Le trafic vidéo a subi une augmentation fulgurante sur Internet ces dernières années. Pour pallier à cette importante demande de contenu vidéo, la technologie du streaming adaptatif sur HTTP est utilisée. Elle est devenue par ailleurs très populaire car elle a été adoptée par les différents acteurs du domaine de la vidéo streaming. C’est une technologie moins couteuse qui permet aux fournisseurs de contenu, la réutilisation des serveurs web et des caches déjà déployés. En plus, elle est exempt de tout blocage car elle traverse facilement les pare-feux et les translations d’adresses sur Internet. Dans cette thèse, nous proposons une nouvelle méthode de vidéo streaming adaptatif appelé “Backward-Shifted Coding (BSC)”. Il se veut être une solution complémentaire au standard DASH, le streaming adaptatif et dynamique utilisant le protocole HTTP. Nous allons d’abord décrire ce qu’est la technologie BSC qui se base sur le codec (encodeur décodeur) à multi couches SVC, un algorithme de compression extensible ou évolutif. Nous détaillons aussi l’implémentation de BSC dans un environnement DASH. Ensuite,nous réalisons une évaluation analytique de BSC en utilisant des résultats standards de la théorie des files d’attente. Les résultats de cette analyse mathématique montrent que le protocole BSC permet de réduire considérablement le risque d’interruption de la vidéo pendant la lecture, ce dernier étant très pénalisant pour les utilisateurs. Ces résultats vont nous permettre de concevoir des algorithmes d’adaptation de qualité à la bande passante en vue d’améliorer l’expérience utilisateur. Ces algorithmes permettent d’améliorer la qualité de la vidéo même étant dans un environnement où le débit utilisateur est très instable.La dernière étape de la thèse consiste à la conception de stratégies de caching pour optimiser la transmission de contenu vidéo utilisant le codec SVC. En effet, dans le réseau, des serveurs de cache sont déployés dans le but de rapprocher le contenu vidéo auprès des utilisateurs pour réduire les délais de transmission et améliorer la qualité de la vidéo. Nous utilisons la programmation linéaire pour obtenir la solution optimale de caching afin de le comparer avec nos algorithmes proposés. Nous montrons que ces algorithmes augmentent la performance du système tout en permettant de décharger les liens de transmission du réseau cœur. / Due to the growth of video traffic over the Internet in recent years, HTTP AdaptiveStreaming (HAS) solution becomes the most popular streaming technology because ithas been succesfully adopted by the different actors in Internet video ecosystem. Itallows the service providers to use traditional stateless web servers and mobile edgecaches for streaming videos. Further, it allows users to access media content frombehind Firewalls and NATs.In this thesis we focus on the design of a novel video streaming delivery solutioncalled Backward-Shifted Coding (BSC), a complementary solution to Dynamic AdaptiveStreaming over HTTP (DASH), the standard version of HAS. We first describe theBackward-Shifted Coding scheme architecture based on the multi-layer Scalable VideoCoding (SVC). We also discuss the implementation of BSC protocol in DASH environment.Then, we perform the analytical evaluation of the Backward-Sihifted Codingusing results from queueing theory. The analytical results show that BSC considerablydecreases the video playback interruption which is the worst event that users can experienceduring the video session. Therefore, we design bitrate adaptation algorithms inorder to enhance the Quality of Experience (QoE) of the users in DASH/BSC system.The results of the proposed adaptation algorithms show that the flexibility of BSC allowsus to improve both the video quality and the variations of the quality during thestreaming session.Finally, we propose new caching policies to be used with video contents encodedusing SVC. Indeed, in DASH/BSC system, cache servers are deployed to make contentsclosed to the users in order to reduce network latency and improve user-perceived experience.We use Linear Programming to obtain optimal static cache composition tocompare with the results of our proposed algorithms. We show that these algorithmsincrease the system overall hit ratio and offload the backhaul links by decreasing thefetched content from the origin web servers.

Orientador: Prof. Dr. Carlos Alberto Kamienski / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia da Informação, 2016. / Atualmente é comum as pessoas se conectarem à Internet em lugares públicos como praças, parques e bibliotecas. Algumas cidades oferecem conexão gratuita por WiFi, onde os usuários utilizam a Internet para diversas finalidades, como buscar informações, trocar mensagens e assistir a mídias digitais. A abordagem deste trabalho é a utilização de streaming de vídeo em praças digitais distribuídas pelas diversas regiões da cidade de São Paulo. Foram realizadas análises de desempenho do serviço prestado à comunidade nas cento e vinte praças do programa "WiFi Livre SP", no período de um ano. Para isso, foram utilizadas métricas que avaliam tanto a Qualidade de Experiência (QoE) do usuário, como a Qualidade de Serviço (QoS) da rede. Como resultado, obteve-se uma nova ferramenta de avaliação da Qualidade de Experiência dos usuários em transmissões de streaming de vídeo, bem como as características das praças em relação aos dados analisados, os quais mostram que, para diferentes praças, dias e níveis de qualidade de vídeo, na maioria das vezes, o uso é satisfatório para determinados fins. / Currently it is common for people to connect to the Internet in public places such as squares, parks and libraries. Some cities offer free connection by WiFi, where users use the Internet for various purposes, such as searching for information, exchange messages and watch digital media. The approach of this work is the use of video streaming in digital squares distributed among different regions of São Paulo. Performance tests of this service to the community were carried out in the 120 squares belonging to the "WiFi Livre SP program" in one year. For this we used metrics that assess both the Quality of Experience (QoE) of the user, such as Quality of Service (QoS) network. As a result we obtained a new evaluation tool of Quality of Experience of users in streaming videos, and the characteristics of the squares on the data analyzed which show that for different places, days and levels of video quality, in most of the time the use is satisfactory for particular purposes.

Continuous improvements to the state of the art have made it easier to create, send and receive vast quantities of video over the Internet. Catalysed by these developments, video is now the largest, and fastest growing type of traffic on modern IP networks. In 2015, video was responsible for 70% of all traffic on the Internet, with an compound annual growth rate of 27%. On the other hand, concerns about the growing energy consumption of ICT in general, continue to rise. It is not surprising that there is a significant energy cost associated with these extensive video usage patterns. In this thesis, I examine the energy consumption of typical video configurations during decoding (playback) and encoding through empirical measurements on an experimental test-bed. I then make extrapolations to a global scale to show the opportunity for significant energy savings, achievable by simple modifications to these video configurations. Based on insights gained from these measurements, I propose a novel, energy-aware Quality of Experience (QoE) metric for digital video - the Energy - Video Quality Index (EnVI). Then, I present and evaluate vEQ-benchmark, a benchmarking and measurement tool for the purpose of generating EnVI scores. The tool enables fine-grained resource-usage analyses on video playback systems, and facilitates the creation of statistical models of power usage for these systems. I propose GreenDASH, an energy-aware extension of the existing Dynamic Adaptive Streaming over HTTP standard (DASH). GreenDASH incorporates relevant energy-usage and video quality information into the existing standard. It could enable dynamic, energy-aware adaptation for video in response to energy-usage and user ‘green' preferences. I also evaluate the subjective perception of such energy-aware, adaptive video streaming by means of a user study featuring 36 participants. I examine how video may be adapted to save energy without a significant impact on the Quality of Experience of these users. In summary, this thesis highlights the significant opportunities for energy savings if Internet users gain an awareness about their energy usage, and presents a technical discussion how this can be achieved by straightforward extensions to the current state of the art.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-06T14:59:44Z No. of bitstreams: 1 biancaportesdecastro.pdf: 1203353 bytes, checksum: 0cd5843bff9e747e5432fff99ec1e565 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-07T11:04:29Z (GMT) No. of bitstreams: 1 biancaportesdecastro.pdf: 1203353 bytes, checksum: 0cd5843bff9e747e5432fff99ec1e565 (MD5) / Made available in DSpace on 2017-06-07T11:04:29Z (GMT). No. of bitstreams: 1 biancaportesdecastro.pdf: 1203353 bytes, checksum: 0cd5843bff9e747e5432fff99ec1e565 (MD5) Previous issue date: 2014-08-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Aplicações multimídia são muito populares na internet. Grande parte delas necessita de multicast para escalar. É sabido que multicast em nível de redes não foi implementado como desejado. Protocolos em nível de aplicação são a solução atual. Apesar do sucesso dos protocolos ALM (Application Layer Multicast), a maioria dos protocolos existentes são custosos e acarretam grande sobrecarga de controle à rede. Neste trabalho, apresentamos um novo protocolo de fluxo contínuo baseado em árvore, utilizando a desigualdade triangular entre cada três peers para gerenciamento dinâmico da topologia (o PALMS+). O novo protocolo é simples e com baixa sobrecarga. Mesmo assim, seu desempenho é tão bom quanto o estado da arte. Experimentos realizados na plataforma Oversim (OMNet++) demonstraram que o PALMS+ manteve desempenho tão bom quanto o estado da arte (e.g. protocolo NICE), mesmo quando submetido a alto churn em uma rede heterogênea. De fato, a sobrecarga nos peers do novo protocolo é menor que 10% da sobrecarga gerada pelo NICE. O protocolo PALMS+ entrega os dados em menos de 1,5s. O novo protocolo mostra-se adequado a vídeo ao vivo, escalando mesmo em cenários realistas e com alto churn. / Multimedia applications are very popular on the internet. Many of these applications need multicast to scale. However, network layer multicast has not been implemented in the internet. Application layer multicast (ALM) protocols are a practical alternative. However, despite their popularity, many existing ALM protocols and mechanisms are expensive and bring a large overhead control on the network. In the present work, a new protocol is proposed for content distribution based on tree, using the triangular inequality between every three peers to dynamic topology control (the PALMS+). The new protocol is simple and with low overhead. Nevertheless, its performance as good as the state of the art. Experimental results conducted with the OverSim platform (OMNet++) suggest that PALMS+ improves the performance of a state-of-art implementation of ALM protocol when compared against the NICE protocol. Furthermore, the control message overhead at peers using the PALMS+ protocol is reduced by 10%, when compared with NICE. In the PALMS+ protocol, chunks are delivered up to 1,5s. Results confirm that proposed implementation of PALMS+ is very suitable to real-time video streaming, even when churn is high.

Context: Video streaming over best-effort networks is complicated by a number of factors including unknown and time-varying bandwidth, transmission delay, and high packet losses. Excessive packet loss can causes significant degradation in quality of video perceived by users of real-time video applications. Recent studies suggest that error control schemes using Forward Error Correction (FEC) is a good candidate for decreasing the negative impact of packet loss on video quality. With FEC scheme, redundant information is transmitted along with the original information so that the lost original video data can be recovered at least in part from the redundant information. Although sending additional redundancy increases the probability of recovering lost packets, it also increases the bandwidth requirements which in turn increase loss rate of the video stream due to congestion. For this reason FEC is characterized as effective when the redundancy is sufficient to recover the lost data, ineffective when the redundancy is little to recover the lost data and inefficient when the redundancy is high for the lost data. To provide best performance for the streaming application and the network, it is important to determine, in real time, the proper amount of redundant information according to the loss behavior of the network. However it not clears how to choose optimal redundancy given the constraints mentioned above at any given point in time. Objective: This thesis investigated the limitations of existing static FEC schemes and suggested alternative approaches that can achieve effectiveness through sending the appropriate amount of FEC redundancy in real-time. Three dynamic redundancy adaptation control systems On-Off, Proportional, Proportional-Integral have been design and implemented based on existing conventional FEC mechanisms. Moreover the performance evaluation of each mechanism is performed on simulated environment. Method: A performance evaluation methodology using network simulation and key evaluation criteria to test the mechanisms under different network conditions and the scenarios for each different network are considered. The proposed mechanisms were implemented in a simulation environment by using NS2. After the implementation and validation of the techniques, several simulation experiments have been conducted to study the performance of each redundancy adjustment schemes. Results: The result of the simulation experiments and performance analysis showed that both Proportional and Proportional-Integral (PI) redundancy controller based on Adaptive Forward Error Correction (AFEC) mechanisms significantly reduce the number of discarded video blocks as compared with the On-Off based scheme. On the other hand On-Off based AFEC mechanisms added small number of excess redundancy. The amount of excess redundancy added by the Proportional and PI controllers significantly increases as the packet drop rate of the transmission channel increases. Conclusion: Based on the findings of this study, using the PI adaptation based AFEC mechanisms is potentially viable option for enhancing the performance of video streaming applications over the network. / +46762356096 +251929003705/+46739691250

Mobile Video streaming has become popular with the arrival of high capability smart phones on Mobile Networks. Users are streaming high definition (HD) videos and have high expectations on Mobile Quality of Experience (QoE). Fourth Generation Mobile Networks are being deployed recently in many regions of the world and have capability to efficiently handle high definition video traffic. YouTube is one of the most extensively used Video on Demand Service on smart phones where wide range of people do video streaming. Most of the QoE experiments on 4g networks have been conducted in lab environment but they do not capture the daily routine of user experience on viewing videos. The user experiments in this thesis are conducted in natural life settings to capture Quality of Experience based on context of the user location. User experiments are designed and conducted for collecting Mean Opinion scores (MOS) in four different context based locations and have been collected using Experience Sampling Method (ESM). The Contribution of thesis is applying linear mixed effect Modeling on data collected to develop Quality of Experience (QoE) models of video streaming for Mobile YouTube on 4G Network. This thesis is one of the first works on modeling QoE experience at different context based physical locations in natural settings for mobile YouTube video streaming in 4G networks.

This thesis work regards free viewpoint TV. The main idea is that users can switch between multiple streams in order to find views of their own choice. The purpose is to provide fast switching between the streams, so that users experience less delay while view switching. In this thesis work we will discuss different video stream switching methods in detail. Then we will discuss issues related to those stream switching methods, including transmission and switching. We shall also discuss different scenarios for fast stream switching in order to make services more interactive by minimizing delays. Stream switching time varies from live to recorded events. Quality of service (QoS) is another factor to consider which can be improved by assigning priorities to the packets. We will discuss simultaneous stream transmission methods which are based on predictions and reduced quality streams for providing fast switching. We will present prediction algorithm for viewpoint prediction, propose system model for fast viewpoint switching and make evaluation of simultaneous stream transmission methods for free viewpoint TV. Finally, we draw our conclusions and propose future work. / Degree project

A drastic increase in traffic of mobile broadband is seen in the past few years, which is further accelerated by the increase in usage of smart phones and its applications. The availability of good smart phones and better data connectivity are encouraging mobile users to use video services. This huge increase in usage will pose a lot of challenges to the wireless networks. The wireless network has to become content aware in order to offer enhanced quality of video service through efficient utilization of the wireless spectrum. This thesis focuses on improving the Quality of Experience (QoE) for video transmission over Long Term Evolution (LTE) networks by imparting the content awareness to the system and providing unequal error protection for critical video packets. Two different schemes for the improvement of video quality delivery over LTE networks are presented in this thesis. Using content awareness, the retransmission count of Hybrid Automatic Repeat reQuest (HARQ) are changed dynamically such that the most important video frame gets more number of retransmission attempts, which increases its success for delivery in-turn increasing the received video quality. Since Radio Link Control (RLC) is the link layer for radio interface, the second approach focuses on optimizing this layer for efficient video transmission. As part of this scheme, a new operation mode called Hybrid Mode (HM) for RLC is defined. This mode performs retransmission only for the critical video frames, leaving other frames to unacknowledged transmission. The simulation results of both proposed schemes provide significant improvement in achieving good video quality without affecting the system performance.

Magister Scientiae - MSc / In South Africa, Deaf people communicate with one another and the broader community by means of South African Sign Language. The majority of Deaf people who have access to a mobile phone (cell phone) use Short Message Service (SMS) to communicate and share information with hearing people, but seldom use it among themselves. It is assumed that video messaging will be more accessible to Deaf people, since their level of literacy may prevent them from making effective use of information that is disseminated via texting/SMS. The principal objective of the esearch was to explore a cost-effective and efficient mass multimedia messaging system. The intention was to adapt a successful text-based mass notification system, developed by a local nongovernmental organization (NGO), to accommodate efficient and affordable video mass messaging for Deaf people. The questions that underpin this research are: How should video- streaming mass-messaging methods be compared and evaluated to find the most suitable method to deliver an affordable and acceptable service to Deaf people? What transport vehicles should be considered: Multimedia Message Service (MMS), the web, electronic mail, or a cell phone resident push/pullapplication? Which is the most cost effective? And, finally: How does the video quality of the various transport vehicles differ in terms of the clarity of the sign language as perceived by the Deaf? The soft-systems methodology and a mixed-methods methodology were used to address the research questions. The soft-systems methodology was followed to manage the research process and the mixed-methods research methodology was followed to collect data. Data was collected by means of experiments and semi-structured interviews. A prototype for mobile phone usage was developed and evaluated with Deaf members the NGO Deaf Community of Cape Town. The technology and internet usage of the Deaf participants provided background information. The Statistical Package for Social Science (SPSS) was used to analyse the quantitative data, and content analysis was used to analyse the documents and interviews. All of the Deaf participants used their mobile phones for SMS and the majority (81.25%) used English to type messages; however, all indicated that they would have preferred to use South Africa sign language on their mobile phones if it were available. And they were quite willing to pay between 75c and 80c per message for using such a video-messaging service.Of the transport vehicles demonstrated, most Deaf people indic indicated that they preferred to use the SMS prototype (with a web link to the video) rather than the MMS prototype with the video attached. They were, however, very concerned about the cost of using the system, as well as the quality of the sign language videos. / South Africa

Virtualization on top of high-performance servers has enabled the virtualization of network functions like caching, deep packet inspection, etc. Such Network Function Virtualization (NFV) is used to dynamically adapt to changes in network traffic and application popularity. We demonstrate how the combination of Software Defined Networking (SDN) and NFV can support the parallel operation of different Internet architectures on top of the same physical hardware. We introduce our architecture for this approach in an actual test setup, using CloudLab resources. We start of our evaluation in a small setup where we evaluate the feasibility of the SDN and NFV architecture and incrementally increase the complexity of the setup to run a live video streaming application. We use two vastly different protocol stacks, namely TCP/IP and NDN to demonstrate the capability of our approach. The evaluation of our approach shows that it introduces a new level of flexibility when it comes to operation of different Internet architectures on top of the same physical network and with this flexibility provides the ability to switch between the two protocol stacks depending on the application.