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  • 1.
    Almquist, Mathias
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Almquist, Viktor
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Eager, Derek
    Univ Saskatchewan, Canada.
    The Prefetch Aggressiveness Tradeof in 360 degrees Video Streaming2018In: PROCEEDINGS OF THE 9TH ACM MULTIMEDIA SYSTEMS CONFERENCE (MMSYS18), ASSOC COMPUTING MACHINERY , 2018, p. 258-269Conference paper (Refereed)
    Abstract [en]

    With 360 degrees video, only a limited fraction of the full view is displayed at each point in time. This has prompted the design of streaming delivery techniques that allow alternative playback qualities to be delivered for each candidate viewing direction. However, while prefetching based on the users expected viewing direction is best done close to playback deadlines, large buffers are needed to protect against shortfalls in future available bandwidth. This results in conflicting goals and an important prefetch aggressiveness tradeoff problem regarding how far ahead in time from the current playpoint prefetching should be done. This paper presents the first characterization of this tradeoff. The main contributions include an empirical characterization of head movement behavior based on data from viewing sessions of four different categories of 360 degrees video, an optimization-based comparison of the prefetch aggressiveness tradeoffs seen for these video categories, and a data-driven discussion of further optimizations, which include a novel system design that allows both tradeoff objectives to be targeted simultaneously. By qualitatively and quantitatively analyzing the above tradeoffs, we provide insights into how to best design tomorrows delivery systems for 360 degrees videos, allowing content providers to reduce bandwidth costs and improve users playback experiences.

  • 2.
    Bianco, A.
    et al.
    Dipartimento di Elettronica e Delie Telecomunicazioni, Politecnico di Torino, Italy.
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Li, N.
    Dipartimento di Elettronica e Delie Telecomunicazioni, Politecnico di Torino, Italy.
    Giraudo, L.
    VMware, Inc, United States.
    OpenFlow driven ethernet traffic analysis2014In: 2014 IEEE International Conference on Communications, ICC 2014, IEEE Computer Society , 2014, no 6883781, p. 3001-3006Conference paper (Refereed)
    Abstract [en]

    Software Defined Networking (SDN) is a new networking paradigm that permits to slice network infrastructures. An example of SDN is the OpenFlow framework, where the control plane runs on a separate device, called controller, that manages data forwarding switches. The OpenFlow protocol ensures communications between OpenFlow switches and the OpenFlow controller. Before widely deploying OpenFlow based networks, scalability and performance of such networks should be studied and better understood. In this paper, the scalability of NOX, one of the most popular OpenFlow controller, is analyzed through both simulation and lab measurements. We perform an Ethernet trace analysis on the controller by defining flow characteristics as would be seen by an OpenFlow controller. We study the potential trace impact on an OpenFlow controller, analyzing among others, the number of flows, flow inter arrival times, traffic volumes and flow size distribution. Our results permit to discuss the feasibility of running OpenFlow networks with a single commodity PC as the controller in a mid-size campus network. © 2014 IEEE.

  • 3.
    Carlsson, Niklas
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Eager, Derek
    University of Saskatchewan, Canada.
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Optimized Adaptive Streaming of Multi-video Stream Bundles2017In: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 19, no 7, p. 1637-1653Article in journal (Refereed)
    Abstract [en]

    In contrast to traditional video, multi-view video streaming allows viewers to interactively switch among multiple perspectives provided by different cameras. One approach to achieve such a service is to encode the video from all of the cameras into a single stream, but this has the disadvantage that only a portion of the received video data will be used, namely that required for the selected view at each point in time. In this paper, we introduce the concept of a multi-video stream bundle that consists of multiple parallel video streams that are synchronized in time, each providing the video from a different camera capturing the same event or movie. For delivery we leverage the adaptive features and time-based chunking of HTTP-based adaptive streaming, but now employing adaptation in both content and rate. Users are able to change their viewpoint on-demand and the client player adapts the rate at which data are retrieved from each stream based on the users current view, the probabilities of switching to other views, and the users current bandwidth conditions. A crucial component of such a system is the prefetching policy. For this we present an optimization model as well as a simpler heuristic that can balance the playback quality and the probability of playback interruptions. After analytically and numerically characterizing the optimal solution, we present a prototype implementation and sample results. Our prefetching and buffer management solution is shown to provide close to seamless playback switching when there is sufficient bandwidth to prefetch the parallel streams.

  • 4.
    Gustafsson, Josef
    et al.
    Linköping University.
    Hiran, Rahul
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    The hidden mailman and his mailbag: Routing path analysis from a European perspective2017In: 2017 IEEE International Conference on Communications (ICC) / [ed] Debbah M.,Gesbert D.,Mellouk A., IEEE, 2017, p. 1-7Conference paper (Refereed)
    Abstract [en]

    The postal system is often used as an analogy when describing Internet routing. However, in addition to similarities, there are some significant differences. First, and most importantly, the Autonomous Systems (ASes) that operate the routers along the end-to-end path of a packet can often inspect and manipulate the packet and its content. Second, due to lack of secure routing mechanisms, packet paths can be diverted through additional non-trusted ASes. Although we often know the first network we connect through and the service that we access, we seldom know the networks that forward our packets. We can think of these networks as hidden mailmen. To better understand these networks and their potential access to information, we characterize the ASes along the paths of typical Internet packets between European example clients and the most popular web domains. We also identify ASes and countries with higher path coverage and investigate if there are differences in the HTTPS usage among paths that may take additional detours. Our results highlight the role played by North American (typically US-based) ASes and glean insights into how vulnerable the detoured traffic is to man-in-the-middle attacks compared to regular traffic.

  • 5.
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Efficient and Adaptive Content Delivery of Linear and Interactive Branched Videos2016Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Video streaming over the Internet has gained tremendous popularity over recent years and currently constitutes the majority of Internet traffic. The on-demand delivery of high quality video streaming has been enabled by a combination of consistent improvements in residential download speeds, HTTP-based Adaptive Streaming (HAS), extensive content caching, and the use of Content Distribution Networks (CDNs). However, as large-scale on-demand streaming is gaining popularity, several important questions and challenges remain unanswered, including determining how the infrastructure can best be leveraged to provide users with the best possible playback experience. In addition, it is important to develop new techniques and protocols that facilitate the next generation of streaming applications. Innovative services such as interactive branched streaming are gaining popularity and are expected to be the next big thing in on-demand entertainment.

    The major contributions of this thesis are in the area of efficient content delivery of video streams using HAS. To address the two challenges above, the work utilizes a combination of different methods and tools, ranging from real-world measurements, characterization of system performance, proof-of-concept implementations, protocol optimization, and evaluation under realistic environments. First, through careful experiments, we evaluate the performance impact and interaction of HAS clients with proxy caches. Having studied the typical interactions between HAS clients and caches, we then design and evaluate content-aware policies to be used by the proxy caches, which parse the client requests and prefetch the chunks that are most likely to be requested next. In addition, we also design cooperative policies in which clients and proxies share information about the playback session. Our evaluations reveal that, in general, the bottleneck location and network conditions play central roles in which policy choices are most advantageous, and the location of the bottlenecks significantly impact the relative performance differences between policy classes. We also show that careful design and policy selection is important when trying to enhance HAS performance using proxy assistance.

    Second, this thesis proposes, models, designs, and evaluates novel streaming applications such as interactive branched videos. In such videos, users can influence the content that is being shown to them. We design and evaluate careful prefetching policies that provides seamless playback even when the users defer their path choices to the last possible moment. We derive optimized prefetching policies using an optimization framework, design and implement effective buffer management techniques for seamless playback at branch points, and use parallel TCP connections to achieve efficient buffer workahead. Through performance evaluations, we show that our policies can effectively prefetch data of carefully adapted qualities along multiple alternative paths so to ensure seamless playback, offering users a pleasant viewing experience without playback interruptions.

  • 6.
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Efficient HTTP-based Adaptive Streaming of Linear and Interactive Videos2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Online video streaming has gained tremendous popularity over recent years and currently constitutes the majority of Internet traffic. As large-scale on-demand streaming continues to gain popularity, several important questions and challenges remain unanswered. This thesis addresses open questions in the areas of efficient content delivery for HTTP-based Adaptive Streaming (HAS) from different perspectives (client, network and content provider) and in the design, implementation, and evaluation of interactive streaming applications over HAS.

    As streaming usage scales and new streaming services emerge, continuous improvements are required to both the infrastructure and the techniques used to deliver high-quality streams. In the context of Content Delivery Network (CDN) nodes or proxies, this thesis investigates the interaction between HAS clients and proxy caches. In particular, we propose and evaluate classes of content-aware and collaborative policies that take advantage of information that is already available, or share information among elements in the delivery chain, where all involved parties can benefit. Asides from the users’ playback experience, it is also important for content providers to minimize users’ startup times. We have designed and evaluated different classes of client-side policies that can prefetch data from the videos that the users are most likely to watch next, without negatively affecting the currently watched video. To help network providers to monitor and ensure that their customers enjoy good playback experiences, we have proposed and evaluated techniques that can be used to estimate clients’ current buffer conditions. Since several services today stream over HTTPS, our solution is adapted to predict client buffer conditions by only observing encrypted network-level traffic. Our solution allows the operator to identify clients with low-buffer conditions and implement policies that help avoid playback stalls.

    The emergence of HAS as the de facto standard for delivering streaming content also opens the door to use it to deliver the next generation of streaming services, such as various forms of interactive services. This class of services is gaining popularity and is expected to be the next big thing in entertainment. For the area of interactive streaming, this thesis proposes, models, designs, and evaluates novel streaming applications such as interactive branched videos and multi-video stream bundles. For these applications, we design and evaluate careful prefetching policies that provides seamless playback (without stalls or switching delay) even when interactive branched video viewers defer their choices to the last possible moment and when users switches between alternative streams within multi-video stream bundles. Using optimization frameworks, we design and implement effective buffer management techniques for seamless playback experiences and evaluate several tradeoffs using our policies.  

    List of papers
    1. Helping Hand or Hidden Hurdle: Proxy-assisted HTTP-based Adaptive Streaming Performance
    Open this publication in new window or tab >>Helping Hand or Hidden Hurdle: Proxy-assisted HTTP-based Adaptive Streaming Performance
    Show others...
    2013 (English)In: Modeling, Analysis & Simulation of Computer and Telecommunication Systems (MASCOTS), 2013 IEEE 21st International Symposium, IEEE , 2013, p. 182-191Conference paper, Published paper (Refereed)
    Abstract [en]

    HTTP-based Adaptive Streaming (HAS) has become a widely-used video delivery technology. Use of HTTP enables relatively easy firewall/NAT traversal and content caching. While caching is an important aspect of HAS, there is not much public research on the performance impact proxies and their policies have on HAS. In this paper we build an experimental framework using open source Squid proxies and the most recent Open Source Media Framework (OSMF). A range of content-aware policies can be implemented in the proxies and tested, while the player software can be instrumented to measure performance as seen at the client. Using this framework, the paper makes three main contributions. First, we present a scenario-based performance evaluation of the latest version of the OSMF player. Second, we quantify the benefits using different proxy-assisted solutions, including basic best effort policies and more advanced content quality aware prefetching policies. Finally, we present and evaluate a cooperative framework in which clients and proxies share information to improve performance. In general, the bottleneck location and network conditions play central roles in which policy choices are most advantageous, as they significantly impact the relative performance differences between policy classes. We conclude that careful design and policy selection is important when trying to enhance HAS performance using proxy assistance.

    Place, publisher, year, edition, pages
    IEEE, 2013
    Series
    Modeling, Analysis, and Simulation of Com puter and Telecommunications Systems, ISSN 1526-7539
    Keywords
    HTTP-based adaptive streaming, Proxy assisted
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-105282 (URN)10.1109/MASCOTS.2013.26 (DOI)000347906000019 ()978-0-7695-5102-9 (ISBN)978-1-4799-1209-4 (ISBN)
    Conference
    IEEE 21st International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS), 14-16 August 2013, San Francisco, CA, USA
    Available from: 2014-03-15 Created: 2014-03-15 Last updated: 2019-07-03Bibliographically approved
    2. Bandwidth-aware Prefetching for Proactive Multi-video Preloading and Improved HAS Performance
    Open this publication in new window or tab >>Bandwidth-aware Prefetching for Proactive Multi-video Preloading and Improved HAS Performance
    Show others...
    2015 (English)In: Proceedings of the ACM International Conference on Multimedia (ACM Multimedia), New York, USA: Association for Computing Machinery (ACM), 2015, p. 551-560Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper considers the problem of providing users playing one streaming video the option of instantaneous and seamless playback of alternative videos. Recommendation systems can easily provide a list of alternative videos, but there is little research on how to best eliminate the startup time for these alternative videos. The problem is motivated by services that want to retain increasingly impatient users, who frequently watch the beginning of multiple videos, before viewing a video to the end. We present the design, implementation, and evaluation of an HTTP-based Adaptive Streaming (HAS) solution that provides careful prefetching and buffer management. We also present the design and evaluation of three fundamental policy classes that provide different tradeoffs between how aggressively new alternative videos are prefetched versus the importance of ensuring high playback quality. We show that our solution allows us to reduce the startup times of alternative videos by an order of magnitude and effectively adapt the quality such as to ensure the highest possible playback quality of the video being viewed. By improving the channel utilization we also address the discrimination problem that HAS clients often suffer from, allowing us to in some cases simultaneously improve the playback quality of the video being viewed and provide the value-added service of allowing instantaneous playback of the prefetched alternative videos.

    Place, publisher, year, edition, pages
    New York, USA: Association for Computing Machinery (ACM), 2015
    Keywords
    HTTP-based adaptive streaming (HAS); Bandwidth-aware prefetching; Multi-video preloading; Seamless playback
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-128168 (URN)10.1145/2733373.2806270 (DOI)000387861300064 ()978-1-4503-3459-4 (ISBN)
    Conference
    ACM Multimedia 2015
    Available from: 2016-05-20 Created: 2016-05-19 Last updated: 2018-02-06
    3. BUFFEST: Predicting Buffer Conditions and Real-time Requirements of HTTP(S) Adaptive Streaming Clients
    Open this publication in new window or tab >>BUFFEST: Predicting Buffer Conditions and Real-time Requirements of HTTP(S) Adaptive Streaming Clients
    2017 (English)In: MMSys’17, Proceedings of the 8th ACM on Multimedia Systems Conference, ACM , 2017, p. 76-87Conference paper, Published paper (Refereed)
    Abstract [en]

    Stalls during video playback are perhaps the most important indicator of a client's viewing experience. To provide the best possible service, a proactive network operator may therefore want to know the buffer conditions of streaming clients and use this information to help avoid stalls due to empty buffers. However, estimation of clients' buffer conditions is complicated by most streaming services being rate-adaptive, and many of them also encrypted. Rate adaptation reduces the correlation between network throughput and client buffer conditions. Usage of HTTPS prevents operators from observing information related to video chunk requests, such as indications of rate adaptation or other HTTP-level information.; AB@This paper presents BUFFEST, a novel classification framework that can be used to classify and predict streaming clients' buffer conditions from both HTTP and HTTPS traffic. To illustrate the tradeoffs between prediction accuracy and the available information used by classifiers, we design and evaluate classifiers of different complexity. At the core of BUFFEST is an event-based buffer emulator module for detailed analysis of clients' buffer levels throughout a streaming session, as well as for automated training and evaluation of online packet-level classifiers. We then present example results using simple threshold-based classifiers and machine learning classifiers that only use TCP/IP packet-level information. Our results are encouraging and show that BUFFEST can distinguish streaming clients with low buffer conditions from clients with significant buffer margin during a session even when HTTPS is used.

    Place, publisher, year, edition, pages
    ACM, 2017
    Keywords
    Buffer condition estimation, HTTP-based adaptive streaming, HTTPS, Real-time requirements
    National Category
    Computer and Information Sciences
    Identifiers
    urn:nbn:se:liu:diva-140913 (URN)10.1145/3083187.3083193 (DOI)978-1-4503-5002-0 (ISBN)
    Conference
    8th ACM Conference on Multimedia Systems, June 20-23, 2017, Taipei, Taiwan
    Available from: 2017-09-15 Created: 2017-09-15 Last updated: 2018-02-06
    4. Empowering the creative user: personalized HTTP-based adaptive streaming of multi-path nonlinear video
    Open this publication in new window or tab >>Empowering the creative user: personalized HTTP-based adaptive streaming of multi-path nonlinear video
    Show others...
    2013 (English)In: FhMN '13 Proceedings of the 2013 ACM SIGCOMM workshop on Future human-centric multimedia networking, New York, USA: Association for Computing Machinery (ACM), 2013, p. 53-58Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper presents the design, implementation, and validation of a novel system that supports streaming and playout of personalized, multi-path, nonlinear video. In contrast to regular video, in which the file content is played sequentially, our design allows multiple nonlinear video sequences of the underlying (linear) video to be stitched together and played in any personalized order, and clients can be provided multiple path choices. The design combines the ideas of HTTP-based adaptive streaming (HAS) and multi-path nonlinear video. Personalization of the content is achieved with the use of a customized metafile, which is downloaded separately from the underlying media and the manifest file that defines the HAS structure. An extension to the user interface allows path choices to be presented to and made by the user. Novel buffer management and prefetching policies are used to ensure seamless uninterrupted playback regardless of client path choices, even under scenarios in which clients defer their choices until the last possible moment. Our solution allows creative home users to easily create their own multi-path nonlinear video, opening the door to an endless possibility of new opportunities and media forms.

    Place, publisher, year, edition, pages
    New York, USA: Association for Computing Machinery (ACM), 2013
    Keywords
    HTTP-based adaptive streaming, Multi-path video, Nonlinear video, Seamless playback
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-96695 (URN)10.1145/2491172.2491183 (DOI)978-1-4503-2183-9 (ISBN)
    Conference
    ACM SIGCOMM 2013, Hong Kong, China, 12-16 August 2013
    Note

    Nominated as the Best Paper in the 2013 ACM SIGCOMM workshop on Future human-centric Multimedia Networking (FhMN)

    Available from: 2013-08-23 Created: 2013-08-23 Last updated: 2018-02-06Bibliographically approved
    5. Quality-adaptive prefetching for interactive branched video using HTTP-based Adaptive Streaming
    Open this publication in new window or tab >>Quality-adaptive prefetching for interactive branched video using HTTP-based Adaptive Streaming
    Show others...
    2014 (English)In: MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia, Association for Computing Machinery, Inc , 2014, p. 317-326Conference paper, Published paper (Refereed)
    Abstract [en]

    Interactive branched video that allows users to select their own paths through the video, provides creative content designers with great personalization opportunities; however, such video also introduces significant new challenges for the system developer. For example, without careful prefetching and buffer management, the use of multiple alternative playback paths can easily result in playback interruptions. In this paper, we present a full implementation of an interactive branched video player using HTTP-based Adaptive Streaming (HAS) that provides seamless playback even when the users defer their branch path choices to the last possible moment. Our design includes optimized prefetching policies that we derive under a simple optimization framework, effective buffer management of prefetched data, and the use of parallel TCP connections to achieve efficient buffer workahead. Through performance evaluation under a wide range of scenarios, we show that our optimized policies can effectively prefetch data of carefully selected qualities along multiple alternative paths such as to ensure seamless playback, offering users a pleasant viewing experience without playback interruptions.

    Place, publisher, year, edition, pages
    Association for Computing Machinery, Inc, 2014
    Series
    MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia
    Keywords
    Branched video; HTTP-based Adaptive Streaming (HAS); Multipath/nonlinear streaming; Seamless playback
    National Category
    Computer and Information Sciences
    Identifiers
    urn:nbn:se:liu:diva-116449 (URN)10.1145/2647868.2654951 (DOI)2-s2.0-84913597570 (Scopus ID)9781450330633 (ISBN)
    Conference
    2014 ACM Conference on Multimedia, MM 2014
    Available from: 2015-03-27 Created: 2015-03-26 Last updated: 2018-02-06
    6. Optimized Adaptive Streaming of Multi-video Stream Bundles
    Open this publication in new window or tab >>Optimized Adaptive Streaming of Multi-video Stream Bundles
    2017 (English)In: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 19, no 7, p. 1637-1653Article in journal (Refereed) Published
    Abstract [en]

    In contrast to traditional video, multi-view video streaming allows viewers to interactively switch among multiple perspectives provided by different cameras. One approach to achieve such a service is to encode the video from all of the cameras into a single stream, but this has the disadvantage that only a portion of the received video data will be used, namely that required for the selected view at each point in time. In this paper, we introduce the concept of a multi-video stream bundle that consists of multiple parallel video streams that are synchronized in time, each providing the video from a different camera capturing the same event or movie. For delivery we leverage the adaptive features and time-based chunking of HTTP-based adaptive streaming, but now employing adaptation in both content and rate. Users are able to change their viewpoint on-demand and the client player adapts the rate at which data are retrieved from each stream based on the users current view, the probabilities of switching to other views, and the users current bandwidth conditions. A crucial component of such a system is the prefetching policy. For this we present an optimization model as well as a simpler heuristic that can balance the playback quality and the probability of playback interruptions. After analytically and numerically characterizing the optimal solution, we present a prototype implementation and sample results. Our prefetching and buffer management solution is shown to provide close to seamless playback switching when there is sufficient bandwidth to prefetch the parallel streams.

    Place, publisher, year, edition, pages
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
    Keywords
    HTTP-based adaptive streaming (HAS); multi-view video streaming; multi-video stream bundles; optimized prefetching; seamless stream switching
    National Category
    Telecommunications
    Identifiers
    urn:nbn:se:liu:diva-139270 (URN)10.1109/TMM.2017.2673412 (DOI)000404061800019 ()
    Note

    Funding Agencies|Swedish Research Council (VR); Center for Industrial Information Technology (CENIIT); Natural Sciences and Engineering Research Council of Canada

    Available from: 2017-07-07 Created: 2017-07-07 Last updated: 2018-02-06
  • 7.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Bergström, Patrik
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Empowering the Creative User: Personalized HTTP-based Adaptive Streaming of Multi-path Nonlinear Video2013In: Computer communication review, ISSN 0146-4833, E-ISSN 1943-5819, Vol. 43, no 4, p. 591-596Article in journal (Refereed)
    Abstract [en]

    This paper presents the design, implementation, and validation of a novel system that supports streaming and playout of personalized, multi-path, nonlinear video. In contrast to regular video, in which the file content is played sequentially, our design allows multiple nonlinear video sequences of the underlying (linear) video to be stitched together and played in any personalized order, and clients can be provided multiple path choices. The design combines the ideas of HTTP-based adaptive streaming (HAS) and multi-path nonlinear video. Personalization of the content is achieved with the use of a customized metafile, which is downloaded separately from the underlying media and the manifest file that defines the HAS structure. An extension to the user interface allows path choices to be presented to and made by the user. Novel buffer management and prefetching policies are used to ensure seamless uninterrupted playback regardless of client path choices, even under scenarios in which clients defer their choices until the last possible moment. Our solution allows creative home users to easily create their own multi-path nonlinear video, opening the door to an endless possibility of new opportunities and media forms.

  • 8.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Bergström, Patrik
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, Derek
    University of Saskatchewan.
    Mahanti, Anirban
    NICTA, Sydney, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Empowering the creative user: personalized HTTP-based adaptive streaming of multi-path nonlinear video2013In: FhMN '13 Proceedings of the 2013 ACM SIGCOMM workshop on Future human-centric multimedia networking, New York, USA: Association for Computing Machinery (ACM), 2013, p. 53-58Conference paper (Refereed)
    Abstract [en]

    This paper presents the design, implementation, and validation of a novel system that supports streaming and playout of personalized, multi-path, nonlinear video. In contrast to regular video, in which the file content is played sequentially, our design allows multiple nonlinear video sequences of the underlying (linear) video to be stitched together and played in any personalized order, and clients can be provided multiple path choices. The design combines the ideas of HTTP-based adaptive streaming (HAS) and multi-path nonlinear video. Personalization of the content is achieved with the use of a customized metafile, which is downloaded separately from the underlying media and the manifest file that defines the HAS structure. An extension to the user interface allows path choices to be presented to and made by the user. Novel buffer management and prefetching policies are used to ensure seamless uninterrupted playback regardless of client path choices, even under scenarios in which clients defer their choices until the last possible moment. Our solution allows creative home users to easily create their own multi-path nonlinear video, opening the door to an endless possibility of new opportunities and media forms.

  • 9.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, D.
    University of of Saskatchewan, Canada.
    Mahanti, A.
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Quality-adaptive prefetching for interactive branched video using HTTP-based Adaptive Streaming2014In: MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia, Association for Computing Machinery, Inc , 2014, p. 317-326Conference paper (Refereed)
    Abstract [en]

    Interactive branched video that allows users to select their own paths through the video, provides creative content designers with great personalization opportunities; however, such video also introduces significant new challenges for the system developer. For example, without careful prefetching and buffer management, the use of multiple alternative playback paths can easily result in playback interruptions. In this paper, we present a full implementation of an interactive branched video player using HTTP-based Adaptive Streaming (HAS) that provides seamless playback even when the users defer their branch path choices to the last possible moment. Our design includes optimized prefetching policies that we derive under a simple optimization framework, effective buffer management of prefetched data, and the use of parallel TCP connections to achieve efficient buffer workahead. Through performance evaluation under a wide range of scenarios, we show that our optimized policies can effectively prefetch data of carefully selected qualities along multiple alternative paths such as to ensure seamless playback, offering users a pleasant viewing experience without playback interruptions.

  • 10.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Bandwidth-aware Prefetching for Proactive Multi-video Preloading and Improved HAS Performance2015In: Proceedings of the ACM International Conference on Multimedia (ACM Multimedia), New York, USA: Association for Computing Machinery (ACM), 2015, p. 551-560Conference paper (Refereed)
    Abstract [en]

    This paper considers the problem of providing users playing one streaming video the option of instantaneous and seamless playback of alternative videos. Recommendation systems can easily provide a list of alternative videos, but there is little research on how to best eliminate the startup time for these alternative videos. The problem is motivated by services that want to retain increasingly impatient users, who frequently watch the beginning of multiple videos, before viewing a video to the end. We present the design, implementation, and evaluation of an HTTP-based Adaptive Streaming (HAS) solution that provides careful prefetching and buffer management. We also present the design and evaluation of three fundamental policy classes that provide different tradeoffs between how aggressively new alternative videos are prefetched versus the importance of ensuring high playback quality. We show that our solution allows us to reduce the startup times of alternative videos by an order of magnitude and effectively adapt the quality such as to ensure the highest possible playback quality of the video being viewed. By improving the channel utilization we also address the discrimination problem that HAS clients often suffer from, allowing us to in some cases simultaneously improve the playback quality of the video being viewed and provide the value-added service of allowing instantaneous playback of the prefetched alternative videos.

  • 11.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Helping Hand or Hidden Hurdle: Proxy-assisted HTTP-based Adaptive Streaming Performance2013In: Modeling, Analysis & Simulation of Computer and Telecommunication Systems (MASCOTS), 2013 IEEE 21st International Symposium, IEEE , 2013, p. 182-191Conference paper (Refereed)
    Abstract [en]

    HTTP-based Adaptive Streaming (HAS) has become a widely-used video delivery technology. Use of HTTP enables relatively easy firewall/NAT traversal and content caching. While caching is an important aspect of HAS, there is not much public research on the performance impact proxies and their policies have on HAS. In this paper we build an experimental framework using open source Squid proxies and the most recent Open Source Media Framework (OSMF). A range of content-aware policies can be implemented in the proxies and tested, while the player software can be instrumented to measure performance as seen at the client. Using this framework, the paper makes three main contributions. First, we present a scenario-based performance evaluation of the latest version of the OSMF player. Second, we quantify the benefits using different proxy-assisted solutions, including basic best effort policies and more advanced content quality aware prefetching policies. Finally, we present and evaluate a cooperative framework in which clients and proxies share information to improve performance. In general, the bottleneck location and network conditions play central roles in which policy choices are most advantageous, as they significantly impact the relative performance differences between policy classes. We conclude that careful design and policy selection is important when trying to enhance HAS performance using proxy assistance.

  • 12.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Halepovic, Emir
    ATandT Labs Res, NJ USA.
    Slow but Steady: Cap-based Client-Network Interaction for Improved Streaming Experience2018In: 2018 IEEE/ACM 26TH INTERNATIONAL SYMPOSIUM ON QUALITY OF SERVICE (IWQOS), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    Due to widespread popularity of streaming services, many streaming clients typically compete over bottleneck links for their own bandwidth share. However, in such environments, the rate adaptation algorithms used by modern streaming clients often result in instability and unfairness, which negatively affects the playback experience. In addition, mobile clients often waste bandwidth by trying to stream excessively high video bitrates. We present and evaluate a cap-based framework in which the network and clients cooperate to improve the overall Quality of Experience (QoE). First, to motivate the framework, we conduct a comprehensive study using the lab setup showing that a fixed rate cap comes with both benefits (e.g., data savings, improved stability and fairness) and drawbacks (e.g., higher startup times and slower recovery after stalls). To address the drawbacks while keeping the benefits, we then introduce and evaluate a framework that includes (i) buffer-aware rate caps in which the network temporarily boosts the rate cap of clients during video startup and under low buffer conditions, and (ii) boost-aware client-side adaptation algorithms that optimize the bitrate selection during the boost periods. Combined with information sharing between the network and clients, these mechanisms are shown to improve QoE, while reducing wasted bandwidth.

  • 13.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Halepovic, Emir
    AT&T Labs, USA.
    Petajan, Eric
    AT&T Labs, USA.
    BUFFEST: Predicting Buffer Conditions and Real-time Requirements of HTTP(S) Adaptive Streaming Clients2017In: MMSys’17, Proceedings of the 8th ACM on Multimedia Systems Conference, ACM , 2017, p. 76-87Conference paper (Refereed)
    Abstract [en]

    Stalls during video playback are perhaps the most important indicator of a client's viewing experience. To provide the best possible service, a proactive network operator may therefore want to know the buffer conditions of streaming clients and use this information to help avoid stalls due to empty buffers. However, estimation of clients' buffer conditions is complicated by most streaming services being rate-adaptive, and many of them also encrypted. Rate adaptation reduces the correlation between network throughput and client buffer conditions. Usage of HTTPS prevents operators from observing information related to video chunk requests, such as indications of rate adaptation or other HTTP-level information.; AB@This paper presents BUFFEST, a novel classification framework that can be used to classify and predict streaming clients' buffer conditions from both HTTP and HTTPS traffic. To illustrate the tradeoffs between prediction accuracy and the available information used by classifiers, we design and evaluate classifiers of different complexity. At the core of BUFFEST is an event-based buffer emulator module for detailed analysis of clients' buffer levels throughout a streaming session, as well as for automated training and evaluation of online packet-level classifiers. We then present example results using simple threshold-based classifiers and machine learning classifiers that only use TCP/IP packet-level information. Our results are encouraging and show that BUFFEST can distinguish streaming clients with low buffer conditions from clients with significant buffer margin during a session even when HTTPS is used.

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