18 research outputs found
Subjective Evaluation of Audiovisual Signals
This paper deals with subjective evaluation of audiovisual signals, with emphasis on the interaction between acoustic and visual quality. The subjective test is realized by a simple rating method. The audiovisual signal used in this test is a combination of images compressed by JPEG compression codec and sound samples compressed by MPEG-1 Layer III. Images and sounds have various contents. It simulates a real situation when the subject listens to compressed music and watches compressed pictures without the access to original, i.e. uncompressed signals
Video quality evaluation in IP videoconference between fixed and mobile devices
The integration of the mobile network with the fixed network, by using IP, has allowed the appearance of packet-based videoconference between fixed and mobile devices. Current mobile IP networks are sized for http traffic and its behavior is best-effort. In this context, it becomes compulsory to evaluate and measure the video quality when packets are transmitted through these networks. By doing this, results obtained could be used to size future networks and/or define different Quality of Service politics in future IMS networks. The objective of this final career project is to evaluate possible video quality degradation in videoconference applications through IP integrated network (fixed + mobile). A study of the currently available video quality evaluation tools will be made and, as well, a specific system for the video quality evaluation in communications between the IP fixed network and the 3.5G IP mobile network, using own methodology, will be developed. Several evaluation scenarios will be defined, with different mobile â fixed network configurations in order to identify the elements susceptible of degradate the quality of the video. The developed system must be able to process the video sequences in origin and in reception, so it will be a referential system
Understanding user experience of mobile video: Framework, measurement, and optimization
Since users have become the focus of product/service design in last decade, the term User eXperience (UX) has been frequently used in the field of Human-Computer-Interaction (HCI). Research on UX facilitates a better understanding of the various aspects of the userâs interaction with the product or service. Mobile video, as a new and promising service and research field, has attracted great attention. Due to the significance of UX in the success of mobile video (Jordan, 2002), many researchers have centered on this area, examining usersâ expectations, motivations, requirements, and usage context. As a result, many influencing factors have been explored (Buchinger, Kriglstein, Brandt & Hlavacs, 2011; Buchinger, Kriglstein & Hlavacs, 2009). However, a general framework for specific mobile video service is lacking for structuring such a great number of factors. To measure user experience of multimedia services such as mobile video, quality of experience (QoE) has recently become a prominent concept. In contrast to the traditionally used concept quality of service (QoS), QoE not only involves objectively measuring the delivered service but also takes into account userâs needs and desires when using the service, emphasizing the userâs overall acceptability on the service. Many QoE metrics are able to estimate the user perceived quality or acceptability of mobile video, but may be not enough accurate for the overall UX prediction due to the complexity of UX. Only a few frameworks of QoE have addressed more aspects of UX for mobile multimedia applications but need be transformed into practical measures. The challenge of optimizing UX remains adaptations to the resource constrains (e.g., network conditions, mobile device capabilities, and heterogeneous usage contexts) as well as meeting complicated user requirements (e.g., usage purposes and personal preferences). In this chapter, we investigate the existing important UX frameworks, compare their similarities and discuss some important features that fit in the mobile video service. Based on the previous research, we propose a simple UX framework for mobile video application by mapping a variety of influencing factors of UX upon a typical mobile video delivery system. Each component and its factors are explored with comprehensive literature reviews. The proposed framework may benefit in user-centred design of mobile video through taking a complete consideration of UX influences and in improvement of mobile videoservice quality by adjusting the values of certain factors to produce a positive user experience. It may also facilitate relative research in the way of locating important issues to study, clarifying research scopes, and setting up proper study procedures. We then review a great deal of research on UX measurement, including QoE metrics and QoE frameworks of mobile multimedia. Finally, we discuss how to achieve an optimal quality of user experience by focusing on the issues of various aspects of UX of mobile video. In the conclusion, we suggest some open issues for future study
Analysing and quantifying visual experience in medical imaging
Healthcare professionals increasingly view medical images and videos in a variety of environments. The perception and interpretation of medical visual information across all specialties, career stages, and practice settings are critical to patient care and safety. However, medical images and videos are not self-explanatory and thus need to be interpreted by humans, who are prone to errors caused by the inherent limitations of the human visual system. It is essential to understand how medical experts perceive visual content, and use this knowledge to develop new solutions to improve clinical practice. Progress has been made in the literature towards such understanding, however studies remain limited.
This thesis investigates two aspects of human visual experience in medical imaging, i.e., visual quality assessment and visual attention. Visual quality assessment is important as diverse visual signal distortion may arise in medical imaging and affect the perceptual quality of visual content, and therefore potentially impact the diagnosis accuracy. We adapted existing qualitative and quantitative methods to evaluate the quality of distorted medical videos. We also analysed the impact of medical specialty on visual perception and found significant differences between specialty groups, e.g., sonographers were in general more bothered by visual distortions than radiologists. Visual attention has been studied in medical imaging using eye-tracking technology. In this thesis, we firstly investigated gaze allocation with radiologists analysing two-view mammograms and secondly assessed the impact of expertise and experience on gaze behaviour. We also evaluated to what extent state-of-the-art visual attention models can predict radiologistsâ gaze behaviour and showed the limitations of existing models.
This thesis provides new experimental designs and statistical processes to evaluate the perception of medical images and videos, which can be used to optimise the visual experience of image readers in clinical practice
Evaluation of the MDC and FEC over the quality of service and quality of experience for video distribution in ad hoc networks
Mobile ad hoc networks (MANETs) offer an excellent scenario for deploying communication applications because of the connectivity and versatility of this kind of networks. In contrast, the topology is usually extremely dynamic causing high rate of packet loss, so that ensuring a specific Quality of Service (QoS) for real-time video services becomes a hard challenge. In this paper, we evaluate the effect of using Multiple Description Coding (MDC) and Forward Error Correction (FEC) techniques for improving video quality in a multimedia content distribution system. A hybrid architecture using fixed and wireless ad hoc networks is proposed, which enables the use of multipoint-to-point transmission. MDC and FEC mechanisms can be combined with multipath transmission to increase the network efficiency and recover lost packets, improving the overall Quality of Experience (QoE) of the receiver. Simulations have been analyzed paying attention to objective parameters (Peak Signal to Noise Ratio, Packet Delivery Ratio, Decodable Frame Rate and interruptions) and subjective parameters. Results show that MDC increases the probability of packet delivery and FEC is able to recover lost frames and reduce video interruptions in moderate mobility scenarios, resulting in the improvement of video quality and the final user experience.This work was supported by project MIQUEL (TEC2007- 68119-C02-01/TCM) of the Spanish Ministry of Education and Science. The authors would like to thank the Editor and the reviewers for helpful suggestions to improve the quality of this paper.Acelas Delgado, P.; Arce Vila, P.; Guerri Cebollada, JC.; Castellanos HernĂĄndez, WE. (2014). Evaluation of the MDC and FEC over the quality of service and quality of experience for video distribution in ad hoc networks. Multimedia Tools and Applications. 68(3):969-989. https://doi.org/10.1007/s11042-012-1111-3969989683Apostolopoulos JG, Wong T, Tan W, Wee SJ (2002) On multiple description streaming with content delivery networks. IEEE INFOCOMBoukerche A (2009) Algorithms and protocols for wireless and mobile ad hoc networks. John Wiley & Sons IncChow CO, Ishii H (2007) Enhancing real-time video streaming over mobile ad hoc networks using multipoint-to-point communication. Comput Commun 30:1754â1764Clausen T, Jacquet P (2003) Optimized link state routing protocol (OLSR), RFC 3626Corrie B et al (2003) Towards quality of experience in advanced collaborative environments. Third Annual Workshop on Advanced Collaborative EnvironmentsGabrielyan E, Hersch R (2006) Reliable multi-path routing schemes for real-time streaming. International Conference on Digital Telecommunications, pp 65â65Gandikota VR, Tamma BR, Murthy CSR (2008) Adaptive-FEC based packet loss resilience scheme for supporting voice communication over adhoc wireless networks. IEEE Trans Mobile Comput 7:1184â1199Gharavi H (2008) Multi-channel for multihop communication links. International Conference on Telecommunications, pp 1â6Grega M, Janowski L, Leszczuk M, Romaniak P, Papir Z (2008) Quality of experience evaluation for multimedia services. PrzeglÄ
d Telekomunikacyjny i WiadomoĆci Telekomunikacyjne 4:142â153Hsieh MY, Huang YM, Chian TC (2007) Transmission of layered video streaming via multi-path on ad hoc networks. Multimed Tool Appl 34:155â177ITUâInternational Telecommunication Union (2007) Definition of quality of experience (QoE)â, Reference: TD 109rev2 (PLEN/12)ITU-R Recommendation BT.500-12 (2009) Methodology for the subjective assessment of the quality of television pictures. International Telecommunication Union, GenevaITU-T Recommendation P.910 (2000) Subjective video quality assessment methods for multimedia applications. International Telecommunication Union, GenevaKao KL, Ke ChH, Shieh CH (2006) An advanced simulation tool-set for video transmission performance evaluation. IEEE Region 10 Conference, pp 1â40Ke CH et al (2006) A novel realistic simulation tool for video transmission over wireless network. Proceedings of the IEEE International Conference on Sensor Networks, Ubiquitous, and Trsutworthy ComputingKeisuke U, Cheeonn C, Hiroshi I (2008) A study on video performance of multipoint-to-point video streaming with multiple description coding over ad hoc networks. EEJ Trans Electron, Inf Syst 128:1431â1437Kilkki K (2008) Quality of experience in communications ecosystem. J Univers Comput Sci 14:615â624Li A (2007) RTP payload format for generic forward error correction. RFC 5109, Dec. 2007Li J, Blake C, Couto DD, Lee H, Morris R (2001) Capacity of ad hoc wireless networks. 7th Annual International Conference on Mobile Computing and Networking, pp 16â21Liao Y, Gibson JD (2011) Routing-aware multiple description video coding over mobile ad-hoc networks. IEEE Trans Multimed 13:132â142Lindeberg M, Kristiansen S, Plagemann T, Goebel V (2011) Challenges and techniques for video streaming over mobile ad hoc networks. Multimed Syst 17:51â82Mao S et al (2003) Video transport over ad hoc networks: multistream coding with multipath transport. IEEE J Sel Area Comm 21:1721â1737Ni P (2009) Towards Optimal Quality of Experience Via Scalable Video Coding. MĂ€lardalen University Press Licentiate Theses, SwedenPinson MH, Wolf S (2004) A new standardized method for objectively measuring video quality. IEEE Trans Broadcast 50:312â322Rong B, Qian Y, Lu K, Hu RQ, Kadoch M (2010) Multipath routing over wireless mesh networks for multiple description video transmission. IEEE J Sel Area Comm 28:321â331Schierl T, Ganger K, Hellge C, Wiegand T, Stockhammer T (2006) SVC-based multisource streaming for robust video trans- mission in mobile ad hoc networks. IEEE Wireless Comm 13:96â103Schierl T, Stockhammer T, Wiegand T (2007) Mobile video transmission using scalable video coding. IEEE Trans Circ Syst Video Tech 17:1204â1217Schwarz H, Marpe D, Wiegand T (2007) Overview of the scalable video coding extension of the H.264/AVC standard. IEEE Trans Circ Syst Video Tech 17:1103â1120VQEG (2008) Video quality experts group. Available online: http://www.vqeg.orgWang Z et al (2004) Image quality assessment: from error visibility to structural similarity. IEEE Trans Image Process 13:600â612Wei W, Zakhor A (2004) Robust multipath source routing protocol (RMPSR) for video communication over wireless ad hoc net- works. Proceedings of IEEE International Conference on Multimedia and Expo 2:1379â1382Winkler S, Mohandas P (2008) The evolution of video quality measurement: from PSNR to hybrid metrics. IEEE Trans Broadcast 54:660â668Xunqi Y, Modestino JW, Bajic IV (2005) Performance analysis of the efficacy of packet-level FEC in improving video transport over networks. IEEE International Conference on Image Processing 2:177â180Zink M, Schmitt J, Steinmetz R (2005) Layer-encoded video in scalable adaptive streaming. IEEE Trans Multimed 7:75â8
Analyse intelligente de la qualité d'expérience (QoE) dans les réseaux de diffusion de contenu web et mutimédia
Today user experience is becoming a reliable indicator for service providers and telecommunication operators to convey overall end to end system functioning. Moreover, to compete for a prominent market share, different network operators and service providers should retain and increase the customersâ subscription. To fulfil these requirements they require an efficient Quality of Experience (QoE) monitoring and estimation. However, QoE is a subjective metric and its evaluation is expensive and time consuming since it requires human participation. Therefore, there is a need for an objective tool that can measure the QoE objectively with reasonable accuracy in real-Time. As a first contribution, we analyzed the impact of network conditions on Video on Demand (VoD) services. We also proposed an objective QoE estimation tool that uses fuzzy expert system to estimate QoE from network layer QoS parameters. As a second contribution, we analyzed the impact of MAC layer QoS parameters on VoD services over IEEE 802.11n wireless networks. We also proposed an objective QoE estimation tool that uses random neural network to estimate QoE from the MAC layer perspective. As our third contribution, we analyzed the effect of different adaption scenarios on QoE of adaptive bit rate streaming. We also developed a web based subjective test platform that can be easily integrated in a crowdsourcing platform for performing subjective tests. As our fourth contribution, we analyzed the impact of different web QoS parameters on web service QoE. We also proposed a novel machine learning algorithm i.e. fuzzy rough hybrid expert system for estimating web service QoE objectivelyDe nos jours, lâexpĂ©rience de l'utilisateur appelĂ© en anglais « User Experience » est devenue lâun des indicateurs les plus pertinents pour les fournisseurs de services ainsi que pour les opĂ©rateurs de tĂ©lĂ©communication pour analyser le fonctionnement de bout en bout de leurs systĂšmes (du terminal client, en passant par le rĂ©seaux jusquâĂ lâinfrastructure des services etc.). De plus, afin dâentretenir leur part de marchĂ© et rester compĂ©titif, les diffĂ©rents opĂ©rateurs de tĂ©lĂ©communication et les fournisseurs de services doivent constamment conserver et accroĂźtre le nombre de souscription des clients. Pour rĂ©pondre Ă ces exigences, ils doivent disposer de solutions efficaces de monitoring et dâestimation de la qualitĂ© d'expĂ©rience (QoE) afin dâĂ©valuer la satisfaction de leur clients. Cependant, la QoE est une mesure qui reste subjective et son Ă©valuation est coĂ»teuse et fastidieuse car elle nĂ©cessite une forte participation humaine (appelĂ© panel de dâĂ©valuation). Par consĂ©quent, la conception dâun outil qui peut mesurer objectivement cette qualitĂ© d'expĂ©rience avec une prĂ©cision raisonnable et en temps rĂ©el est devenue un besoin primordial qui constitue un challenge intĂ©ressant Ă rĂ©soudre. Comme une premiĂšre contribution, nous avons analysĂ© l'impact du comportement dâun rĂ©seau sur la qualitĂ© des services de vidĂ©o Ă la demande (VOD). Nous avons Ă©galement proposĂ© un outil d'estimation objective de la QoE qui utilise le systĂšme expert basĂ© sur la logique floue pour Ă©valuer la QoE Ă partir des paramĂštres de qualitĂ© de service de la couche rĂ©seau. Dans une deuxiĂšme contribution, nous avons analysĂ© l'impact des paramĂštres QoS de couche MAC sur les services de VoD dans le cadre des rĂ©seaux sans fil IEEE 802.11n. Nous avons Ă©galement proposĂ© un outil d'estimation objective de la QoE qui utilise le rĂ©seau alĂ©atoire de neurones pour estimer la QoE dans la perspective de la couche MAC. Pour notre troisiĂšme contribution, nous avons analysĂ© l'effet de diffĂ©rents scĂ©narios d'adaptation sur la QoE dans le cadre du streaming adaptatif au dĂ©bit. Nous avons Ă©galement dĂ©veloppĂ© une plate-Forme Web de test subjectif qui peut ĂȘtre facilement intĂ©grĂ© dans une plate-Forme de crowd-Sourcing pour effectuer des tests subjectifs. Finalement, pour notre quatriĂšme contribution, nous avons analysĂ© l'impact des diffĂ©rents paramĂštres de qualitĂ© de service Web sur leur QoE. Nous avons Ă©galement proposĂ© un algorithme d'apprentissage automatique i.e. un systĂšme expert hybride rugueux basĂ© sur la logique floue pour estimer objectivement la QoE des Web service
Open Profiling of Quality: A Mixed Methods Research Approach for Audiovisual Quality Evaluations
Den Anforderungen der Konsumenten gerecht zu werden und ihnen eine immer
besser werdende Quality of Experience zu bieten, ist eine der groĂen
Herausforderungen jeder Neuentwicklung im Bereich der Multimediasysteme.
Doch proportional zur technischen KomplexitÀt neuer Systeme, in denen
Komponenten unterschiedlicher Technologien zu neuen System wie zum Beispiel
mobilem 3D-Fernsehen verschmolzen werden, steigt auch die Frage, wie eine
optimierte Quality of Experience eigentlich zu erreichen ist. Daher werden
seit langer Zeit Nutzertests zur subjektiven QualitÀtsbewertung
durchgefĂŒhrt. Deren Ziel ĂŒber den gesamten Entwcklungsprozesses ist es, die
kritischen Komponenten des Systems mit so wenig wie möglich wahrnehmbarem
Einfluss auf diewahrgenommene QualitÀt des Nutzers zu optimieren. Bereits
seit den 1970er Jahren werden hierfĂŒr LeitfĂ€den verschiedener
Standardisierungsgremien zur VerfĂŒgung gestellt, in denen unterschiedliche
Evaluationsmethoden definiert sind, um die wahrgenommene GesamtqualitÀt des
Systems mit Hilfe von Skalen quantitativ evaluieren zu können. Aktuelle
AnsĂ€tze erweitern diese klassische Methoden um Sichtweise, die ĂŒber die
klassische Evaluation hedonistischer GesamtqualitÀt hinausgehen, um das
Wissen ĂŒber individuell zugrundeliegende QualitĂ€tsfaktoren zu erweitern.Die
vorliegende Dissertation verfolgt dabei zwei Ziele. Zum einen soll eine
audiovisuelle Evaluationsmethode entwickelt werden, die eine kombinierte
Analyse quantitativer und qualitativer Daten ermöglicht, um eine
VerknĂŒpfung hedonistischer QualitĂ€t und zugrundeliegender QualitĂ€tsfaktoren
zu ermöglichen. Weiter soll diese Methode innerhalb des Gebiets der mobiler
3DTV-Systeme erprobt und validiert werden.Open Profiling of Quality (OPQ)
als Evaluationsmethode kombiniert quantitative Evaluation wahrgenommener
GesamtqualitÀt und deskriptive, sensorische Analyse zur Erhebung
individueller QualitĂ€tsfaktoren. Die Methode ist fĂŒr Erhebungen mit naiven
Probanden geeignet. OPQ wurde unter besonderer Beachtung von ValiditÀt und
ReliabilitÀt in einem konstruktivem Ansatz entwickelt und in einer Folge
von Studien wĂ€hrend der Entwicklung eines mobilem 3DTV-Systems mit ĂŒber 300
Probanden angewendet. Die Ergebnisse dieser Studien unterstreichen die sich
ergÀnzenden Ergebnisse quantitativer und sensorischer Analysen.Neben der
Entwicklung von OPQ werden in der vorliegenden Arbeit weitere AnsÀtze
sensorischer Analyse prÀsentiert und miteinander verglichen. Gerade dieser
Vergleich ist ein wichtiger Bestandteil der Validierung der OPQ-Methode. Um
die StÀrken und SchwÀchen jeder Methode ganzheitlich erfassen und
vergleichen zu können, wurde hierfĂŒr ein Methodenvergleichsmodell
entwickelt und operationalisiert, das den methodischen Beitrag der Arbeit
vervollstÀndigtTo meet the requirements of consumers and to provide them with a greater
quality of experience than existing systems do is a key issue for the
success of modern multimedia systems. However, the question about an
optimized quality of experience becomes more and more complex as
technological systems are evolving and several systems are merged into new
ones, e.g. systems for mobile 3D television and video. To be able to
optimize critical components of a system under development with as little
perceptual errors as possible, user studies are conducted throughout the
whole process. A variety of research methods for different purposes have
been provided by standardization bodies since the 1970s. These methods
allow researchers to evaluate the hedonic excellence of a set of test
stimuli. However, a broader view to quality has been taken recently to be
able to evaluate quality beyond its hedonic excellence to obtain a greater
knowledge about perceived quality and its subjective quality factors that
impact on the user.The goal of this thesis is twofold. The primary goal is
the development of a validated mixed methods research approach for
audiovisual quality evaluations. The method shall allow collecting
quantitative and descriptive data during the experiment to combine
evaluation of hedonic excellence and the elicitation of underlying
subjective quality factors. The second goal is the application of the
developed method within a series of studies in the domain of mobile 3D
video and television to show its applicability.Open Profiling of Quality
(OPQ) is a mixed-methods research approach which combines a quantitative,
psychoperceptual evaluation of hedonic excellence and a descriptive sensory
analysis of underlying quality factors based on naive participants'
individual vocabulary. This combination allows defining the excellence of
overall quality, understanding the characteristics of quality perception,
and, eventually, constructing a link between preferences and quality
attributes. The method was developed under constructive research with
respect to validity and reliability of test results. A series of quality
evaluation studies with more than 300 test participants was conducted along
different critical components of a system for optimized mobile 3DTV content
delivery over DVB-H.The results complemented each other, and, even more
importantly, quantitative quality preferences were explained by sensory
descriptions in all studies. Beyond the development of OPQ, the thesis
proposes further research approaches, e.g. a conventional profiling in
which OPQ's individual vacobulary is substituted by a fixed set of Quality
ofExperience components or Descriptive Sorted Napping which combines a
sorting task and a short post-task interview. All approaches are compared
to Open ProVling of Quality at the end of the thesis. To be able to
holistically contrast strengths and weaknesses of each method, a comparison
model for audiovisual evaluation methods was developed and a Vrst
conceptual operationalization of the model was applied in the comparison
Context-awareness for ubiquitous media service delivery in next generation networks
Les rĂ©centes avancĂ©es technologiques permettent dĂ©sormais la fabrication de terminaux mobiles de plus en plus compacts et dotĂ©s de plusieurs interfaces rĂ©seaux. Le nouveau modĂšle de consommation de mĂ©dias se rĂ©sume par le concept "Anytime, Anywhere, Any Device" et impose donc de nouvelles exigences en termes de dĂ©ploiement de services ubiquitaires. Cependant la conception et le developpement de rĂ©seaux ubiquitaires et convergents de nouvelles gĂ©nĂ©rations soulĂšvent un certain nombre de dĂ©fis techniques. Les standards actuels ainsi que les solutions commerciales pourraient ĂȘtre affectĂ©s par le manque de considĂ©ration du contexte utilisateur. Le ressenti de l'utilisateur concernant certains services multimĂ©dia tels que la VoIP et l'IPTV dĂ©pend fortement des capacitĂ©s du terminal et des conditions du rĂ©seau d'accĂšs. Cela incite les rĂ©seaux de nouvelles gĂ©nĂ©rations Ă fournir des services ubiquitaires adaptĂ©s Ă l'environnement de l'utilisateur optimisant par la mĂȘme occasion ses resources. L'IP Multimedia Subsystem (IMS) est une architecture de nouvelle gĂ©nĂ©ration qui centralise l'accĂšs aux services et permet la convergence des rĂ©seaux fixe/mobile. NĂ©anmoins, l'Ă©volution de l'IMS est nĂ©cessaire sur les points suivants :- l'introduction de la sensibilitĂ© au contexte utilisateur et de la PQoS (Perceived QoS) : L'architecture IMS ne prend pas en compte l'environnement de l'utilisateur, ses prĂ©fĂ©rences et ne dispose pas d'un mĂ©chanisme de gestion de PQOS. Pour s'assurer de la qualitĂ© fournit Ă l'utilisateur final, des informations sur l'environnement de l'utilisateur ainsi que ses prĂ©fĂ©rences doivent transiter en cĆur de rĂ©seau afin d'y ĂȘtre analysĂ©s. Ce traitement aboutit au lancement du service qui sera adaptĂ© et optimisĂ© aux conditions observĂ©es. De plus pour le service d'IPTV, les caractĂ©ristiques spatio-temporelles de la vidĂ©o influent de maniĂšre importante sur la PQoS observĂ©e cĂŽtĂ© utilisateur. L'adaptation des services multimĂ©dias en fonction de l'Ă©volution du contexte utilisateur et de la nature de la vidĂ©o diffusĂ©e assure une qualitĂ© d'expĂ©rience Ă l'utilisateur et optimise par la mĂȘme occasion l'utilisation des ressources en cĆur de rĂ©seau.- une solution de mobilitĂ© efficace pour les services conversationnels tels que la VoIP : Les derniĂšres publications 3GPP fournissent deux solutions de mobilitĂ©: le LTE proposeMIP comme solution de mobilitĂ© alors que l'IMS dĂ©finit une mobilitĂ© basĂ©e sur le protocoleapplicatif SIP. Ces standards dĂ©finissent le systĂšme de signalisation mais ne s'avancent pas sur la gestion du flux mĂ©dia lors du changement d'interface rĂ©seau. La deuxiĂšme section introduit une Ă©tude comparative dĂ©taillĂ©e des solutions de mobilitĂ© dans les NGNs.Notre premiĂšre contribution est la spĂ©cification de l'architecture globale de notre plateforme IMS sensible au contexte utilisateur rĂ©alisĂ©e au sein du projet EuropĂ©en ADAMANTIUM. Nous dĂ©taillons tout d'abord le serveur MCMS intelligent placĂ© dans la couche application de l'IMS. Cet Ă©lĂ©ment rĂ©colte les informations de qualitĂ© de services Ă diffĂ©rents Ă©quipements rĂ©seaux et prend la dĂ©cision d'une action sur l'un de ces Ă©quipements. Ensuite nous dĂ©finissons un profil utilisateur permettant de dĂ©crire son environnement et de le diffuser en coeur de rĂ©seau. Une Ă©tude sur la prĂ©diction de satisfaction utilisateur en fonction des paramĂštres spatio-temporels de la vidĂ©o a Ă©tĂ© rĂ©alisĂ©e afin de connaĂźtre le dĂ©bit idĂ©al pour une PQoS dĂ©sirĂ©e.Notre deuxiĂšme contribution est l'introduction d'une solution de mobilitĂ© adaptĂ©e aux services conversationnels (VoIP) tenant compte du contexte utilisateur. Notre solution s'intĂšgre Ă l'architecture IMS existante de façon transparente et permet de rĂ©duire le temps de latence du handover. Notre solution duplique les paquets de VoIP sur les deux interfaces actives pendant le temps de la transition. ParallĂšlement, un nouvel algorithme de gestion de mĂ©moire tampon amĂ©liore la qualitĂ© d'expĂ©rience pour le service de VoIP.The latest advances in technology have already defied Moore s law. Thanks to research and industry, hand-held devices are composed of high processing embedded systems enabling the consumption of high quality services. Furthermore, recent trends in communication drive users to consume media Anytime, Anywhere on Any Device via multiple wired and wireless network interfaces. This creates new demands for ubiquitous and high quality service provision management. However, defining and developing the next generation of ubiquitous and converged networks raise a number of challenges. Currently, telecommunication standards do not consider context-awareness aspects for network management and service provisioning. The experience felt by the end-user consuming for instance Voice over IP (VoIP) or Internet Protocol TeleVision (IPTV) services varies depending mainly on user preferences, device context and network resources. It is commonly held that Next Generation Network (NGN) should deliver personalized and effective ubiquitous services to the end user s Mobile Node (MN) while optimizing the network resources at the network operator side. IP Multimedia Subsystem (IMS) is a standardized NGN framework that unifies service access and allows fixed/mobile network convergence. Nevertheless IMS technology still suffers from a number of confining factors that are addressed in this thesis; amongst them are two main issues :The lack of context-awareness and Perceived-QoS (PQoS):-The existing IMS infrastructure does not take into account the environment of the user ,his preferences , and does not provide any PQoS aware management mechanism within its service provisioning control system. In order to ensure that the service satisfies the consumer, this information need to be sent to the core network for analysis. In order to maximize the end-user satisfaction while optimizing network resources, the combination of a user-centric network management and adaptive services according to the user s environment and network conditions are considered. Moreover, video content dynamics are also considered as they significantly impact on the deduced perceptual quality of IPTV services. -The lack of efficient mobility mechanism for conversational services like VoIP :The latest releases of Third Generation Partnership Project (3GPP) provide two types of mobility solutions. Long-Term Evolution (LTE) uses Mobile IP (MIP) and IMS uses Session Initiation Protocol (SIP) mobility. These standards are focusing on signaling but none of them define how the media should be scheduled in multi-homed devices. The second section introduces a detailed study of existing mobility solutions in NGNs. Our first contribution is the specification of the global context-aware IMS architecture proposed within the European project ADAptative Management of mediA distributioN based on saTisfaction orIented User Modeling (ADAMANTIUM). We introduce the innovative Multimedia Content Management System (MCMS) located in the application layer of IMS. This server combines the collected monitoring information from different network equipments with the data of the user profile and takes adaptation actions if necessary. Then, we introduce the User Profile (UP) management within the User Equipment (UE) describing the end-user s context and facilitating the diffusion of the end-user environment towards the IMS core network. In order to optimize the network usage, a PQoS prediction mechanism gives the optimal video bit-rate according to the video content dynamics. Our second contribution in this thesis is an efficient mobility solution for VoIP service within IMS using and taking advantage of user context. Our solution uses packet duplication on both active interfaces during handover process. In order to leverage this mechanism, a new jitter buffer algorithm is proposed at MN side to improve the user s quality of experience. Furthermore, our mobility solution integrates easily to the existing IMS platform.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF
No-reference video quality assessment model based on artifact metrics for digital transmission applications
Tese (doutorado)âUniversidade de BrasĂlia, Instituto de CiĂȘncias Exatas, Departamento de CiĂȘncia da Computação, 2017.Um dos principais fatores para a redução da qualidade do conteĂșdo visual, em sistemas de imagem digital, sĂŁo a presença de degradaçÔes introduzidas durante as etapas de processamento de sinais. Contudo, medir a qualidade de um vĂdeo implica em comparar direta ou indiretamente um vĂdeo de teste com o seu vĂdeo de referĂȘncia. Na maioria das aplicaçÔes, os seres humanos sĂŁo o meio mais confiĂĄvel de estimar a qualidade de um vĂdeo. Embora mais confiĂĄveis, estes mĂ©todos consomem tempo e sĂŁo difĂceis de incorporar em um serviço de controle de qualidade automatizado. Como alternativa, as mĂ©tricas objectivas, ou seja, algoritmos, sĂŁo geralmente usadas para estimar a qualidade de um vĂdeo automaticamente. Para desenvolver uma mĂ©trica objetiva Ă© importante entender como as caracterĂsticas perceptuais de um conjunto de artefatos estĂŁo relacionadas com suas forças fĂsicas e com o incĂŽmodo percebido. EntĂŁo, nĂłs estudamos as caracterĂsticas de diferentes tipos de artefatos comumente encontrados em vĂdeos comprimidos (ou seja, blocado, borrado e perda-de-pacotes) por meio de experimentos psicofĂsicos para medir independentemente a força e o incĂŽmodo desses artefatos, quando sozinhos ou combinados no vĂdeo. NĂłs analisamos os dados obtidos desses experimentos e propomos vĂĄrios modelos de qualidade baseados nas combinaçÔes das forças perceptuais de artefatos individuais e suas interaçÔes. Inspirados pelos resultados experimentos, nĂłs propomos uma mĂ©trica sem-referĂȘncia baseada em caracterĂsticas extraĂdas dos vĂdeos (por exemplo, informaçÔes DCT, a mĂ©dia da diferença absoluta entre blocos de uma imagem, variação da intensidade entre pixels vizinhos e atenção visual). Um modelo de regressĂŁo nĂŁo-linear baseado em vetores de suporte (Support Vector Regression) Ă© usado para combinar todas as caracterĂsticas e estimar a qualidade do vĂdeo. Nossa mĂ©trica teve um desempenho muito melhor que as mĂ©tricas de artefatos testadas e para algumas mĂ©tricas com-referĂȘncia (full-reference).The main causes for the reducing of visual quality in digital imaging systems are the unwanted presence of degradations introduced during processing and transmission steps. However, measuring the quality of a video implies in a direct or indirect comparison between test video and reference video. In most applications, psycho-physical experiments with human subjects are the most reliable means of determining the quality of a video. Although more reliable, these methods are time consuming and difficult to incorporate into an automated quality control service. As an alternative, objective metrics, i.e. algorithms, are generally used to estimate video quality quality automatically. To develop an objective metric, it is important understand how the perceptual characteristics of a set of artifacts are related to their physical strengths and to the perceived annoyance. Then, to study the characteristics of different types of artifacts commonly found in compressed videos (i.e. blockiness, blurriness, and packet-loss) we performed six psychophysical experiments to independently measure the strength and overall annoyance of these artifact signals when presented alone or in combination. We analyzed the data from these experiments and proposed several models for the overall annoyance based on combinations of the perceptual strengths of the individual artifact signals and their interactions. Inspired by experimental results, we proposed a no-reference video quality metric based in several features extracted from the videos (e.g. DCT information, cross-correlation of sub-sampled images, average absolute differences between block image pixels, intensity variation between neighbouring pixels, and visual attention). A non-linear regression model using a support vector (SVR) technique is used to combine all features to obtain an overall quality estimate. Our metric performed better than the tested artifact metrics and for some full-reference metrics