[7] | Michael Grafl, Christian Timmerer, Representation Switch Smoothing for Adaptive HTTP Streaming, In Proceedings of the 4th International Workshop on Perceptual Quality of Systems (PQS 2013) (Raimund Schatz, Tobias Hoßfeld, eds.), FTW, Vienna, Austria, pp. 178-183, 2013.
[bib] [pdf] [abstract]
Abstract: When an adaptive media streaming system has to switch from one representation of the content to another, the switch causes viewer distraction. We introduce the concept of representation switch smoothing for alleviating the distraction and improving the overall quality of experience. As adaptive HTTP streaming systems typically deploy video buffers on the client side, the adaptation decision is known far enough ahead of playout time to perform a seamless transition between quality representations. We discuss implementation considerations for an adaptive HTTP streaming system with scalable video coding, present a subjective evaluation of the proposed approach, and identify factors that influence how smooth transitions are perceived.
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[6] | Michael Grafl, Christian Timmerer, Hermann Hellwagner, Wael Cherif, Daniel Negru, Stefano Battista, Scalable Video Coding Guidelines and Performance Evaluations for Adaptive Media Delivery of High Definition Content, In Proceedings of the 18th IEEE Symposium on Computers and Communication (ISCC 2013) (Christos Douligeris, Sven Gotovac, Milan Vojnović, eds.), IEEE, Los Alamitos, CA, USA, pp. 6, 2013.
[bib] [pdf] [abstract]
Abstract: Scalability within media coding allows for content adaptation towards heterogeneous user contexts and enables in-network adaptation. However, there is no straightforward solution how to encode the content in a scalable way while maximizing rate-distortion performance. In this paper we provide encoding guidelines for scalable video coding based on a survey of media streaming industry solutions and a comprehensive performance evaluation using four state of the art scalable video codecs with a focus on high-definition content (1080p).
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[5] | Michael Grafl, Christian Timmerer, Hermann Hellwagner, Wael Cherif, Adlen Ksentini, Hybrid Scalable Video Coding for HTTP-based Adaptive Media Streaming with High-Definition Content, In Computer Communications, Elsevier, Amsterdam, Netherlands, pp. 11, 2013.
[bib] [abstract]
Abstract: Scalable Video Coding (SVC) in media streaming enables dynamic adaptation based on device capabilities and network conditions. In this paper, we investigate deployment options of SVC for Dynamic Adaptive Streaming over HTTP (DASH) with a special focus on scalability options, which are relevant for dynamic adaptation, especially in wireless and mobile environments. We establish encoding recommendations and evaluate the performance of SVC with respect to spatial and quality scalability options and compare it to non-scalable Advanced Video Coding (AVC). Performance evaluations are performed for various encoder implementations with high-definition (1080p) content. We show that a hybrid approach with multiple independent SVC bitstreams can have advantages in storage requirements at comparable rate-distortion performance.
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[4] | Michael Grafl, Christian Timmerer, Hermann Hellwagner, George Xilouris, Georgios Gardikis, Daniele Renzi, Stefano Battista, Eugen Borcoci, Daniel Negru, Scalable Media Coding enabling Content-Aware Networking, In IEEE MultiMedia, IEEE Computer Society, vol. 20, no. 2, Los Alamitos, CA, USA, pp. 30-41, 2013.
[bib] [doi] [pdf] [abstract]
Abstract: Given that multimedia services are becoming increasingly popular, they are expected to play a dominant role for the Future Internet. In this context, it is essential that Content-Aware Networking (CAN) architectures, as envisaged in the frame of the Future Internet, explicitly address the efficient delivery and processing of multimedia content. This article proposes adopting a content-aware approach into the network infrastructure, thus making it capable of identifying, processing, and manipulating (i.e., adapting, caching, etc.) media streams and objects in real time towards Quality of Service/Experience (QoS/QoE) maximization. Our proposal is built upon the exploitation of scalable media coding technologies within such a content-aware networking environment and is discussed based on four representative use cases for media delivery (unicast, multicast, peer-to-peer, and adaptive HTTP streaming) and with respect to a selection of CAN challenges, specifically flow processing, caching/buffering, and QoS/QoE management.
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[3] | Georgios Gardikis, Evangelos Pallis, Michael Grafl, Media-Aware Networks in Future Internet Media, Chapter in 3D Future Internet Media (Ahmet Kondoz, Tasos Dagiuklas, eds.), Springer Science+Business Media, LLC, New York, pp. 6, 2013.
[bib][url] [doi] [abstract]
Abstract: Multimedia (especially video) services constitute a dominant and ever increasing portion of the global Internet traffic, while they are expected to also play a major role in the Future Internet scene. In order to address this reality in the networking domain, a promising perspective is to gradually shift from the current, service-unaware, best-effort nature of IP networks into a network logic which is service-aware – and, in specific, media-aware. This chapter discusses how media-awareness can be introduced in the networking domain in a way which is both feasible and scalable, leveraging at the same time state-of-the-art technologies in video representations, such as Scalable Video Coding (SVC) and Dynamic Adaptive Streaming over HTTP (DASH).
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[2] | Barry Crabtree, Tim Stevens, Brahin Allan, Stefan Lederer, Daniel Posch, Christopher Mueller, Christian Timmerer, Video Adaptation in Limited or Zero Network Coverage, In CCNxConn 2013 (Priya Mahadevan, ed.), PARC, Palo Alto, pp. 1-2, 2013.
[bib][url] [pdf] [abstract]
Abstract: This paper shows how adaptive streaming and on-device caching can be used to provide an always available video service. A DASH client has been extended to deal with periods of zero network connectivity, and seamlessly works in conjunction with CCN to provide local storage that is intelligently updated to provide an improved quality of experience.
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[1] | Claudio Alberti, Daniele Renzi, Christian Timmerer, Christopher Mueller, Stefan Lederer, Stefano Battista, Marco Mattavelli, Automated QoE Evaluation of Dynamic Adaptive Streaming over HTTP, In Proceedings of the 5th International Workshop on Quality of Multimedia Experience (QoMEX'13) (Christian Timmerer, Patrick Le Callet, Martin Varela, Stefan Winkler, Tiago Falk, eds.), IEEE, Los Alamitos, CA, USA, pp. 58-63, 2013.
[bib] [pdf] [abstract]
Abstract: Dynamic Adaptive Streaming over HTTP (DASH) is referred to as a multimedia streaming standard to deliver high quality multimedia content over the Internet using conventional HTTP Web servers. As a fundamental feature, it enables automatic switching of quality levels according to network conditions, user requirements, and expectations. Currently, the proposed adaptation schemes for HTTP streaming mostly rely on throughput measurements and/or buffer-related metrics, such as buffer exhaustion and levels. In this paper, we propose to enhance the DASH adaptation logic by feeding it with additional information from our evaluation of the users' perception approximating the user- perceived quality of video playback. The proposed model aims at conveniently combining TCP-, buffer-, and media content-related metrics as well as user requirements and expectations to be used as an input for the DASH adaptation logic. Experiments have demonstrated that the chosen model enhances the capability of the adaptation logic to select the optimal video quality level. Finally, we integrated all our findings into a real DASH system with QoE monitoring capabilities.
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