[131] | Hermann Hellwagner, Robert Kuschnig, Thomas Stütz, Andreas Uhl, Efficient In-Network Adaptation of Encrypted H.264/SVC Content, In Journal on Signal Processing: Image Communication, Elsevier B.V., vol. 24, no. 9, Amsterdam, pp. 740-758, 2009.
[bib] [pdf] [abstract]
Abstract: This paper addresses the efficient adaptation of encrypted scalable video content (H.264/SVC). RTP-based in-network adaptation schemes on a media aware network element (MANE) in an IPTV and VoD scenario are considered. Two basic alternatives to implement encryption and adaptation of H.264/SVC content are investigated: (i) full, format-independent encryption making use of Secure RTP (SRTP); (ii) SVC-specific encryption that leaves the metadata relevant for adaptation (NAL unit headers) unencrypted. The SRTP-based scheme (i) is straightforward to deploy, but requires the MANE to be in the security context of the delivery, i.e., to be a trusted node. For adaptation, the content needs to be decrypted, scaled, and re-encrypted. The SVC-specific approach (ii) enables both full and selective encryption, e.g., of the base layer only. SVC-specific encryption is based on own previous work, which is substantially extended and detailed in this paper. The adaptation MANE can now be an untrusted node; adaptation becomes a low-complexity process, avoiding full decryption and re-encryption of the content. This paper presents the first experimental comparison of these two approaches and evaluates whether multimedia-specific encryption can lead to performance and application benefits. Potential security threats and security properties of the two approaches in the IPTV and VoD scenario are elementarily analyzed. In terms of runtime performance on the MANE our SVC-specific encryption scheme significantly outperforms the SRTP-based approach. SVC-specific encryption is also superior in terms of induced end-to-end delays. The performance can even be improved by selective application of the SVC-specific encryption scheme. The results indicate that efficient adaptation of SVC-encrypted content on low-end, untrusted network devices is feasible.
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[130] | Alois Ferscha, Hermann Hellwagner, Christa Neuper, Wolfgang Pree, Zukunft der Informatik, In Informatik macht Zukunft - Zukunft macht Informatik (Gerhard Chroust, Hans-Peter Moessenboeck, eds.), Oesterreichische Computer Gesellschaft, Wien, pp. 48-51, 2009.
[bib] |
[129] | Michael Eberhard, Christian Timmerer, Emanuele Quacchio, Hermann Hellwagner, An Interoperable Delivery Framework for Scalable Media Resources, In IEEE Wireless Communications, IEEE, vol. Oktober 2009, no. Vol. 16, No. 5, Los Alamitos, CA, USA, pp. 58-63, 2009.
[bib] [pdf] [abstract]
Abstract: In this paper, an interoperable framework for the delivery of scalable media resources, e.g., in the standardized Scalable Video Coding (SVC) format, is presented. The framework provides support for Video on Demand (VoD) as well as multicast streaming and performs an efficient, generic, and interoperable adaptation of the streamed content based on MPEG-21 Digital Item Adaptation (DIA). The server as well as the clients of the streaming framework implement the MPEG Extensible Middleware (MXM) and utilize the MPEG Query Format (MPQF) for querying the available media resources. The framework has been fully integrated into the VLC media player. The architecture for both, VoD and multicast is presented in detail. Finally, a comparison in terms of performance of the generic MPEG-21 metadata-based adaptation approach to an SVC-specific adaptation approach is provided.
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[128] | Michael Eberhard, Christian Timmerer, Hermann Hellwagner, A Layered Piece-Picking Algorithm for Peer-to-Peer Networks, In STreaming Day ’09 Proceedings (Marko Raggio, Fabrizio Rovati, eds.), NA, NA, pp. n.a., 2009.
[bib] [abstract]
Abstract: The streaming of multimedia content over Peer-to-Peer (P2P) networks is nowadays a well appreciated concept, as it helps distributing content to a great number of users and additionally reduces the server costs for providing the content. As the users of P2P networks often have different bandwidth connections and terminals, the same content is usually provided in different qualities. Although such a provision of the same content in different qualities helps to satisfy all users, it makes the sharing process less efficient. Users that are interested in the content in a specific quality can only exchange pieces with those users that are interested in the same content and the same quality. Thus, layered video coding, which provides different qualities within one bitstream, is especially well suited for P2P distribution. If the layered content is provided once in the best quality, all peers interested in this content can at least exchange the base layer, plus the enhancement layers they are interested in with those peers that have them available.
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[127] | Roland Tusch, Michael Jakab, Julius Köpke, Armin Krätschmer, Michael Kropfberger, Sigrid Kuchler, Michael Ofner, Hermann Hellwagner, Laszlo Böszörmenyi, Context-Aware UPnP-AV Services for Adaptive Home Multimedia Systems, In International Journal of Digital Multimedia Broadcasting, Hindawi Publishing Corporation, vol. Vol. 2008, Cairo, pp. 12, 2008.
[bib][url] [doi] [pdf] [abstract]
Abstract: One possibility to provide mobile multimedia in domestic multimedia systems is the use of Universal Plug and Play Audio Visual (UPnP-AV) devices. In a standard UPnP-AV scenario, multimedia content provided by a Media Server device is streamed to Media Renderer devices by the initiation of a Control Point. However, there is no provisioning of context-aware multimedia content customization. This paper presents an enhancement of standard UPnP-AV services for home multimedia environments regarding context awareness. It comes up with context profile definitions, shows how this context information can be queried from the Media Renderers, and illustrates how a Control Point can use this information to tailor a media stream from the Media Server to one or more Media Renderers. Moreover, since a standard Control Point implementation only queries one Media Server at a time, there is no global view on the content of all Media Servers in the UPnP-AV network. This paper also presents an approach of multimedia content integration on the Media Server side that provides fast search for content on the network. Finally, a number of performance measurements show the overhead costs of our enhancements to UPnP-AV in order to achieve the benefits.
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[126] | Christian Timmerer, Michael Ransburg, Ingo Kofler, Hermann Hellwagner, Pedro Souto, Maria Andrade, Pedro Carvalho, Helder Castro, Mamadou Sidibe, Ahmed Mehaoua, Li Fang, Adam Lindsay, Michael Mackay, Artur Lugmayr, Bernhard Feiten, An Integrated Management Supervisor for End-to-End Management of Heterogeneous Contents, Networks, and Terminals enabling Quality of Service, In Proceedings of the 2nd European Symposium on Mobile Media Delivery (EUMOB) (Tapio Frantti, Jyrki Huusko, eds.), ACM, New York, NY, USA, pp. 6, 2008.
[bib] [pdf] [abstract]
Abstract: End-to-end support for Quality of Service (QoS) has been broadly discussed in the literature. Many technologies have been proposed, each focusing on specific aspects for providing QoS guarantees to the end user. However, the integrated management of the end-to-end chain preserving QoS in heterogeneous environments is still a significant issue and insufficiently addressed to date. In this paper we propose an integrated management supervisor that takes into account the requirements from all stakeholders along the multimedia content delivery chain and provides an end-to-end management solution enabling QoS to the end user. This architecture and the subsystems that can be distributed along the end-to-end chain are detailed in this paper.
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[125] | Christian Timmerer, Hermann Hellwagner, Das MPEG-21 Multimedia Framework, In Informatik Spektrum, Springer, vol. 31, no. 6, Berlin, Heidelberg, New York, pp. 576-579, 2008.
[bib] |
[124] | Christian Timmerer, Maria Teresa Andrade, Pedro Carvalho, Davide Rogai, Giovanni Cordara, The Semantics of MPEG-21 Digital Items Revisited, In Proceedings of ACM Multimedia 2008 2nd International Workshop on the Many Faces of Multimedia Semantics (Farshad Fotouhi, William I Grosky, Peter Stanchev, eds.), ACM, New York, USA, pp. 17-23, 2008.
[bib] [doi] [pdf] [abstract]
Abstract: The MPEG-21 standard forms a comprehensive multimedia framework covering the entire multimedia distribution chain. In particular, it provides a flexible approach to represent, process, and transact complex multimedia objects which are referred to as Digital Items (DIs). DIs can be quite generic, independent of the application domain, and can encompass a diversity of media resources and metadata. This flexibility has an impact on the level of interoperability between systems and applications, since not all the functionality needs to be implemented. Furthermore, additional semantic rules may be implemented through the processing of the Digital Item which is possibly driven by proprietary metadata. This jeopardizes interoperability and consequently raises barriers to the successful achievement of augmented and transparent use of multimedia resources. In this context, we have investigated and evaluated the interoperability at the semantic level of Digital Items throughout the automated production, delivery and consumption of complex multimedia resources in heterogeneous environments. This paper describes the studies conducted, the experiments performed, and the conclusions reached towards that goal.
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[123] | Christian Timmerer, Hermann Hellwagner, MPEG-21 Multimedia Framework, Chapter in Encyclopedia of Multimedia (Borko Furht, ed.), Springer, Berlin, Heidelberg, New York, pp. 463-469, 2008.
[bib] [pdf] |
[122] | Christian Timmerer, Anthony Vetro, Hermann Hellwagner, MPEG-21 Digital Item Adaptation, Chapter in Encyclopedia of Multimedia (Borko Furht, ed.), Springer, Berlin, Heidelberg, New York, pp. 457-463, 2008.
[bib] [pdf] |
[121] | Christian Timmerer, Multimedia Adaptation Decision-Taking, Chapter in Encyclopedia of Multimedia (Borko Furht, ed.), Springer, Berlin, Heidelberg, New York, pp. 485-487, 2008.
[bib] [pdf] [abstract]
Abstract: Multimedia adaptation decision-taking is referred to as the process of finding the optimal parameter settings for (multiple, possibly in series connected) multimedia content adaptation engines given the properties, characteristics, and capabilities of the content and the context in which it will be processed.
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[120] | Christian Timmerer, Michael Ransburg, Hermann Hellwagner, Generic Multimedia Content Adaptation, Chapter in Encyclopedia of Multimedia (Borko Furht, ed.), Springer, Berlin, Heidelberg, New York, pp. 263-271, 2008.
[bib] [pdf] |
[119] | Christian Timmerer, Generic adaptation of scalable multimedia resources, VDM Verlag Dr. Müller, Saarbrücken, Germany, pp. 162, 2008.
[bib] |
[118] | Mamadou Sidibe, Harilaos Koumaras, Ingo Kofler, Ahmed Mehaoua, Anastasios Kourtis, Christian Timmerer, A novel monitoring architecture for media services adaptation based on network QoS to perceived QoS mapping, In Journal on Signal, Image and Video Processing, Springer, vol. 2, no. 4, London, United Kingdom, pp. 307-320, 2008.
[bib] [doi] [pdf] [abstract]
Abstract: One of the future visions of multimedia networking is the provision of multimedia content at a variety of quality and price levels. Of the many approaches to this issue, one of the most predominant techniques is the concept of Perceived Quality of Service (PQoS), which extends the traditional engineering-based QoS concept to the perceptual satisfaction that the user receives from the reception of multimedia content. In this context, PQoS monitoring is becoming crucial to media service providers (SPs) for providing not only quantified PQoS-based services, but also service assurance based on multimedia content adaptation across heterogeneous networks. This work proposes a novel cross-layer monitoring architecture that utilizes a new Network QoS (NQoS) to PQoS mapping framework at the application level. The resulting QoS monitoring should allow the content delivery system to take sophisticated actions for real time media content adaptation, and aims to provide perceived service performance verification with respect to the QoS guarantees that have been specified in contractual agreements between providers and end-users. A subsequent performance evaluation of the proposed model conducted using a real test-bed environment demonstrates both the accuracy and feasibility of the network level measurements, the NQoS to PQoS mapping and the overall feasibility of the proposed end-to-end monitoring solution.
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[117] | Bernhard Reiterer, Cyril Concolato, Janine Lachner, Jean Le Feuvre, Jean-Claude Moissinac, Stefano Lenzi, Stefano Chessa, Enrique Fernández Ferrá, Juan José González Menaya, Hermann Hellwagner, User-centric universal multimedia access in home networks, In The Visual Computer, International Journal of Computer Graphics, Springer, vol. 24, no. 7-9, Berlin, Heidelberg, New York, pp. 837-845, 2008.
[bib][url] [doi] [pdf] [abstract]
Abstract: Much research is currently being conducted towards Universal Multimedia Access, aiming at removing barriers that arise when multimedia content is to be consumed with more and more heterogeneous devices and over diverse networks. We argue that users should be put at the center of the research work to enable user-centric multimedia access. In this paper we present the requirements for a user-centric multimedia access system in a networked home environment. These requirements are easy access to available content repositories, context awareness, content adaptation and session migration. After showing the limits of state-of-the-art technologies, we present the architecture of a system which allows unified access to the home network content, automatically delivered to rendering devices close to the user, adapted according to the rendering device constraints, and which is also capable of session mobility.
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[116] | Michael Ransburg, Hubert Gressl, Hermann Hellwagner, Efficient Transformation of MPEG-21 Metadata for Codec-agnostic Adaptation in Real-time Streaming Scenarios, In 2008 Ninth International Workshop on Image Analysis for Multimedia Interactive Services (Hermann Hellwagner, Christian Timmerer, eds.), IEEE, Los Alamitos, CA, USA, pp. 143-146, 2008.
[bib][url] [pdf] [abstract]
Abstract: Scalable media contents, such as the new MPEG-4 Scalable Video Codec enable to easily retrieve different qualities of the media content by simply disregarding certain media segments. The MPEG-21-based codec-agnostic adaptation approach supports this concept by introducing an XMLbased Bitstream Syntax Description (BSD) which describes the different segments of a media content. Based on this BSD, an adaptation node can intelligently adapt any scalable media (i.e., remove specific media segments) without the need for codec-specific knowledge. The adaptation approach consists of 1) transforming this BSD and 2) adapting the media based on the transformed BSD. In this paper, we focus on the BSD transformation step and evaluate different mechanisms w.r.t. their transformation efficiency given several application scenarios. In particular, we compare the traditional stylesheet-based mechanisms with a novel mechanism based on regular expressions. We discuss both mechanisms in terms of their expressiveness, and propose how to actually employ regular expressions for codec-agnostic adaptation. Finally, we quantitatively evaluate these mechanisms in different adaptation scenarios, which vary in the size and number of required BSD units
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[115] | Michael Ransburg, Christian Timmerer, Hermann Hellwagner, Dynamic and Distributed Multimedia Content Adaptation based on the MPEG-21 Multimedia Framework, In Multimedia Semantics: The role of Metadata (Mathias Lux, Michael Granitzer, Marc Spaniol, eds.), Springer, Berlin, Heidelberg, New York, pp. 3-24, 2008.
[bib] [doi] [abstract]
Abstract: Today, there are many technologies in place to establish an infrastructure for the delivery and consumption of multimedia content. In practice, however, several elements of such an infrastructure are often stand-alone systems and a big picture of how these elements relate to each other or even fit together is not available. Therefore, MPEG-21 aims to provide an open framework for interoperable multimedia delivery and consumption. This requirement for interoperability results in a great diversity of XML-based metadata, which describes the media data on semantic or syntactic levels, in order to make it more accessible to the user. This metadata can be of considerable size, which leads to problems in streaming scenarios. Other than media data, XML metadata has no concept of samples, thus inhibiting streamed (and timed) processing, which is natural for media data. In order to address the challenges and requirements resulting from this situation, the concept of streaming instructions is introduced. These streaming instructions facilitate the fragmentation of content-related metadata, the association of media and metadata fragments with each other, and the synchronized streaming and processing of those fragments. Based on these capabilities, a dynamic and distributed multimedia content adaptation framework can be built.
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[114] | Markus Quaritsch, Emil Stojanovski, Christian Bettstetter, Gerhard Friedrich, Hermann Hellwagner, Bernhard Rinner, Michael Hofbaur, Mubarak Shah, Collaborative Microdrones: Applications and Research Challenges, In Proceedings of the Second International Conference on Autonomic Computing and Communication Systems (ACM, ed.), ACM Press, New York, NY, USA, pp. 7, 2008.
[bib][url] [pdf] [abstract]
Abstract: Microdrones are small-scale unmanned aerial vehicles (UAVs) carrying payloads such as cameras and sensors. Such microdrones enable us to obtain a bird's eye view of the environment which is helpful in many applications such as environmental monitoring, surveillance or disaster management. This position paper reports on our recently launched project \collaborative microdrones" where we are developing a system for aerial imaging based on cooperating, wireless networked microdrones that can be used in disaster management applications. Several microdrones will y in formation over the area of interest and deliver sensor data which is fused, analyzed and delivered to the user in real-time. In this paper we brie y discuss applications for UAVs, present related projects, introduce our research focus and report on preliminary results.
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[113] | Martin Prangl, Ingo Kofler, Hermann Hellwagner, Towards QoS Improvements of TCP-based Media Delivery, In Proceedings of the 4th International Conference on Networking and Services (ICNS) (Jun Bi, Kim Chin, Cosmin Dini, Leo Lehmann, David C Pheanis, eds.), IEEE, Los Alamitos, CA, USA, pp. 188-193, 2008.
[bib] [doi] [pdf] [abstract]
Abstract: The amount of audiovisual data available on the Internet and thus of multimedia communication over today's networks is increasing at a rapid pace. Despite the availability of specific media transport protocols like RTP, most content providers make use of the well-established and reliable TCP protocol to deliver audiovisual content over the Internet. The reason is that TCP-based data delivery in general is much less complicated for the clients to be served and over today's networks traversed (including proxies and firewalls), than making use of UDP-based RTP connections. However, in case of network bandwidth fluctuations and packet losses, TCP-based media delivery may lead to annoying jerky playback at the client side, due to retransmissions and late arrival of media data. This papers deals with TCP-based perceptual QoS improvement mechanisms for increasing the media experience for the consumer under unstable network conditions. Our approach is based on media content adaptation (transcoding) to fit the actual network bandwidth continuously monitored by the sender. The proposed mechanisms are applied at the application level at the server side, leaving the existing TCP implementation untouched and therefore enabling transparent use of existing media players. An evaluation of a realistic use case is presented which underlines the efficency of our approach.
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[112] | Martin Prangl, Ingo Kofler, Hermann Hellwagner, An MPEG-21-driven Utility-based Multimedia Adaptation Decision Taking Web Service, In Proceedings of the 1st International Conference on Ambient Media and Systems (Ambi-sys) (Roger M Whitaker, Ben Liang, eds.), ICST, Brussels, Belgium, pp. 8, 2008.
[bib] [pdf] [abstract]
Abstract: Supporting transparent delivery and convenient use of multimedia content across a wide range of networks and devices is still a challenging task within the multimedia research community; Universal Multimedia Access (UMA) is a vision that has been pursued for quite some time. In multimedia frameworks, content adaptation is the core concept to make progress toward this goal. Most media adaptation engines targeting UMA scale the content w.r.t. terminal capabilities and network resource constraints and do not sufficiently consider end user preferences or even the utility of the adapted content for the user. Based on our previous work and the support of the MPEG-21 framework, we present a transparent solution to provide a content utility-aware adaptation decision for such utility-unaware multimedia frameworks. The idea is to outsource the challenging utility-aware adaptation decision taking task, which takes many factors into consideration and leads to a complex optimization problem. A realistic use case is adopted to show how related external multimedia frameworks can easily integrate and use our proposed adaptation decision taking Web Service.
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[111] | Phivos Mylonas, Hermann Hellwagner, Pablo Castells, Manolis Wallace, Signal, image and video processing (SIVP) special issue on “multimedia semantics, adaptation and personalization” Editorial, In Signal, Image and Video Processing, Springer, vol. 2/2008, no. 4, Berlin, Heidelberg, New York, pp. 287-288, 2008.
[bib][url] |
[110] | Michael Mackay, David Hutchison, Michael Ransburg, Hermann Hellwagner, Combined Adaptation and Caching of MPEG-4 SVC in Streaming Scenarios, In 2008 Ninth International Workshop on Image Analysis for Multimedia Interactive Services (Hermann Hellwagner, Christian Timmerer, eds.), IEEE, Los Alamitos, CA, USA, pp. 101-104, 2008.
[bib][url] [pdf] [abstract]
Abstract: A key objective of the ENTHRONE II Project is the ability to optimise the delivery of multimedia content to a wide group of heterogeneous users. One example of this is in the cooperative deployment of adaptation and caching functionality in the edge network. This hybrid approach makes it possible not only to store content locally, thus minimising the cost incurred through subsequent requests, but also to better serve heterogeneous groups of users by dynamically adapting the content to suit a wide range of terminal devices. In this paper, we describe and evaluate how the cooperative deployment of MPEG-21-based adaptation and caching of MPEG-4 SVC can result in improvements both in the quality of the content received at the user terminal and the resources consumed during the delivery
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[109] | Fernando López, Dietmar Jannach, José M Martínez, Christian Timmerer, Hermann Hellwagner, Narciso García, Multimedia Adaptation Decisions Modelled as Non-deterministic Operations, In 2008 Ninth International Workshop on Image Analysis for Multimedia Interactive Services (Hermann Hellwagner, Christian Timmerer, eds.), IEEE, Los Alamitos, CA, USA, pp. 46-49, 2008.
[bib][url] [pdf] [abstract]
Abstract: This paper describes how a multimedia adaptation framework can automatically decide the sequence of operations to be executed in order to adapt an MPEG-21 Digital Item to the MPEG-21 description of the usage environment in which it will be consumed. The main innovation of this work with respect to previous multimedia adaptation decision models is that in the proposed approach decisions can be made without knowing the exact behaviour of the operations that are going to be executed.
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[108] | Janine Lachner, Hermann Hellwagner, Information and Communication Systems for Mobile Emergency Response, In Information Systems and e-Business Technologies (Proc. 2nd International United Information Systems Conference, UNISCON 2008 (Roland Kaschek, Christian Kop, Claudia Steinberger, Günther Fliedl, eds.), Springer, Berlin, Heidelberg, New York, pp. 213-224, 2008.
[bib] [pdf] [abstract]
Abstract: This discussion paper attempts to propose emergency response and disaster management as worthwhile areas of applied research for the informa-tion system community. The typical requirements, entities and activities in-volved in specifically mobile emergency response operations are summarized. Recent research contributions in this area are exemplarily reviewed in order to give a deeper insight into the role and use of mobile information and communi-cation systems. Finally, the major challenges and research needs regarding in-formation systems are summarized, with a view to draw the attention of infor-mation systems researchers to this interesting and important field.
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[107] | Robert Kuschnig, Ingo Kofler, Michael Ransburg, Hermann Hellwagner, Design options and comparison of in-network H.264/SVC adaptation, In Journal of Visual Communication and Image Representation, Elsevier B.V., vol. 19, no. 8, Amsterdam, pp. 529-542, 2008.
[bib] [doi] [pdf] [abstract]
Abstract: This paper explores design options and evaluates implementations of in-network, RTP/RTSP based adaptation MANEs (Media Aware Network Elements) for H.264/SVC content streaming. The obvious technique to be employed by such an adaptation MANE is to perform SVC specific bitstream extraction or truncation. Another mechanism that can be used is description (metadata) driven, coding format independent adaptation based on generic Bitstream Syntax Descriptions (gBSD), as specified within MPEG-21 Digital Item Adaptation (DIA). Adaptation MANE architectures for both approaches are developed and presented, implemented in end-to-end streaming/adaptation prototype systems, and experimentally evaluated and compared. For the gBSD based solution, open issues like the granularity of bitstream descriptions and of bitstream adaptation, metadata overhead, metadata packetization and transport options, and error resilience in case of metadata losses, are addressed. The experimental results indicate that a simple SVC specific adaptation MANE does clearly outperform the gBSD based adaptation variants. Yet, the conceptual advantages of the description driven approach, like coding format independence and flexibility, may outweigh the performance drawbacks in specific applications.
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