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  • 1.
    Allison, R.S.
    et al.
    York University, Canada.
    Brunnstrom, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Chandler, D.M.
    Shizuoka University, Japan.
    Colett, H.
    Intel Corp, USA.
    Corriveau, P.
    Intel Corp, USA.
    Daly, S.
    Dolby Laboratories Inc, USA.
    Goel, J.
    Qualcomm Technologies, USA.
    Long, J.Y.
    Intel Corp, USA.
    Wilcox, L.M.
    York University, Canada.
    Yaacob, Y.
    Shizuoka University, Japan.
    Yang, S. N.
    Pacific University, USA.
    Zhang, Y.
    Xi’an Jiaotong University, China.
    Perspectives on the definition of visually lossless quality for mobile and large format displays2018In: Journal of Electronic Imaging, ISSN 10179909, Vol. 27, no 5, article id 053035Article in journal (Refereed)
    Abstract [en]

    Advances in imaging and display engineering have given rise to new and improved image and videoapplications that aim to maximize visual quality under given resource constraints (e.g., power, bandwidth).Because the human visual system is an imperfect sensor, the images/videos can be represented in a mathematicallylossy fashion but with enough fidelity that the losses are visually imperceptible—commonly termed“visually lossless.” Although a great deal of research has focused on gaining a better understanding ofthe limits of human vision when viewing natural images/video, a universally or even largely accepted definitionof visually lossless remains elusive. Differences in testing methodologies, research objectives, and targetapplications have led to multiple ad-hoc definitions that are often difficult to compare to or otherwise employ inother settings. We present a compendium of technical experiments relating to both vision science and visualquality testing that together explore the research and business perspectives of visually lossless image quality,as well as review recent scientific advances. Together, the studies presented in this paper suggest that a singledefinition of visually lossless quality might not be appropriate; rather, a better goal would be to establish varyinglevels of visually lossless quality that can be quantified in terms of the testing paradigm.

  • 2. Andrén, B
    et al.
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo.
    Wang, K
    Readability of displays in bright outdoor surroundings SID Symposium Digest of Technical Papers2014In: SID Display Week 2014, 2014, p. 1100-1103Conference paper (Refereed)
  • 3. Andrén, B
    et al.
    Wang, K
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo.
    Characterizations of 3D TV: Active vs passive2012Conference paper (Refereed)
  • 4.
    Arndt, Sebastian
    et al.
    Technical University of Berlin, Germany.
    Brunnström, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Cheng, Eva
    RMIT University, Australia.
    Engelke, Ulrich
    CSIRO Commonwealth Scientific and Industrial Research Organisation, Australia.
    Moller, Sebastian
    Technical University of Berlin, Germany.
    Antons, Jan-Niklas
    Technical University of Berlin, Germany.
    Review on using physiology in quality of experience2016In: Electronic Imaging: Human Vision and Electronic Imaging 2016, 2016, p. 197-205Conference paper (Refereed)
    Abstract [en]

    In the area of Quality of Experience (QoE), one challenge is to design test methodologies in order to evaluate the perceived quality of multimedia content delivered through technical sys-tems. Traditionally, this evaluation is done using subjective opinion tests. However, sometimes it is difficult for observers to communicate the experienced quality through the given scale. Fur-thermore. those tests do not give insights into how the user is reacting on an internal physiological level. To overcome these issues, one approach is to use physiological measures, in order to derive a direct non-verbal response of the recipient. In this paper, we review studies that have been performed in the domain of QoE using physiological measures and we look into current activities in standardization bodies. We present challenges this research faces. and give an overview on what researchers should be aware of when they want to start working in this research area.

  • 5.
    Bosse, Sebastian
    et al.
    Fraunhofer, Germany.
    Brunnstrom, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Arndt, Sebastian
    NTNU Norwegian University of Science and Technology, Norway.
    Martini, Maria G.
    Kingston University, UK.
    Ramzan, Naeem
    University of the West of Scotland, UK.
    Engelke, Ulrich
    CSIRO, Australia.
    A common framework for the evaluation of psychophysiological visualquality assessment2019In: Quality and User Experience, ISSN 2366-0139, E-ISSN 2366-0147, Vol. 4, no 3Article in journal (Refereed)
    Abstract [en]

    The assessment of perceived quality based on psychophysiological methods recently gained attraction as it potentiallyovercomes certain flaws of psychophysical approaches. Although studies report promising results, it is not possible toarrive at decisive and comparable conclusions that recommend the use of one or another method for a specific applicationor research question. The video quality expert group started a project on psychophysiological quality assessment to studythese novel approaches and to develop a test plan that enables more systematic research. This test plan comprises of a specificallydesigned set of quality annotated video sequences, suggestions for psychophysiological methods to be studied inquality assessment, and recommendations for the documentation and publications of test results. The test plan is presentedin this article.

  • 6.
    Brunnstrom, Kjell
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Barkowsky, Marcus
    University of Applied Sciences, Germany.
    Statistical quality of experience analysis: on planning the sample size and statistical significance testing2018In: Journal of Electronic Imaging (JEI), ISSN 1017-9909, E-ISSN 1560-229X, Vol. 27, no 5, article id 053013Article in journal (Refereed)
    Abstract [en]

    This paper analyzes how an experimenter can balance errors in subjective video quality tests betweenthe statistical power of finding an effect if it is there and not claiming that an effect is there if the effect is not there,i.e., balancing Type I and Type II errors. The risk of committing Type I errors increases with the number ofcomparisons that are performed in statistical tests. We will show that when controlling for this and at thesame time keeping the power of the experiment at a reasonably high level, it is unlikely that the number oftest subjects that are normally used and recommended by the International Telecommunication Union (ITU),i.e., 15 is sufficient but the number used by the Video Quality Experts Group (VQEG), i.e., 24 is more likelyto be sufficient. Examples will also be given for the influence of Type I error on the statistical significance ofcomparing objective metrics by correlation. We also present a comparison between parametric and nonparametricstatistics. The comparison targets the question whether we would reach different conclusions on the statisticaldifference between the video quality ratings of different video clips in a subjective test, based on thecomparison between the student T-test and the Mann–Whitney U-test. We found that there was hardly a differencewhen few comparisons are compensated for, i.e., then almost the same conclusions are reached. Whenthe number of comparisons is increased, then larger and larger differences between the two methods arerevealed. In these cases, the parametric T-test gives clearly more significant cases, than the nonparametrictest, which makes it more important to investigate whether the assumptions are met for performing a certaintest.

  • 7.
    Brunnstrom, Kjell
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Dima, Elijs
    Mid Sweden University, Sweden.
    Andersson, Mattias
    Mid Sweden University, Sweden.
    Sjöström, Mårten
    Mid Sweden University, Sweden.
    Qureshi, Tahir
    HIAB, Sweden.
    Johanson, Mathias
    Alkit Communications AB, Sweden.
    Quality of Experience of hand controller latency in a Virtual Reality simulator2019In: Human Vision and Electronic Imaging 2019 / [ed] Damon Chandler, Mark McCourt and Jeffrey Mulligan, 2019, article id 3068450Conference paper (Refereed)
    Abstract [en]

    In this study, we investigate a VR simulator of a forestry crane used for loading logs onto a truck, mainly looking at Quality of Experience (QoE) aspects that may be relevant for task completion, but also whether there are any discomfort related symptoms experienced during task execution. A QoE test has been designed to capture both the general subjective experience of using the simulator and to study task performance. Moreover, a specific focus has been to study the effects of latency on the subjective experience, with regards to delays in the crane control interface. A formal subjective study has been performed where we have added controlled delays to the hand controller (joystick) signals. The added delays ranged from 0 ms to 800 ms. We found no significant effects of delays on the task performance on any scales up to 200 ms. A significant negative effect was found for 800 ms added delay. The Symptoms reported in the Simulator Sickness Questionnaire (SSQ) was significantly higher for all the symptom groups, but a majority of the participants reported only slight symptoms. Two out of thirty test persons stopped the test before finishing due to their symptoms.

  • 8.
    Brunnstrom, Kjell
    et al.
    RISE, Swedish ICT, Acreo.
    Tavakoli, S
    Kulyk, V
    RISE, Swedish ICT, Acreo.
    Wang, Kun
    RISE, Swedish ICT, Acreo.
    Hedberg, Christer
    RISE, Swedish ICT, Acreo.
    Ananth, IV
    RISE, Swedish ICT, Acreo.
    Hussein, M
    RISE, Swedish ICT, Acreo.
    Andrén, B
    RISE, Swedish ICT, Acreo.
    Folkesson, M
    Barowski, M
    RISE, Swedish ICT, Acreo.
    3D Video Quality of Experience - Influence of Scale and Crosstalk Invited2014Conference paper (Refereed)
    Abstract [en]

    This paper gives an overview of three recent studies by the authors on the topic of 3D video Quality of Experience (QoE). Two of studies [1,2] investigated different psychological dimension that may be needed for describing 3D video QoE and the third the visibility and annoyance of crosstalk[3]. The results shows that the video quality scale could be sufficient for evaluating S3D video experience for coding and spatial resolution reduction distortions. It was also confirmed that with a more complex mixture of degradations more than one scale should be used to capture the QoE in these cases. The study found a linear relationship between the perceived crosstalk and the amount of crosstalk.

  • 9.
    Brunnstrom, Kjell
    et al.
    RISE, Swedish ICT, Acreo. Mid Sweden University, Sweden.
    Tavakoli, Samira
    Technical University of Madrid, Spain.
    Søgaard, Jacob
    DTU Technical University of Denmark, Denmark.
    Compensating for Type-I errors in video quality assessment2015In: 2015 Seventh International Workshop on Quality of Multimedia Experience (QoMEX), 2015, article id 7148080Conference paper (Refereed)
    Abstract [en]

    This paper analyzes the impact on compensating for Type-I errors in video quality assessment. A Type-I error is to incorrectly conclude that there is an effect. The risk increases with the number of comparisons that are performed in statistical tests. Type-I errors are an issue often neglected in Quality of Experience and video quality assessment analysis. Examples are given for the analysis of subjective experiments and the evaluation of objective metrics by correlation.

  • 10.
    Brunnstrom, Kjell
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Wang, Kun
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Tavakoli, Samira
    Universidad Politecnica de Madrid, Spain.
    Andren, Börje
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Symptoms analysis of 3D TV viewing based on Simulator SicknessQuestionnaires2017In: Quality and User Experience, ISSN 2366-0139, E-ISSN 2366-0147, Vol. 2Article in journal (Refereed)
    Abstract [en]

    Stereoscopic 3D TV viewing puts differentvisual demands on the viewer compared to 2D TV viewing.Previous research has reported on viewers’ fatigue anddiscomfort and other negative effects. This study is toinvestigate further how severe and what symptoms mayarise from somewhat longish 3D TV viewing. The MPEG3DV project is working on the next-generation videoencoding standard and in this process, MPEG issued a callfor proposal of encoding algorithms. To evaluate thesealgorithms a large scale subjective test was performedinvolving Laboratories all over the world [(MPEG 2011;Baroncini 2012)]. For the participating Labs, it wasoptional to administer a slightly modified Simulator SicknessQuestionnaire (SSQ) before and after the test. One ofthe SSQ data sets described in this article is coming fromthis study. The SSQ data from the MPEG test is the largestdata set in this study and also contains the longest viewingtimes. Along with the SSQ data from the MPEG test, wehave also collected questionnaire data in three other 3D TVstudies. We did two on the same 3D TV (passive filmpattern retarder) as in the MPEG test, and one was using aprojector system. As comparison SSQ data from a 2Dvideo quality experiment is also presented. This investigationshows a statistically significant increase in symptomsafter viewing 3D TV primarily related to the visual or Oculomotor system. Surprisingly, 3D video viewing usingprojectors did not show this effect.

  • 11.
    Brunnström, Kjell
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Barkowsky, Marcus
    Balancing type I errors and statistical power in video quality assessment2017In: IS and T International Symposium on Electronic Imaging Science and Technology, 2017, p. 91-96Conference paper (Refereed)
    Abstract [en]

    This paper analyzes how an experimenter can balance errors in subjective video quality tests between the statistical power of finding an effect if it is there and not claiming that an effect is there if the effect it is not there i.e. balancing Type I and Type II errors. The risk of committing Type I errors increases with the number of comparisons that are performed in statistical tests. We will show that when controlling for this and at the same time keeping the power of the experiment at a reasonably high level, it will require more test subjects than are normally used and recommended by international standardization bodies like the ITU. Examples will also be given for the influence of Type I error on the statistical significance of comparing objective metrics by correlation.

  • 12.
    Brunnström, Kjell
    et al.
    RISE, Swedish ICT, Acreo.
    Hands, D
    Speranza, F
    Webster, A
    VQEG Validation ITU Standardisation of Objective Perceptual Video Quality Metrics2009In: IEEE Signal Processing Magazine, Vol. 26, no 3, p. 96-Article in journal (Refereed)
  • 13.
    Brunnström, Kjell
    et al.
    RISE, Swedish ICT, Acreo.
    Schenkman, B
    Comparison of the predictions of a spatiotemporal model with the detection of distortion in small moving images2002In: Optical Engineering, Vol. 41, p. 711-22Article in journal (Refereed)
  • 14.
    Brunnström, Kjell
    et al.
    RISE, Swedish ICT, Acreo.
    Schenkman, B
    Jacobson, B
    Object Detection in Cluttered IR Images2003In: Optical Engineering, Vol. 42, p. 388-99Article in journal (Refereed)
  • 15.
    Brunnström, Kjell
    et al.
    Mid Sweden University, Sweden.
    Sjöström, Mårten
    Mid Sweden University, Sweden.
    Muhammad, Imran
    HIAB AB, Sweden;Mid Sweden University, Sweden.
    Magnus, Pettersson
    HIAB AB, Sweden.
    Johanson, Mathias
    Alkit Communications AB, Sweden.
    Quality of Experience for a Virtual Reality simulator2018In: Human Vision and Electronic Imaging 2018 / [ed] Rogowitz, B.;Pappas, T.;De Ridder H., The Society for Imaging Science and Technology, 2018Conference paper (Refereed)
    Abstract [en]

    In this study, we investigate a VR simulator of a forestry crane used for loading logs onto a truck, mainly looking at Quality of Experience (QoE) aspects that may be relevant for task completion, but also whether there are any discomfort related symptoms experienced during task execution. The QoE test has been designed to capture both the general subjective experience of using the simulator and to study task completion rate. Moreover, a specific focus has been to study the effects of latency on the subjective experience, with regards both to delays in the crane control interface as well as lag in the visual scene rendering in the head mounted display (HMD). Two larger formal subjective studies have been performed: one with the VR-system as it is and one where we have added controlled delay to the display update and to the joystick signals. The baseline study shows that most people are more or less happy with the VR-system and that it does not have strong effects on any symptoms as listed in the Simulator Sickness Questionnaire (SSQ). In the delay study we found significant effects on Comfort Quality and Immersion Quality for higher Display delay (30 ms), but very small impact of joystick delay. Furthermore, the Display delay had strong influence on the symptoms in the SSQ, and causing test subjects to decide not to continue with the complete experiments. We found that this was especially connected to the longer added Display delays (≥ 20 ms).

  • 16.
    Brunnström, Kjell
    et al.
    RISE, Swedish ICT, Acreo.
    Stålenbring, D
    Pettersson, M
    Gustafsson, J
    The impact of transmission errors on progressive 720 lines HDTV coded with H.2642010In: Proceedings Volume 7527, Human Vision and Electronic Imaging XV; 75271J (2010), 2010, Vol. 7527Conference paper (Refereed)
  • 17.
    Dima, Elijs
    et al.
    Mid Sweden University, Sweden.
    Brunnstrom, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Sjöström, Mårten
    Mid Sweden University, Sweden.
    Andersson, Mattias
    Mid Sweden University, Sweden.
    Edlund, Joakim
    Mid Sweden University, Sweden.
    Johanson, Mathias
    Alkit Communications AB, Sweden.
    Qureshi, Tahir
    HIAB AB, Sweden.
    View Position Impact on QoE in an Immersive Telepresence System for Remote Operation2019In: 2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX), Berlin, Germany: IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate how different viewingpositions affect a user’s Quality of Experience (QoE) and performancein an immersive telepresence system. A QoE experimenthas been conducted with 27 participants to assess the generalsubjective experience and the performance of remotely operatinga toy excavator. Two view positions have been tested, an overheadand a ground-level view, respectively, which encourage relianceon stereoscopic depth cues to different extents for accurate operation.Results demonstrate a significant difference between groundand overhead views: the ground view increased the perceiveddifficulty of the task, whereas the overhead view increased theperceived accomplishment as well as the objective performanceof the task. The perceived helpfulness of the overhead view wasalso significant according to the participants.

  • 18.
    Engelke, Ulrich
    et al.
    Commonwealth Scientific and Industrial Research Organisation, Australia.
    Darcy, Daniel P.
    Dolby Laboratories, USA.
    Mulliken, Grant H.
    Dolby Laboratories, USA.
    Bosse, Sebstian
    Fraunhofer Institute for Telecommunications, Germany.
    Martini, Maria G.
    Kingston University, UK.
    Arndt, Sebstian
    NTNU Norwegian University of Science and Technology, Norway.
    Antons, Jan Niklas
    Technische Universiät Berlin, Germany.
    Chan, Kit Y.
    Curtin University, Australia.
    Ramzan, Naeem
    University of the West of Scotland, UK.
    Brunnstrom, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Psychophysiology-Based QoE Assessment: A Survey2017In: IEEE Journal on Selected Topics in Signal Processing, ISSN 1932-4553, E-ISSN 1941-0484, Vol. 11, no 1, p. 6-21, article id 7569001Article in journal (Refereed)
    Abstract [en]

    We present a survey of psychophysiology-based assessment for quality of experience (QoE) in advanced multimedia technologies. We provide a classification of methods relevant to QoE and describe related psychological processes, experimental design considerations, and signal analysis techniques. We summarize multimodal techniques and discuss several important aspects of psychophysiology-based QoE assessment, including the synergies with psychophysical assessment and the need for standardized experimental design. This survey is not considered to be exhaustive but serves as a guideline for those interested to further explore this emerging field of research.

  • 19. Garcia, M. -N
    et al.
    De Simone, F.
    Tavakoli, S.
    Staelens, N.
    Egger, S.
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo.
    Raake, A.
    Quality of experience and HTTP adaptive streaming: A review of subjective studies2014In: 2014 6th International Workshop on Quality of Multimedia Experience, QoMEX 2014, 2014, p. 141-146Conference paper (Refereed)
    Abstract [en]

    HTTP adaptive streaming technology has become widely spread in multimedia services because of its ability to provide adaptation to characteristics of various viewing devices and dynamic network conditions. There are various studies targeting the optimization of adaptation strategy. However, in order to provide an optimal viewing experience to the end-user, it is crucial to get knowledge about the Quality of Experience (QoE) of different adaptation schemes. This paper overviews the state of the art concerning subjective evaluation of adaptive streaming QoE and highlights the challenges and open research questions related to QoE assessment. © 2014 IEEE.

  • 20.
    Hermann, David
    et al.
    Volvo Car Corporation AB, Sweden.
    Djupsjöbacka, Anders
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Andrén, Börje
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Brunnström, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Rydell, Niclas
    TCO Development AB, Sweden.
    Display panel certification system for the vehicle industry2017In: Digest of Technical Papers - SID International Symposium, 2017, Vol. 48, no 1, p. 471-474Conference paper (Refereed)
    Abstract [en]

    The ever-increasing need for displaying in-vehicle visual information in a non-distracting way requires a high visual performance of automotive displays. For their procurement, deep technical and supply-chain knowledge is required. Therefore, based on our comparisons of in-vehicle and laboratory visual-performance measurements, we propose a certification system for automotive display panels.

  • 21. Schmidmer, C
    et al.
    Takahashi, A
    Pinson, M
    Winkler, S
    Brunnström, Kjell
    RISE, Swedish ICT, Acreo.
    Mu, M
    Mauthe, A
    An Interview with Video Quality Experts2009Other (Other academic)
    Abstract [sv]

    Artikel i nyhetsbrev

  • 22. Sedano, I
    et al.
    Brunnström, Kjell
    RISE, Swedish ICT, Acreo.
    Kihl, M
    Aurelius, A
    Full-reference video quality metric assisted development of no-reference video quality metrics for real time network monitoring2014In: EURASIP Journal on Image and Video Processing, ISSN 1687-5176, E-ISSN 1687-5281, no 4Article in journal (Refereed)
  • 23.
    Sedano, Inigo
    et al.
    Tecnalia Research and Innovation, Spain.
    Prieto, Gorka
    University of the Basque Country, Spain.
    Brunnstrom, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Kihl, Maria
    Lund University, Sweden.
    Montalban, Jon
    University of the Basque Country, Spain.
    Application of full-reference video quality metrics in IPTV2017In: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB, 2017Conference paper (Refereed)
    Abstract [en]

    Executing an accurate full-reference metric such as VQM can take minutes in an average computer for just one user. Therefore, it can be unfeasible to analyze all the videos received by users in an IPTV network for example consisting of 10.000 users using a single computer running the VQM metric. One solution can be to use a lightweight no-reference metrics in addition to the full-reference metric mentioned. Lightweight no-reference metrics can be used for discarding potential situations to evaluate because they are accurate enough for that task, and then the full-reference metric VQM can be used when more accuracy is needed. The work in this paper is focused on determining the maximum number of situations/users that can be analyzed simultaneously using the VQM metric in a computer with good performance. The full-reference metric is applied on the transmitter using a method specified in the recommendation ITU BT.1789. The best performance achieved was 112.8 seconds per process.

  • 24.
    Segaard, Jacob
    et al.
    DTU Technical University of Denmark, Denmark.
    Tavakolf, Samira
    Technical University of Madrid, Spain.
    Brunnstrom, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Garcia, Narciso
    Technical University of Madrid, Spain.
    Subjective analysis and objective characterization of adaptive bitrate videos2016In: Electronic Imaging: Human Vision and Electronic Imaging 2016, 2016, p. 55-63Conference paper (Refereed)
    Abstract [en]

    The HTTP Adaptive Streaming (HAS) technology allows video service providers to improve the network utilization and thereby increasing the end-users' Quality of Experience (QoE). This has made HAS a widely used approach for audiovisual delivery There are several previous studies aiming to identify the factors influencing on subjective QoE of adaptation events. However, adapting the video quality typically lasts m a time scale much longer than what current standardized subjective testing methods are designed for. thus making the full matrix design of the experiment on an event level hard to achieve. In this study, we investigated the overall subjective QoE of 6 minutes long video sequences containing different sequential adaptation events. This was compared to a dataset from our previous work performed to evaluate the individual adaptation events. We could then derive a relationship between the overall mean opinion score (MOS) and the MOS from shorter sequences. The aforementioned empirical dataset has proven to be very challenging in terms of video quality assessment test design, thus deriving a conclusive outcome about the influence of different parameters have been difficult. The second contribution of this study is considering how objective characterizations of adapted videos can improve the understanding of the subjective ratings.

  • 25. Shahid, M.
    et al.
    Sogaard, J.
    Pokhrel, J.
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo.
    Wang, K
    RISE, Swedish ICT, Acreo.
    Tavakoli, S.
    Gracia, N.
    Crowdsourcing based subjective quality assessment of adaptive video streaming2014In: 2014 6th International Workshop on Quality of Multimedia Experience, QoMEX 2014, 2014, p. 53-54Conference paper (Refereed)
    Abstract [en]

    In order to cater for user's quality of experience (QoE) requirements, HTTP adaptive streaming (HAS) based solutions of video services have become popular recently. User QoE feedback can be instrumental in improving the capabilities of such services. Perceptual quality experiments that involve humans are considered to be the most valid method of the assessment of QoE. Besides lab-based subjective experiments, crowdsourcing based subjective assessment of video quality is gaining popularity as an alternative method. This paper presents insights into a study that investigates perceptual preferences of various adaptive video streaming scenarios through crowdsourcing based subjective quality assessment.

  • 26.
    Søgaard, Jacob
    et al.
    DTU Technical University of Denmark, Denmark.
    Forchhammer, Søren
    DTU Technical University of Denmark, Denmark.
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo. Mid Sweden University, Sweden.
    Quality assessment of adaptive bitrate videos using image metrics and machine learning2015In: 2015 Seventh International Workshop on Quality of Multimedia Experience (QoMEX), 2015, article id 7148105Conference paper (Refereed)
    Abstract [en]

    Adaptive bitrate (ABR) streaming is widely used for distribution of videos over the internet. In this work, we investigate how well we can predict the quality of such videos using well-known image metrics, information about the bitrate levels, and a relatively simple machine learning method. Quality assessment of ABR videos is a hard problem, but our initial results are promising. We obtain a Spearman rank order correlation of 0.88 using content-independent cross-validation.

  • 27.
    Søgaard, Jacob
    et al.
    DTU Technical University of Denmark, Denmark.
    Shahid, Muhammad
    Blekinge Institute of Technology, Sweden.
    Pokhrel, Jeevan
    Montimage, France.
    Brunnström, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo.
    On subjective quality assessment of adaptive video streaming via crowdsourcing and laboratory based experiments2017In: Multimedia tools and applications, ISSN 1380-7501, E-ISSN 1573-7721, Vol. 76, no 15, p. 16727-16748Article in journal (Refereed)
    Abstract [en]

    Video streaming services are offered over the Internet and since the service providers do not have full control over the network conditions all the way to the end user, streaming technologies have been developed to maintain the quality of service in these varying network conditions i.e. so called adaptive video streaming. In order to cater for users’ Quality of Experience (QoE) requirements, HTTP based adaptive streaming solutions of video services have become popular. However, the keys to ensure the users a good QoE with this technology is still not completely understood. User QoE feedback is therefore instrumental in improving this understanding. Controlled laboratory based perceptual quality experiments that involve a panel of human viewers are considered to be the most valid method of the assessment of QoE. Besides laboratory based subjective experiments, crowdsourcing based subjective assessment of video quality is gaining popularity as an alternative method. This article presents insights into a study that investigates perceptual preferences of various adaptive video streaming scenarios through crowdsourcing based and laboratory based subjective assessment. The major novel contribution of this study is the application of Paired Comparison based subjective assessment in a crowdsourcing environment. The obtained results provide some novel indications, besides confirming the earlier published trends, of perceptual preferences for adaptive scenarios of video streaming. Our study suggests that in a network environment with fluctuations in the bandwidth, a medium or low video bitrate which can be kept constant is the best approach. Moreover, if there are only a few drops in bandwidth, one can choose a medium or high bitrate with a single or few buffering events.

  • 28. Tavakoli, S.
    et al.
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo.
    Wang, K.
    RISE, Swedish ICT, Acreo.
    Andrén, B.
    RISE, Swedish ICT, Acreo.
    Shahid, M.
    Garcia, N.
    Subjective quality assessment of an adaptive video streaming model2014In: Proceedings of SPIE - The International Society for Optical Engineering, 2014Conference paper (Refereed)
    Abstract [en]

    With the recent increased popularity and high usage of HTTP Adaptive Streaming (HAS) techniques, various studies have been carried out in this area which generally focused on the technical enhancement of HAS technology and applications. However, a lack of common HAS standard led to multiple proprietary approaches which have been developed by major Internet companies. In the emerging MPEG-DASH standard the packagings of the video content and HTTP syntax have been standardized; but all the details of the adaptation behavior are left to the client implementation. Nevertheless, to design an adaptation algorithm which optimizes the viewing experience of the enduser, the multimedia service providers need to know about the Quality of Experience (QoE) of different adaptation schemes. Taking this into account, the objective of this experiment was to study the QoE of a HAS-based video broadcast model. The experiment has been carried out through a subjective study of the end user response to various possible clients' behavior for changing the video quality taking different QoE-influence factors into account. The experimental conclusions have made a good insight into the QoE of different adaptation schemes which can be exploited by HAS clients for designing the adaptation algorithms.

  • 29. Tavakoli, S.
    et al.
    Shahid, M.
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo.
    Lovstrom, B.
    Garcia, N.
    Effect of content characteristics on quality of experience of adaptive streaming2014In: 2014 6th International Workshop on Quality of Multimedia Experience, QoMEX 2014, 2014, p. 63-64Conference paper (Refereed)
    Abstract [en]

    The growing popularity of adaptive streaming-based video delivery nowadays has raised the interest about the user's perception when experiencing quality adaptation. The impact of the video content characteristics on user's perceptual quality has already become evident. The aim of this study is to investigate the influence of this factor on the quality of experience of adaptive streaming scenarios. Our results show that the perceptual quality of adaptation strategies applied on videos with high spatial and low temporal amount of activity is significantly lower compared to the other content types. .

  • 30.
    Tavakoli, Samira
    et al.
    Technical University of Madrid, Spain.
    Brunnstrom, Kjell
    RISE, Swedish ICT, Acreo. Mid Sweden University, Sweden.
    Garcia, Narciso
    Technical University of Madrid, Spain.
    About Subjective Evaluation of Adaptive Video Streaming2015In: Human Vision and Electronic Imaging XX / [ed] Bernice E. Rogowitz, Thrasyvoulos N. Pappas, Huib de Ridder, 2015, Vol. 9394, article id 939407Conference paper (Refereed)
    Abstract [en]

    The usage of HTTP Adaptive Streaming (HAS) technology by content providers is increasing rapidly. Having available the video content in multiple qualities, using HAS allows to adapt the quality of downloaded video to the current network conditions providing smooth video-playback. However, the time-varying video quality by itself introduces a new type of impairment. The quality adaptation can be done in different ways. In order to find the best adaptation strategy maximizing users perceptual quality it is necessary to investigate about the subjective perception of adaptation-related impairments. However, the novelties of these impairments and their comparably long time duration make most of the standardized assessment methodologies fall less suited for studying HAS degradation. Furthermore, in traditional testing methodologies, the quality of the video in audiovisual services is often evaluated separated and not in the presence of audio. Nevertheless, the requirement of jointly evaluating the audio and the video within a subjective test is a relatively under-explored research field. In this work, we address the research question of determining the appropriate assessment methodology to evaluate the sequences with time-varying quality due to the adaptation. This was done by studying the influence of different adaptation related parameters through two different subjective experiments using a methodology developed to evaluate long test sequences. In order to study the impact of audio presence on quality assessment by the test subjects, one of the experiments was done in the presence of audio stimuli. The experimental results were subsequently compared with another experiment using the standardized single stimulus Absolute Category Rating (ACR) methodology.

  • 31.
    Tavakoli, Samira
    et al.
    Technical University of Madrid, Spain.
    Brunnström, Kjell
    RISE, Swedish ICT, Acreo. Mid Sweden University, Sweden.
    Gutierrez, Jesús
    Technical University of Madrid, Spain.
    Garcia, Narciso
    Technical University of Madrid, Spain.
    Quality of Experience of Adaptive Video Streaming: Investigation in Service Parameters and Subjective Quality Assessment Methodology2015In: Signal processing. Image communication, ISSN 0923-5965, E-ISSN 1879-2677, Vol. 39, no B, p. 432-443Article in journal (Refereed)
    Abstract [en]

    The usage of HTTP adaptive streaming (HAS) has become widely spread in multimedia services. Because it allows the service providers to improve the network resource utilization user's Quality of Experience (QoE). Using this technology, the video playback interruption is reduced since the network server status in addition to capability of user device, all are taken into account by HAS client to adapt the quality to the current condition. Adaptation can be done using different strategies. In order to provide optimal QoE, the perceptual impact of adaptation strategies from point of view of the user should be studied. However, the time-varying video quality due to the adaptation which usually takes place in a long interval introduces a new type of impairment making the subjective evaluation of adaptive streaming system challenging. The contribution of this paper is two-fold: first, it investigates the testing methodology to evaluate HAS QoE by comparing the subjective experimental outcomes obtained from ACR standardized method a semi-continuous method developed to evaluate the long sequences. In addition, influence of using audiovisual stimuli to evaluate the video-related impairment is inquired. Second, impact of some of the adaptation technical factors including the quality switching amplitude chunk size in combination with high range of commercial content type is investigated. The results of this study provide a good insight toward achieving appropriate testing method to evaluate HAS QoE, in addition to designing switching strategies with optimal visual quality.

  • 32.
    Tavakoli, Samira
    et al.
    Polytechnic University of Madrid, Spain.
    Egger, Sebastian
    Austrian Institute of Technology, Austria; Graz University of Technology, Austria.
    Seufert, Michael
    University of Würzburg, Germany.
    Schatz, Raimund
    Austrian Institute of Technology, Austria.
    Brunnström, Kjell
    RISE, Swedish ICT, Acreo. Mid Sweden University, Sweden.
    Garcia, Narciso
    Polytechnic University of Madrid, Spain.
    Perceptual quality of HTTP adaptive streaming strategies: Cross-experimental analysis of multi-laboratory and crowdsourced subjective studies2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 34, no 8, p. 2141-2153, article id 7485884Article in journal (Refereed)
    Abstract [en]

    Today's packet-switched networks are subject to bandwidth fluctuations that cause degradation of the user experience of multimedia services. In order to cope with this problem, HTTP adaptive streaming (HAS) has been proposed in recent years as a video delivery solution for the future Internet and being adopted by an increasing number of streaming services, such as Netflix and Youtube. HAS enables service providers to improve users' quality of experience (QoE) and network resource utilization by adapting the quality of the video stream to the current network conditions. However, the resulting time-varying video quality caused by adaptation introduces a new type of impairment and thus novel QoE research challenges. Despite various recent attempts to investigate these challenges, many fundamental questions regarding HAS perceptual performance are still open. In this paper, the QoE impact of different technical adaptation parameters, including chunk length, switching amplitude, switching frequency, and temporal recency, are investigated. In addition, the influence of content on perceptual quality of these parameters is analyzed. To this end, a large number of adaptation scenarios have been subjectively evaluated in four laboratory experiments and one crowdsourcing study. A statistical analysis of the combined data set reveals results that partly contradict widely held assumptions and provide novel insights in perceptual quality of adapted video sequences, e.g., interaction effects between quality switching direction (up/down) and switching strategy (smooth/abrupt). The large variety of experimental configurations across different studies ensures the consistency and external validity of the presented results that can be utilized for enhancing the perceptual performance of adaptive streaming services.

  • 33. Wang, K
    et al.
    Barkowsky, M
    Brunnström, Kjell
    RISE, Swedish ICT, Acreo.
    Sjöström, M
    Cousseau, R
    Le Callet, P
    Perceived 3D TV transmission quality assessment: Multi-laboratory results using Absolute Category Rating on Quality of Experience scale2012In: IEEE transactions on broadcasting, ISSN 0018-9316, E-ISSN 1557-9611, Vol. 58, no 4, p. 544-Article in journal (Refereed)
1 - 33 of 33
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