paradigm, we have to understand how this mediation is transforming the experience and the perception of its subscribers, when media are understood as “extensions” of the body, taking also in consideration that hybridization or cross media completely changes the landscape of media industries, at times causing the extinction of these media, as in the case of the telegraph, and more recently of the music industry. Netflix took advantage of the opportunities of this new scenario, providing content in almost every screen. The television industry was slow to move in that direction. In this new scenario, we are witnessing the clash between the analog old TVs, cable and open, and new internetTVs, with Netflix as its greatest exponent and a present threat to the old linear programming model. The conclusion suggests a scenario for the emerging television and possible ways of development for this sector. Authors such as Henry Jenkins (2008), Amanda Lotz (2014), Chris Anderson (2006; 2009), Marshall McLuhan (1964/2005) e Lucia Santaella (2007) are the basis of the theoretical framework / Esta dissertação tem como objetivo de pesquisa examinar e analisar a evolução do conceito de televisão linear na era digital e o impacto produzido pelo serviço Netflix, “televisão por internet”, que distribui conteúdo audiovisual por streaming. Pretende verificar como as mudanças tecnológicas digitais de transmissão e distribuição de conteúdo televisivo vêm transformando as relações entre consumidores e a indústria de televisão tradicional. Sendo este um novo paradigma, trata-se de compreender: (a) como essa mediação vem modificando a experiência e a percepção de seus assinantes e usuários, na medida em que os novos serviços funcionam como “extensões” do próprio corpo; (b) como a hibridização ou cruzamento dos meios muda completamente o panorama das indústrias de mídia, por vezes causando até mesmo sua extinção, como ocorreu com o telégrafo e, mais recentemente, com a indústria fonográfica. A Netflix aproveitou as oportunidades desse novo cenário para disponibilizar seu conteúdo em praticamente todas as telas. Já a indústria de televisão demorou a se movimentar nessa direção. Com esse novo panorama, estamos presenciando o embate entre as antigas tevês analógicas, a cabo e aberta, e as novas tevês por internet, que têm na Netflix seu maior expoente, surgindo como ameaça ao antigo modelo de programação linear. Por fim, discute o cenário para onde caminha a emergente televisão, além das possibilidades de desenvolvimento para esse setor. Autores como Henry Jenkins (2008), Amanda Lotz (2014), Chris Anderson (2006; 2009), Marshall McLuhan (1964/2005) e Lucia Santaella (2007) são utilizados como referencial teórico

Στη διατριβή εξετάζουμε προβλήματα που σχετίζονται με τη μετάδοση δεδομένων με υψηλές απαιτήσεις σε εύρος ζώνης και προτείνουμε λύσεις, αλγόριθμους, τεχνικές βελτίωσης της απόδοσης, και εφαρμογές που τις υλοποιούν. Για την περίπτωση του προβλήματος της μετάδοσης βίντεο κατ' απαίτηση (Video on Demand - VoD), εξετάζουμε το πρόβλημα της αποδοχής ή της απόρριψης αιτήσεων για μετάδοση ταινιών χωρίς να υπάρχει γνώση των μελλοντικών αιτήσεων. Παρουσιάζουμε έναν, άμεσης απόκρισης (online), πιθανοτικό αλγόριθμο χρονοπρογραμματισμού ταινιών που εκμεταλλεύεται την γνώση για την κατανομή των προτιμήσεων των αιτήσεων για ταινίες, και αποδεικνύουμε πως έχει ανταγωνιστικό λόγο (competitive ratio) που φράσσεται άνω από σταθερά. Επίσης, δείχνουμε πως η μέθοδος μας μπορεί να επεκταθεί σε ένα προσαρμοζόμενο αλγόριθμο που δεν γνωρίζει την κατανομή των προτιμήσεων. Επίσης, προτείνουμε έναν τρόπο να εφαρμόσουμε μια υπηρεσία βίντεο κατ' απαίτηση για ένα, βασισμένο στο πρωτόκολλο IP, δίκτυο, με περιορισμένο εύρος ζώνης. Στη συνέχεια, εξετάζουμε ένα σχήμα ελέγχου και διαχείρισης του εύρους ζώνης και παρουσιάζουμε ορισμένες μεθόδους προκειμένου να αυξήσουμε την αποδοτικότητα του συστήματος και την εκμετάλλευση του διαθέσιμου εύρους ζώνης (bandwidth). Εξετάζουμε διάφορες τεχνικές και παρουσιάζουμε πειραματικά αποτελέσματα για την βελτίωση της απόδοσης. Επίσης, σχεδιάζουμε και υλοποιούμε μια υπηρεσία διαχείρισης εύρους ζώνης (Managed Bandwidth Service -- MBS). Τέλος παρουσιάζουμε μια ενοποιημένη προσέγγιση για την μετάδοση υπερμεσικών/πολυμεσικών αντικειμένων, τα οποία παρουσιάζονται με βάση προκαθορισμένα σενάρια παρουσίασης (με χωροχρονικές αλληλοεξαρτήσεις μεταξύ των διάφορων μέσων). Τα υπερμεσικά αντικείμενα δομούνται σύμφωνα με μία γλώσσα σηματοδότησης, μέσω της οποίας διατηρούνται πληροφορίες για τις χωρικές και χρονικές συσχετίσεις. Επίσης, υλοποιούμε ένα τέτοιο σύστημα μετάδοσης, που εφαρμόζουμε για εκπαίδευση από απόσταση. / In this thesis we investigate problems related to the transmission of data with high demands in terms of bandwidth, and we propose solutions, algorithms, techniques to increase performance, and applications that use them. For the case of the online video on demand problem, we investigate the problem of having to accept or reject a request for a movie without knowing the future requests. We present an online movie-scheduling scheme that exploits the knowledge of the distribution of the preference of requests for movies, and is shown to have a competitive ratio bounded above by a constant. We extend our approach by presenting an adaptive randomized scheduler which is not aware of the movie popularities. In the sequel we propose a way to implement a video on demand service over a limited bandwidth/best effort Internet based network. Ιn the sequel, we consider a bandwidth control scheme, and we present some methods to increase the efficiency of the system and the utilisation of the available bandwidth. We consider different techniques and we present experimental results for the increased performance. We, also, design and implement a Managed Bandwidth Service (MBS) . Finally, we present a unified approach for delivering hypermedia/multimedia objects, that are to be presented according to predefined scenarios (with spatial and temporal relationships between the various media). The hypermedia documents are structured using a hypermedia markup language that keeps information of the spatiotemporal relationships among document's media components. We, also, implement such a multimedia transmission system, and apply it to distance learning.

Syfte: Vi vill ta reda på hur teknikutvecklingen relaterad till VoD påverkar beteendet hos unga vuxna och hur detta beteende förändrar tv-tittandet i denna målgrupp. Teori: Denna studie använder huvudsakligen två teorier för att undersöka problemet. Den första teori som tas upp är Diffusion of innovation, Rogers (2003) som diskuterar innovationers spridning och påverkan i samhället. För att vidare undersöka beteendet hos unga vuxna används Jakob Bjurs avhandling Transforming Audiences (2009) som undersöker individualiseringens mönster inom tv-tittande. Metod: En kvalitativ empirisk fallstudie baserad på intervjuer av fokusgrupper samt personintervju. Detta stöds av en kvantitativ undersökning i syfte att skapa en triangulering för att minimera risken för en felaktig tolkning av resultatet. Resultat: Unga vuxna vill inte längre anpassa sig till tv-tablåer. Generationen blir allt mer individualiserad och vill därför välja helt på egen hand var och när de skall titta på exempelvis ett tv-program. Medieföretagen är medvetna om detta skifte från linjär-tv till VoD och således finns ett fokus på att utveckla ett mer individ-anpassat tittande. Trots individualiseringen och de förbättrade VoD-tjänsterna vill många se bland annat nyheter, större sportevenemang samt melodifestivalen via linjär-tv. Slutsats: Den största anledningen till att många gör denna övergång från linjär-tv till VoD är att de söker en flexibilitet som linjär-tv inte kan erbjuda. Flexibiliteten har gjorts möjlig genom den teknikutveckling som skett inom datorer, smarttelefoner och surfplattor. Det som lockar många VoD-användare till att fortfarande titta på linjär-tv är de sändningar som är viktiga att se i realtid. Tack vare dessa kommer förmodligen tv-tittandet finnas kvar en tid framöver, dock ser vi sjunkande tittarsiffror i de yngre generationerna vilket gör framtiden för linjär-tv oviss.

Techn. University, Diss., 2003--Darmstadt.