15 research outputs found
STANDARDIZED TOOLCHAIN AND MODEL DEVELOPMENT FOR VIDEO QUALITY ASSESSMENT - THE MISSION OF THE JOINT EFFORT GROUP IN VQEG
International audienceSince 1997, the Video Quality Experts Group (VQEG) has been active in the field of subjective and objective video quality assessment. The group has validated competitive quality metrics throughout several projects. Each of these projects requires mandatory actions such as creating a testplan and obtaining databases consisting of degraded video sequences with corresponding subjective quality ratings. Recently, VQEG started a new open initiative, the Joint Effort Group (JEG), for encouraging joint collaboration on all mandatory actions needed to validate video quality metrics. Within the JEG, effort is made to advance the field of both subjective and objective video quality measurement by providing proper software tools and subjective databases to the community. One of the subprojects of the JEG is the joint development of a hybrid H.264/AVC objective quality metric. In this paper, we introduce the JEG and provide an overview of the different ongoing activities within this newly started group
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 großen
Herausforderungen jeder Neuentwicklung im Bereich der Multimediasysteme.
Doch proportional zur technischen Komplexität 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 Qualitätsbewertung
durchgeführt. Deren Ziel über den gesamten Entwcklungsprozesses ist es, die
kritischen Komponenten des Systems mit so wenig wie möglich wahrnehmbarem
Einfluss auf diewahrgenommene Qualität des Nutzers zu optimieren. Bereits
seit den 1970er Jahren werden hierfür Leitfäden verschiedener
Standardisierungsgremien zur Verfügung gestellt, in denen unterschiedliche
Evaluationsmethoden definiert sind, um die wahrgenommene Gesamtqualität des
Systems mit Hilfe von Skalen quantitativ evaluieren zu können. Aktuelle
Ansätze erweitern diese klassische Methoden um Sichtweise, die über die
klassische Evaluation hedonistischer Gesamtqualität hinausgehen, um das
Wissen über individuell zugrundeliegende Qualitätsfaktoren 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
Verknüpfung hedonistischer Qualität und zugrundeliegender Qualitätsfaktoren
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
Gesamtqualität und deskriptive, sensorische Analyse zur Erhebung
individueller Qualitätsfaktoren. Die Methode ist für Erhebungen mit naiven
Probanden geeignet. OPQ wurde unter besonderer Beachtung von Validität und
Reliabilität in einem konstruktivem Ansatz entwickelt und in einer Folge
von Studien während der Entwicklung eines mobilem 3DTV-Systems mit über 300
Probanden angewendet. Die Ergebnisse dieser Studien unterstreichen die sich
ergänzenden Ergebnisse quantitativer und sensorischer Analysen.Neben der
Entwicklung von OPQ werden in der vorliegenden Arbeit weitere Ansätze
sensorischer Analyse präsentiert und miteinander verglichen. Gerade dieser
Vergleich ist ein wichtiger Bestandteil der Validierung der OPQ-Methode. Um
die Stärken und Schwächen jeder Methode ganzheitlich erfassen und
vergleichen zu können, wurde hierfür ein Methodenvergleichsmodell
entwickelt und operationalisiert, das den methodischen Beitrag der Arbeit
vervollständigtTo 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
No-Reference Video Quality Assessment Model for Distortion Caused by Packet Loss in the Real-Time Mobile Video Services
Packet loss will make severe errors due to the corruption of related video data. For most video streams, because the predictive coding structures are employed, the transmission errors in one frame will not only cause decoding failure of itself at the receiver side, but also propagate to its subsequent frames along the motion prediction path, which will bring a significant degradation of end-to-end video quality. To quantify the effects of packet loss on video quality, a no-reference objective quality assessment model is presented in this paper. Considering the fact that the degradation of video quality significantly relies on the video content, the temporal complexity is estimated to reflect the varying characteristic of video content, using the macroblocks with different motion activities in each frame. Then, the quality of the frame affected by the reference frame loss, by error propagation, or by both of them is evaluated, respectively. Utilizing a two-level temporal pooling scheme, the video quality is finally obtained. Extensive experimental results show that the video quality estimated by the proposed method matches well with the subjective quality
Video Quality Prediction for Video over Wireless Access Networks (UMTS and WLAN)
Transmission of video content over wireless access networks (in particular, Wireless Local
Area Networks (WLAN) and Third Generation Universal Mobile Telecommunication System (3G UMTS)) is growing exponentially and gaining popularity, and is predicted to expose new revenue streams for mobile network operators. However, the success of these video applications over wireless access networks very much depend on meeting the user’s Quality of Service (QoS) requirements. Thus, it is highly desirable to be able to predict and, if appropriate, to control video quality to meet user’s QoS requirements. Video quality is
affected by distortions caused by the encoder and the wireless access network. The impact of these distortions is content dependent, but this feature has not been widely used in existing
video quality prediction models.
The main aim of the project is the development of novel and efficient models for video
quality prediction in a non-intrusive way for low bitrate and resolution videos and to
demonstrate their application in QoS-driven adaptation schemes for mobile video streaming
applications. This led to five main contributions of the thesis as follows:(1) A thorough understanding of the relationships between video quality, wireless access network (UMTS and WLAN) parameters (e.g. packet/block loss, mean burst length
and link bandwidth), encoder parameters (e.g. sender bitrate, frame rate) and content type is provided. An understanding of the relationships and interactions between them
and their impact on video quality is important as it provides a basis for the development of non-intrusive video quality prediction models.(2) A new content classification method was proposed based on statistical tools as content
type was found to be the most important parameter.
(3) Efficient regression-based and artificial neural network-based learning models were
developed for video quality prediction over WLAN and UMTS access networks. The
models are light weight (can be implemented in real time monitoring), provide a measure for user perceived quality, without time consuming subjective tests. The models have potential applications in several other areas, including QoS control and
optimization in network planning and content provisioning for network/service
providers.(4) The applications of the proposed regression-based models were investigated in (i)
optimization of content provisioning and network resource utilization and (ii) A new
fuzzy sender bitrate adaptation scheme was presented at the sender side over WLAN and UMTS access networks.
(5) Finally, Internet-based subjective tests that captured distortions caused by the encoder
and the wireless access network for different types of contents were designed. The
database of subjective results has been made available to research community as there is a lack of subjective video quality assessment databases.Partially sponsored by EU FP7 ADAMANTIUM Project (EU Contract 214751
The Impact of Multichannel Game Audio on the Quality of Player Experience and In-game Performance
Multichannel audio is a term used in reference to a collection of techniques designed to present sound to a listener from all directions. This can be done either over a collection of loudspeakers surrounding the listener, or over a pair of headphones by virtualising sound sources at specific positions. The most popular commercial example is surround-sound, a technique whereby sounds that make up an auditory scene are divided among a defined group of audio channels and played back over an array of loudspeakers. Interactive video games are well suited to this kind of audio presentation, due to the way in which in-game sounds react dynamically to player actions. Employing multichannel game audio gives the potential of immersive and enveloping soundscapes whilst also adding possible tactical advantages. However, it is unclear as to whether these factors actually impact a player’s overall experience. There is a general consensus in the wider gaming community that surround-sound audio is beneficial for gameplay but there is very little academic work to back this up. It is therefore important to investigate empirically how players react to multichannel game audio, and hence the main motivation for this thesis. The aim was to find if a surround-sound system can outperform other systems with fewer audio channels (like mono and stereo). This was done by performing listening tests that assessed the perceived spatial sound quality and preferences towards some commonly used multichannel systems for game audio playback over both loudspeakers and headphones. There was also a focus on how multichannel audio might influence the success of a player in a game, based on their in-game score and their navigation within a virtual world. Results suggest that surround-sound game audio is preferable over more regularly used two-channel stereo systems, because it is perceived to have higher spatial sound quality and there is an improvement in player performance. This illustrates the potential for multichannel game audio as a tool to positively influence player experiences, a core goal many game designers strive to achieve
Indicator Of Experince For Mobile Data Networks
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013Bu çalışmada mobil veri şebekeleri için kullanıcıların yaşadıkları deneyim kalitesini ölçmek adına farklı bir metod önerilmektedir. Literatürde önerilen yöntemler ağırlıklı olarak kullanıcıların deneyimlerine ilişkin görüşlerinin anketler düzenlenerek alınması veya mobil cihazlara yerleştirilen akıllı yazılımlar ile deneyimlerin ölçülmesi şeklindedir. Bu sebeple yapılan çalışmalar örnek küme üzerinden deneyimin bütüne aitmiş gibi konumlandırılması esasına dayanmaktadır. Bu çalışmada bahsedilen yöntemlerden farklı olarak mobil şebekede bulunan sistemsel istatistiklerin kullanılması ve radyo şebekesinin deneyime etkisini hesaplayan bir modelin önerilmesiyle farklı bir hesaplama yöntemi önerilmektedir. Bu sayede sadece belli bir örnek küme değil, servisi deneyimleyen tüm kullanıcılar için bir sonuç elde etmek mümkün olmaktadır. Bu amaçla IoE kısaltması adı altında mobil veri servisleri kullanımlarında deneyimin başarısı ölçülebilir ve hesaplanabilir bir parametre ile ifade edilmiştir.In this study, introducing a new way of quality of experience calculation methodology is aimed. A new parameter, indicator of experience (IoE) has been introduced, which is a combination of quantised throughput and acceptability of the user for mobile internet service. Most QoE calculations use mobile client or user perception researches. Differently, network level statistics and radio network modeling is used to calculate IoE. This new approach is then compared with mobile client measurements in order to prove the usability of the approach.Yüksek LisansM.Sc