Dans cette thèse nous proposons de nouvelles techniques et de nouveaux algorithmes pour améliorer la qualité des applications de streaming vidéo sur Internet. Nous formulons des problèmes d'optimisation et obtenons des politiques de contrôle pour la transmission sur le réseau Internet actuel sans qualité de service. Cette thèse étudie des techniques qui adaptent la transmission à la fois aux conditions variables du réseau (adaptation au réseau) et aux caractéristiques des vidéos transmises (adaptation au contenu). Ces techniques sont associées au codage en couche de la vidéo et au stockage temporaire de la vidéo au client. Nous évaluons leurs performances à partir de simulations avec des traces réseau (connexions TCP) et à partir de vidéos encodées en MPEG-4 FGS. Nous considérons tout d'abord des vidéos stockées sur un serveur et transmises sur une connexion TCP-compatible sans perte. Nous comparons les mécanismes d'ajout/retranchement de couches et de changement de versions; nous montrons que la flexibilité du codage en couches ne peut pas compenser, en général, le surcoût en bande passante par rapport au codage vidéo conventionnel. Deuxièmement, nous nous concentrons sur une nouvelle technique de codage en couches, la scalabilité à granularité fine (dite FGS), qui a été conçue spécifiquement pour le streaming vidéo. Nous proposons un nouveau cadre d'étude pour le streaming de vidéos FGS et nous résolvons un problème d'optimisation pour un critère qui implique la qualité des images et les variations de qualité durant l'affichage. Notre problème d'optimisation suggère une heuristique en temps réel dont les performances sont évaluées sur des protocoles TCP-compatibles différents. Nous montrons que la transmission sur une connexion TCP-compatible très variable, telle que TCP, résulte en une qualité comparable à une transmission sur des connexions TCP-compatibles moins variables. Nous présentons l'implémentation de notre heuristique d'adaptation dans un système de streaming de vidéos MPEG-4. Troisièmement, nous considérons le cadre d'étude général du streaming optimisé suivant les caractéristiques débit-distorsion de la vidéo. Nous analysons des traces débit-distorsion de vidéos de longue durée encodées en MPEG-4 FGS, et nous observons que le contenu sémantique a un impact important sur les propriétés des vidéos encodées. A partir de nos traces, nous examinons le streaming optimal à différents niveaux d'agrégation (images, groupes d'images, scènes); nous préconisons l'adaptation optimale scène par scène, qui donne une bonne qualité pour une faible complexité de calcul. Finalement, nous proposons un cadre d'optimisation unifié pour la transmission de vidéos encodées en couches sur des canaux à pertes. Le cadre d'étude proposé combine l'ordonnancement, la protection contre les erreurs par les FEC et la dissimulation d'erreur au décodeur. Nous utilisons des résultats sur les Processus de Décision de Markov (MDPs) à horizon infini et gain moyen, pour trouver des politiques de transmission optimales avec une faible complexité et pour un large éventail de mesures de qualité. Nous montrons qu'il est crucial de considérer la dissimulation d'erreur au décodeur dans la procédure d'optimisation de l'ordonnancement et de la protection contre les erreurs afin d'obtenir une transmission optimale.

<p>SVT is Sweden’s largest TV-network and broadcasts more then 22 000 hours of TV each year. SVT is a public service company where the basic idea is to reflect the world from different perspectives and news is very important for providing neutral and versatile information in a variety of areas. An important part of the flow of information is to continuously receive reports from all corners of the world around the clock. This places very high demands on the technology used and it is important that it function and develops to meet current and future growing needs. One of SVTs vision is to increase the proportion of live reports in news broadcasts and self produced news reports from remote locations and is therefore interested in new technologies that offer greater topicality and lower cost for the reports. There are two different technologies used in the present situation, Store and Forward and Live. The difference between them is that at the Store and Forward the reporter sends a complete edited feature back to the news room. When doing a Live the reporter simply performs a live reporting. During the project a technical comparison between today’s products has been performed, the comparison has highlighted advantages and disadvantages of these products video and audio coding and data transmission. Even a comparison of their ease of use and functionality has been conducted and results are to be the basis for a set of requirements for additional procurement of large scale purchases of new systems. The results have shown that the system from the English company Quicklink is the one that performs best image quality overall for both Store and Forward and Live. The system has a well working interface with many smart features and is also easy to use in a large scale environment. All these features make the application from Quicklink best suited for SVTs needs.</p>

<p>Realisering av streamingtjenester i P2P-nettverk er en utfordring fordi slike nettverk er preget av dynamikk og stadige endringer i forhold til nodenes tilgjengelighet. Hvis en node som leverer en mediestrøm blir utilgjengelig, vil det oppstå avbrudd i avspillingen hos mottakernoden. Utgangspunktet for denne hovedoppgaven er et ønske om å kunne gjøre streaming med tilfredsstillende tjenestekvalitet til en realitet i P2P-nettverk. Målet er å spesifisere en metode som bidrar til å forbedre den opplevde ressurstilgjengeligheten i slike nettverk.</p><p>P2P-systemer kjennetegnes generelt ved at de består av noder på randen av Internett, at samtlige noder bidrar med ressurser og kommuniserer direkte med hverandre og at hver node er en selvstyrende enhet. Det finnes to hovedkategorier P2P-systemer, “ekte” og “hybride”, samt en rekke applikasjonsområder. Streaming innebærer at innholdsleveranse gjøres i sanntid. Sanntidsleveranse krever at data leveres til mottaker i tide og at pakker leveres i rett rekkefølge. I P2P-nettverk, hvor omgivelsene preges av dynamikk og heterogenitet, er dette en stor utfordring. Flere teknikker kan benyttes for å håndtere slike omgivelser, men utfordringene knyttet til tilgjengelighet framstår som uløste og samtidig kritiske med tanke på oppnåelig tjenestekvalitet.</p><p>Vårt bidrag i retning av å forbedre den opplevde ressurstilgjengeligheten er en metode som blant annet benytter multinodestreaming som leveranseteknikk. Multinodestreaming innebærer å dele en strøm i flere delstrømmer og hente disse fra forskjellige noder. Delstrømmene kan da flettes ved mottak og spilles av som én strøm. Konsekvensen av at en node blir utilgjengelig vil kun bli kvalitetsdegradering av avspillingen, og ikke totalt avspillingsbrudd. Tilgjengeligheten kan forbedres ytterligere ved å utføre effektiv overtakelse av tapte delstrømmer. Ved å implementere metoden i en prototyp, er det mulig å teste dens funksjon og effekt. Testene viser at kvalitetsdegraderingen på avspillingen, som følge av at en node blir utilgjengelig, kun er midlertidig hvis en annen node kan overta leveransen. Reetablering av en delstrøm kan gjøres på gjennomsnittlig 4,7 sekunder. Enkeltnodestreaming ville til sammenligning medført fullt avspillingsbrudd. Resultatene sannsynliggjør derfor at multinodestreaming kan bidra til å forbedre den opplevde ressurstilgjengeligheten for streamingtjenester i P2P-nettverk.</p>

StreamIt is a language specifically designed for modern streaming applications. A certain important class of these applications operates on streams of bits. This paper presents the motivation for a bit-packing optimization to be implemented in the StreamIt compiler for the RAW Architecture. This technique aims to pack bits into integers so that operations can be performed on multiple bits at once thus increasing the performance of these applications considerably. This paper gives some simple example applications to illustrate the various conditions where this technique can be applied and also analyses some of its limitations. / Singapore-MIT Alliance (SMA)

Realisering av streamingtjenester i P2P-nettverk er en utfordring fordi slike nettverk er preget av dynamikk og stadige endringer i forhold til nodenes tilgjengelighet. Hvis en node som leverer en mediestrøm blir utilgjengelig, vil det oppstå avbrudd i avspillingen hos mottakernoden. Utgangspunktet for denne hovedoppgaven er et ønske om å kunne gjøre streaming med tilfredsstillende tjenestekvalitet til en realitet i P2P-nettverk. Målet er å spesifisere en metode som bidrar til å forbedre den opplevde ressurstilgjengeligheten i slike nettverk. P2P-systemer kjennetegnes generelt ved at de består av noder på randen av Internett, at samtlige noder bidrar med ressurser og kommuniserer direkte med hverandre og at hver node er en selvstyrende enhet. Det finnes to hovedkategorier P2P-systemer, “ekte” og “hybride”, samt en rekke applikasjonsområder. Streaming innebærer at innholdsleveranse gjøres i sanntid. Sanntidsleveranse krever at data leveres til mottaker i tide og at pakker leveres i rett rekkefølge. I P2P-nettverk, hvor omgivelsene preges av dynamikk og heterogenitet, er dette en stor utfordring. Flere teknikker kan benyttes for å håndtere slike omgivelser, men utfordringene knyttet til tilgjengelighet framstår som uløste og samtidig kritiske med tanke på oppnåelig tjenestekvalitet. Vårt bidrag i retning av å forbedre den opplevde ressurstilgjengeligheten er en metode som blant annet benytter multinodestreaming som leveranseteknikk. Multinodestreaming innebærer å dele en strøm i flere delstrømmer og hente disse fra forskjellige noder. Delstrømmene kan da flettes ved mottak og spilles av som én strøm. Konsekvensen av at en node blir utilgjengelig vil kun bli kvalitetsdegradering av avspillingen, og ikke totalt avspillingsbrudd. Tilgjengeligheten kan forbedres ytterligere ved å utføre effektiv overtakelse av tapte delstrømmer. Ved å implementere metoden i en prototyp, er det mulig å teste dens funksjon og effekt. Testene viser at kvalitetsdegraderingen på avspillingen, som følge av at en node blir utilgjengelig, kun er midlertidig hvis en annen node kan overta leveransen. Reetablering av en delstrøm kan gjøres på gjennomsnittlig 4,7 sekunder. Enkeltnodestreaming ville til sammenligning medført fullt avspillingsbrudd. Resultatene sannsynliggjør derfor at multinodestreaming kan bidra til å forbedre den opplevde ressurstilgjengeligheten for streamingtjenester i P2P-nettverk.

The aim of this study is to understand how leaders in the Canadian radio industry perceive the nascent personalized music streaming service industry, and how those perceptions inform their current business decisions. Over the last few years, Internet-based music services like Deezer and Rdio have launched in Canada, providing listeners with the opportunity of an alternative music experience to conventional broadcast radio. Through five interviews with experts representing terrestrial radio, on-demand services and regulation, three scenarios are presented for the future of conventional radio. In addition, a conceptualized listener profile is created using Grounded Theory Method. This profile buttresses the central finding of this research: should key political, economic and social factors remain in place, conventional radio is likely to continue to dominate as the leading commercial audio platform for Canadians in the years to come.

The recent advances in mobile computing devices and wireless networking produced the technical platform for multimedia services over thin mobile devices. Nowadays, we are witnessing an important growth in applications using thin mobile devices, such as social networks, virtual walkthrough, media streaming, and augmented reality (AR), just to mention a few. Most of these applications are based on the client-server architecture, however several studies showed that the client-server architecture suffers from various issues, such as the server bottleneck, latency and the lack of scalability. This led most of the systems to switch to the peer-to-peer (P2P)-like environment for its scalability and potential cost saving. P2P multimedia streaming over thin mobile devices-based classes of applications has known a significant growth during the last years. Although P2P video streaming over thin mobile devices received a great deal of attention, the application of 3D streaming over mobile devices was challenging mainly due to the limited mobile resources and capabilities, as well as the wireless medium limitations. Having 3D streaming over Mobile Ad hoc Networks (MANET) is considered more challenging given that the 3D streaming-based system has to deal with a dynamic environment resulting from nodes mobility, which may lead to route breakages and connection loss. Therefore, one of the major difficulties in 3D streaming over MANET is related to the supplying partner's strategy that aims at determining the most suitable source holding the required 3D data to stream it quickly and efficiently to the requesters. In this thesis, we propose our P2P based 3D streaming system which we refer to as MOSAIC as well as a suite of supplying partner strategy protocols for P2P 3D streaming over thin mobile devices. Our proposed suite of protocols selects the potential sources that have the relevant 3D data, based on a set of criteria such as the source location, the mobile device's available resources as well as its residual energy. We also proposed a multihop supplying partner selection protocol that takes into account the signal strength and the nodes mobility when streaming the relevant 3D data. The performance evaluation obtained to evaluate our MOSAIC system as well as our suite of protocols using an extensive set of NS2 simulation experiments, is then reported.

Video dissemination capabilities are crucial for the deployment of many services over VANETs. These services range from enhancing safety via the dissemination of video from the scene of an accident, to advertisement of local services or businesses. This work considers the infrastructure-less scenario of VANETs and dissemination of video content over this network environment, which is extremely challenging mainly due to its dynamic topology and stringent requirements for video streaming. This study discusses issues and challenges that need to be tackled for disseminating high-quality video over VANETs. Furthermore it surveys and analyzes the suitability of different existing solutions aimed towards effective and efficient techniques for video dissemination in vehicular networks. As a result, a set of the most promising techniques are selected, described in detail and evaluated based on standard terms in quality of service. This thesis also discusses efficiency and suitability of these techniques for video dissemination and compares their performance over the same network condition. In addition, a detailed study on the effect of network coding on video dissemination protocols has been conducted to guide how to employ this technique properly for video streaming over VANETs. From this study, a summary of the observations was obtained and used to design a new hybrid solution by deploying robust and efficient techniques in number of existing protocols in an optimal manner. The proposed hybrid video dissemination protocol outperforms other protocols in term of delivery ratio and complies with other quality-of-service requirements for video broadcasting over vehicular environments.

This qualitative case-study research investigated how Eastern European immigrant youth in a southern English public secondary school adjusted to and experienced the British educational system, which involves streaming students into levels of academic ability. The study focused on these students experiences of day-to-day life in a British secondary school and it explored the challenges and successes that they experienced. The study also investigated the experiences of teachers and administrators involved in the education of immigrant students. Through the use of student and faculty experiences, through recorded interviews, this study sought to understand how educators could improve the ways they are educating immigrant students.

Video streaming applications over wireless networks have turned out to be immensely popular recently. In this thesis, we first study the buffering schemes for the VBR video streaming in heterogeneous wireless networks. An analytical framework is presented to derive the expected number of jitters and average buffering delay. Through experimenting with a wide range of buffering schemes, we quantify the bene¯t of incorporating user location information in streaming over heterogeneous wireless networks. Second, we consider the delivery of scalable VBR video streams over wireless channels. We propose adaptive rate control algorithms to improve the combined system performance of video frame quality and playout smoothness based on the feedback information of wireless network estimation, buffer content and playback situation. The proposed adaptive rate control algorithms provide significantly improved streaming quality compared with the non-control policy.