To provide universal multimedia experience, multimedia streaming services need to transparently handle the variation and heterogeneity in operating environment. From the standpoint of streaming application, video adaptation techniques are intended to cope with the environmental variations by utilizing manipulations of the video content itself. Scalable video coding (SVC) schemes, like that suggested by the standards H.264 and its SVC extension, is highly attractive for designing a self-adaptive video streaming system. When SVC is employed in streaming system, the produced video stream can be then easily truncated or tailored to form several sub-streams which can be decoded separately to obtain a range of preferable picture size, quality and frame rate. However, questions about how to perform the adaptation using SVC and how much adaptation SVC enables are still remaining research issues. We still lack a thorough understanding of how to automate the scaling procedure in order to achieve an optimal video Quality-of-Experience for end users. Video QoE, depends highly on human perception. In this thesis, we introduce several video QoE studies around the usability of H.264 SVC. Several factors that contribute significantly to the overall QoEs have been identified and evaluated in these studies. As an example of application usage related factor, playback smoothness and application response time are critical performance measures which can benefit from temporal scalability. Targeting on applications that requires frequent interactivity, we propose a transcoding scheme that fully utilizes the benefits of Switching P and Switching I frames specified in H.264 to enhance video stream's temporal scalability.  Focusing on visual quality related factors, a series of carefully designed subjective quality assessment tests have been performed on mobile devices to investigate the effects of multi-dimensional scalability on human quality perception. Our study reveals that QoE degrades non-monotonically with bitrate and that scaling order preferences are content-dependent. Another study find out that the flickering effect caused by frequent switching between layers in SVC compliant bit-streams is highly related to the switching period. When the period is above a certain threshold, the flickering effect will disappear and layer switching should not be considered as harmful. We have also examined user perceived video quality in 3D virtual worlds. Our results show that the avatars' distance to the virtual screen in 3D worlds contribute significant to the video QoE, i.e., for a wide extent of distortion, there exists always a feasible virtual distance from where the distortion is not detectable for most of people, which makes sense to perform video adaptation. The work presented in this thesis is supposed to help improving the design of self adaptive video streaming services that can deliver video content independently of network technology and end-device capability while seeking the best possible experience for video. / Ardendo småföretagsdoktorand

Over the past 10 years online video streaming has seen a tremendous increase in popularity, as it has become a great source of both entertainment and education. This increase in popularity has led to demands for higher quality streams, shorter buffering time and service adaptivity, based on the user’s personal prerequisites. These demands together with a constant increase in Internet usage have posed several challenges for streaming service providers to overcome. Within this master thesis an exploratory research and development project has been conducted. The project’s purpose has been to investigate common approaches, standards and trends related to establishing a multimedia streaming service. Based on the results from these investigations, the purpose has furthermore been to design and implement a proof-of-concept streaming server fulfilling the thesis internship company’s needs and requirements. Research has concluded that there are at least five vital components, which have to be carefully considered in order to establish a successful streaming service. These vital components are; the service system structure, the service application programming interface (API), the service hosting solution, the service data storage solution and finally the actual streaming module. Based on results from conducted investigations of common design approaches for each vital component, decisions for the thesis project implementation have been made. The resulting system has been built using the event-based system structure framework Node.js. A representational state transfer (REST) API has furthermore been implemented for managing client request routing. The resulting system has been implemented on a self-hosted server solution even though this is neither a preferred choice in theory nor common practice. The decision has however been made due to future plans at the thesis internship company of investing in a corporate-wide cloud-based server solution. For the service data storage solution the relation-based database management system MySQL has been implemented. For the final recognized vital component, the streaming module, support for HTTP-based multimedia streams has been implemented. This choice of technique has been made due to the many benefits brought on by using HTTP, such as cost efficiency and bandwidth optimization. The use of HTTP is also currently a trending choice of technique Thesis for Master’s Degree at HIT and LiU within the streaming community due to the recently published standard MPEG-DASH.

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Nowadays the World Wide Web increasingly provides rich multimedia contents to its users.In order to further enhance the experience of web-users, researchers have sought solutions to integrate yet another modality into the web experience by augmenting web content with haptic properties. In those applications, users are able to interact with web virtual environments (such as games and e-learning systems) enriched with haptic contents. However, it is not easy for designers without pro cient web programming background and basic knowledge regarding haptics, to develop a web application with haptic content enabled. Additionally, there is currently no standard to describe and reuse a well-described haptic application which can be played in web browsers. In this thesis, I present an MPEG-V based authoring tool for facilitating the development procedure of haptics-enabled web applications. The system provides an interface for users to create their own application, add custom 3D models, and modify their graphic and haptic properties. Haptic properties include the speci cation of collision detection mechanism and object surface properties which in turn directly a ect the force simulations. Finally, the user is able to export a haptic-enabled 3D scene in a standard MPEG-V format which can be reconstructed in a web haptic player. A detailed experiment is conducted to evaluate the force simulations, application development process and design of user interface. The results not only verify my proposed methodology, but also show the high acceptance level by users with all levels of programming knowledge of the system.

The subject of this term project is the analysis and description of possibilities in video streaming optimization, and the design of a client/server application to implement optimized video streaming in practice. The client side of the application is realized with a mobileapplication for the Android platform, which in addition to video streaming implements the functionality of a file manager over directories and files saved in the cloud.

The topic of the master's thesis is about transmission of multimedia via network with help of compression’s algorithm used in codec MPEG-4 part 10 and Real Time Protocol (RTP). First part of this master thesis will be familiarization with basic terms about multimedia. It will be queried about techniques of compression axioms for audio and video, justification for necessary use of compression in transmitting multimedia via network. Also, here will be subscribed principles and properties of Real Time Protocol, which was designed for multimedia stream. From the start, competent codec for implementation of two applications (client, server) with read raw video and audio data, will choose the following : compression with help of codec Theora (Vorbis), transfer via network in RTP packets, decode and play at visual form for end user. Complete subscription of implementation for both applications written in programming languages C/C++ and Java, will be certain. The basic overview about this problematic experience with implementation, which were here concluded, are the reasons for reading this master thesis.

Key tasks of this work are to create the simulation of a wireless network in ns-3 and to stream a video over this network by using MPEG-DASH technology. It describes the tools and methods how to encode a video according to MPEG-DASH. It is explained what is needed to run video server, which uses MPEG-DASH technology to stream videos. Then, it is described how a simulation of wired and wireless WiFi and LTE networks is created. The simulation starts a server and shows how it works, how many nodes can be used and chooses suitable segment duration.

The Internet today is experiencing a large growth in the amount of traffic due to the number of users consuming streaming media. For both the operator and content providers, streaming of media generates most of its revenue through advertisements inserted in the content. One common approach is to pre-stitched (i.e. insert) advertisements into the content. Another approach is dynamic advertisement insertion, which inserts advertisements at run-time while the media is being streamed. Dynamic advertisement insertion gives operators the flexibility to insert advertisements based on context, such as the user's geographic location or the user's preferences. Developing a technique to successfully insert advertisements dynamically into the streaming media has several challenges, such as maintaining synchronization of the media, choosing the appropriate transport format for media delivery, and finding a splicing boundary that starts with a key frame. The details of these challenges are detailed in this thesis. We carried out extensive research to find the best transport format for delivery of media and we studied prior work in an effort to find an appropriate streaming solution to perform dynamic advertisement insertion. Based upon this research and our study of prior work we identify the best transport format for delivery of media chunks, then propose, implement, and evaluate a technique for advertisement insertion. / Idag har internet mycket trafik på grund av att alltfler servrar erbjuder högkvalitativa videon som strömmas till internetanvändare. Både för operatörer och leverantörer av sådan innehåll genererar direktuppspelning mest intäkter genom annonser som lagts till i videon. Det är väldigt vanligt att lägga till annonser i videon genom att sy in dem i videofiler. En annan metod är att lägga till annonser dynamiskt. Det betyder att resulterande videofilen genereras medan den blir strömmad till användare. Att sätta in annonser dynamiskt har som fördel för operatörer att välja reklam beroende på kontexten, såsom användarens position eller preferenser. Det är utmanande att utveckla den teknik som krävs för att kunna sätta in annonser dynamiskt i strömmade videofiler. Till exempel är det viktigt att tänka på följande: synkronisering av strömmad innehåll, val av lämplig transportformat för videoleveransen och gränsen för skarvning (så kallad splicing boundary). Detaljerna kring denna teknik finns i denna avhandling. Vi har forskat på att hitta det bästa transportformatet för videoleverans och vi har studerat relevant arbete som gjorts tidigare för att hitta en lämplig mekanism för dynamisk annonsinsättning. Baserat på vår forskning och studerande av tidigare arbeten har vi klassificerat det bästa formatet för leveransen av videostycken, implementerat och evaluerat en teknik för annonsinlägg.

As video applications become more diverse, video must be adapted in different ways to meet the requirements of different applications when there are insufficient resources. In this dissertation, we address two sorts of requirements that cannot be addressed by existing video adaptation technologies: (i) accommodating large variations in resolution and (ii) collecting video effectively in a multi-hop sensor network. In addition, we also address requirements for implementing video adaptation in a sensor network. Accommodating large variation in resolution is required by the existence of display devices with widely disparate screen sizes. Existing resolution adaptation technologies usually aim at adapting video between two resolutions. We examine the limitations of these technologies that prevent them from supporting a large number of resolutions efficiently. We propose several hybrid schemes and study their performance. Among these hybrid schemes, Bonneville, a framework that combines multiple encodings with limited scalability, can make good trade-offs when organizing compressed video to support a wide range of resolutions. Video collection in a sensor network requires adapting video in a multi-hop storeand- forward network and with multiple video sources. This task cannot be supported effectively by existing adaptation technologies, which are designed for real-time streaming applications from a single source over IP-style end-to-end connections. We propose to adapt video in the network instead of at the network edge. We also propose a framework, Steens, to compose adaptation mechanisms on multiple nodes. We design two signaling protocols in Steens to coordinate multiple nodes. Our simulations show that in-network adaptation can use buffer space on intermediate nodes for adaptation and achieve better video quality than conventional network-edge adaptation. Our simulations also show that explicit collaboration among multiple nodes through signaling can improve video quality, waste less bandwidth, and maintain bandwidth-sharing fairness. The implementation of video adaptation in a sensor network requires system support for programmability, retaskability, and high performance. We propose Cascades, a component-based framework, to provide the required support. A prototype implementation of Steens in this framework shows that the performance overhead is less than 5% compared to a hard-coded C implementation.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第19138号 / 情博第584号 / 新制||情||102(附属図書館) / 32089 / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 佐藤 高史, 教授 小野寺 秀俊, 教授 髙木 直史 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM