% Categories: MMC & Type: Article % Encoding: utf-8 @Article{Timmerer2018b, author = {Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {MPEG column: 121st MPEG meeting in Gwangju, Korea}, year = {2018}, issn = {1947-4598}, month = mar, number = {1}, pages = {6:6--6:6}, volume = {10}, address = {New York, NY, USA}, doi = {10.1145/3178422.3178426}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3178422.3178426} } @Article{Timmerer2018a, author = {Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {MPEG Column: 120th MPEG Meeting in Macau, China}, year = {2018}, issn = {1947-4598}, month = jan, number = {3}, pages = {4:4--4:4}, volume = {9}, address = {New York, NY, USA}, doi = {10.1145/3210241.3210247}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3210241.3210247} } @Article{HH_martina_Dez, author = {Yanmaz, Evsen and Yahyanejad, Saeed and Rinner, Bernhard and Hellwagner, Hermann and Bettstetter, Christian}, journal = {Ad Hoc Networks}, title = {Drone networks: Communications, coordination, and sensing}, year = {2018}, month = {jan}, pages = {1-15}, volume = {68}, abstract = {Small drones are being utilized in monitoring, transport, safety and disaster management, and other domains. Envisioning that drones form autonomous networks incorporated into the air traffic, we describe a high-level architecture for the design of a collaborative aerial system consisting of drones with on-board sensors and embedded processing, coordination, and networking capabilities. We implement a multi-drone system consisting of quadcopters and demonstrate its potential in disaster assistance, search and rescue, and aerial monitoring. Furthermore, we illustrate design challenges and present potential solutions based on the lessons learned so far.}, address = {Amsterdam}, doi = {10.1016/j.adhoc.2017.09.001}, keywords = {Drones, Unmanned aerial vehicle networks, Wireless sensor networks, Vehicular communications, Cooperative aerial imaging, Search and rescue}, language = {EN}, publisher = {Elsevier}, url = {https://www.sciencedirect.com/science/article/pii/S1570870517301671} } @Article{HH_martina, author = {Pohl, Daniela and Bouchachia, Abdelhamid and Hellwagner, Hermann}, journal = {Expert Systems with Applications}, title = {Batch-based active learning: Application to social media data for crisis management}, year = {2018}, month = {mar}, pages = {232-244}, volume = {93}, abstract = {Classification of evolving data streams is a challenging task, which is suitably tackled with online learning approaches. Data is processed instantly requiring the learning machinery to (self-)adapt by adjusting its model. However for high velocity streams, it is usually difficult to obtain labeled samples to train the classification model. Hence, we propose a novel online batch-based active learning algorithm (OBAL) to perform the labeling. OBAL is developed for crisis management applications where data streams are generated by the social media community. OBAL is applied to discriminate relevant from irrelevant social media items. An emergency management user will be interactively queried to label chosen items. OBAL exploits the boundary items for which it is highly uncertain about their class and makes use of two classifiers: k-Nearest Neighbors (kNN) and Support Vector Machine (SVM). OBAL is equipped with a labeling budget and a set of uncertainty strategies to identify the items for labeling. An extensive analysis is carried out to show OBAL’s performance, the sensitivity of its parameters, and the contribution of the individual uncertainty strategies. Two types of datasets are used: synthetic and social media datasets related to crises. The empirical results illustrate that OBAL has a very good discrimination power.}, address = {Amsterdam}, doi = {10.1016/j.eswa.2017.10.026}, language = {EN}, publisher = {Elsevier Ltd.}, url = {http://www.sciencedirect.com/science/article/pii/S095741741730708X} } @Article{Zabrovskiy2017a, author = {Zabrovskiy, Anatoliy and Petrov, Evgeny and Kuzmin, Evgeny and Timmerer, Christian}, journal = {arXiv.org [cs.MM]}, title = {Evaluation of the Performance of Adaptive {HTTP} Streaming Systems}, year = {2017}, month = {oct}, pages = {7}, volume = {abs/1710.02459}, abstract = {Adaptive video streaming over HTTP is becoming omnipresent in our daily life. In the past, dozens of research papers have proposed novel approaches to address different aspects of adaptive streaming and a decent amount of player implementations (commercial and open source) are available. However, state of the art evaluations are sometimes superficial as many proposals only investigate a certain aspect of the problem or focus on a specific platform – player implementations used in actual services are rarely considered. HTML5 is now available on many platforms and foster the deployment of adaptive media streaming applications. We propose a common evaluation framework for adaptive HTML5 players and demonstrate its applicability by evaluating eight different players which are actually deployed in real-world services.}, address = {N.N.}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/1710.02459.pdf}, publisher = {N.N.}, url = {http://arxiv.org/abs/1710.02459} } @Article{Timmerer2017i, author = {Timmerer, Christian}, journal = {IEEE Communications Standards Magazine}, title = {Immersive Media Delivery: Overview of Ongoing Standardization Activities}, year = {2017}, issn = {2471-2825}, month = {dec}, number = {4}, pages = {71--74}, volume = {1}, abstract = {More and more immersive media applications and services are emerging on the market, but lack international standards to enable interoperability. This article provides an overview about ongoing standardization efforts in this exciting domain and highlights open research and standardization issues.}, address = {N.N.}, doi = {10.1109/MCOMSTD.2017.1700038}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/08258607.pdf}, publisher = {IEEE Communications Society} } @Article{Timmerer2017h, author = {Timmerer, Christian and Begen, Ali Cengiz}, journal = {Computing Now}, title = {Advancing Multimedia Content Distribution}, year = {2017}, month = {dec}, pages = {1}, address = {Los Alamitos, CA, USA}, language = {EN}, publisher = {IEEE Computer Society [online]}, url = {https://www.computer.org/web/computingnow/archive/advancing-multimedia-content-distribution-december-2017-introduction} } @Article{Timmerer2017g, author = {Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {MPEG Column: 116th MPEG Meeting}, year = {2017}, issn = {1947-4598}, month = {jul}, number = {4}, pages = {N.N.}, volume = {8}, address = {New York, NY, USA}, doi = {10.1145/3129151.3129152}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3129151.3129152} } @Article{Timmerer2017f, author = {Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {MPEG Column: 117th MPEG Meeting}, year = {2017}, issn = {1947-4598}, month = {jul}, number = {1}, pages = {N.N.}, volume = {9}, address = {New York, NY, USA}, doi = {10.1145/3129151.3129153}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3129151.3129153} } @Article{Timmerer2017e, author = {Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {MPEG Column: 118th MPEG Meeting}, year = {2017}, issn = {1947-4598}, month = {oct}, number = {4}, pages = {N.N.}, volume = {8}, address = {New York, NY, USA}, doi = {10.1145/3149647.3149656}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3149647.3149656} } @Article{Timmerer2017d, author = {Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {MPEG Column: 119th MPEG Meeting in Turin, Italy}, year = {2017}, issn = {1947-4598}, month = {dec}, number = {2}, pages = {N.N.}, volume = {9}, address = {New York, NY, USA}, doi = {10.1145/3173058.3173061}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3173058.3173061} } @Article{Timmerer2017c, author = {Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {Report from ACM MMSys 2017}, year = {2017}, issn = {1947-4598}, month = {dec}, number = {2}, pages = {N.N.}, volume = {9}, address = {New York, NY, USA}, doi = {10.1145/3173058.3173068}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3173058.3173068} } @Article{Timmerer2017a, author = {Timmerer, Christian and Begen, Ali Cengiz}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM)}, title = {Best Papers of the 2016 ACM Multimedia Systems (MMSys) Conference and Workshop on Network and Operating System Support for Digital Audio and Video (NOSSDAV) 2016}, year = {2017}, month = {jun}, number = {3s}, pages = {40:1--40:2}, volume = {13}, address = {New York, NY, USA}, doi = {10.1145/3084539}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/a40-timmerer.pdf}, publisher = {ACM Digital Library}, url = {http://doi.acm.org/10.1145/3084539} } @Article{Rainer2017a, author = {Rainer, Benjamin and Petscharnig, Stefan and Timmerer, Christian and Hellwagner, Hermann}, journal = {IEEE Transactions on Multimedia}, title = {Statistically Indifferent Quality Variation: An Approach for Reducing Multimedia Distribution Cost for Adaptive Video Streaming Services}, year = {2017}, month = {mar}, pages = {13}, volume = {19}, abstract = {Forecasts predict that Internet traffic will continue to grow in the near future. A huge share of this traffic is caused by multimedia streaming. The Quality of Experience (QoE) of such streaming services is an important aspect and in most cases the goal is to maximize the bit rate which -- in some cases -- conflicts with the requirements of both consumers and providers. For example, in mobile environments users may prefer a lower bit rate to come along with their data plan. Likewise, providers aim at minimizing bandwidth usage in order to reduce costs by transmitting less data to users while maintaining a high QoE. Today's adaptive video streaming services try to serve users with the highest bit rates which consequently results in high QoE. In practice, however, some of these high bit rate representations may not differ significantly in terms of perceived video quality compared to lower bit rate representations. In this paper, we present a novel approach to determine the statistically indifferent quality variation (SIQV) of adjacent video representations for adaptive video streaming services by adopting standard objective quality metrics and existing QoE models. In particular, whenever the quality variation between adjacent representations is imperceptible from a statistical point of view, the representation with higher bit rate can be substituted with a lower bit rate representation. As expected, this approach results in savings with respect to bandwidth consumption while still providing a high QoE for users. The approach is evaluated subjectively with a crowdsourcing study. Additionally, we highlight the benefits of our approach, by providing a case study that extrapolates possible savings for providers.}, address = {New York, USA}, doi = {10.1109/TMM.2016.2629761}, keywords = {Adaptive Video Streaming, Quality of Experience, MPEG-DASH}, language = {EN}, publisher = {IEEE}, url = {http://ieeexplore.ieee.org/document/7745907/} } @Article{Posch2017a, author = {Posch, Daniel and Rainer, Benjamin and Hellwagner, Hermann}, journal = {IEEE/ACM Transactions on Networking}, title = {SAF: Stochastic Adaptive Forwarding in Named Data Networking}, year = {2017}, month = {apr}, number = {2}, pages = {14}, volume = {25}, abstract = {Forwarding decisions in classical IP-based networks are predetermined by routing. This is necessary to avoid loops, inhibiting opportunities to implement an adaptive and intelligent forwarding plane. Consequently, content distribution efficiency is reduced due to a lack of inherent multi-path transmission. In Named Data Networking (NDN) instead, routing shall hold a supporting role to forwarding, providing sufficient potential to enhance content dissemination at the forwarding plane. In this paper we design, implement, and evaluate a novel probability-based forwarding strategy, called Stochastic Adaptive Forwarding (SAF) for NDN. SAF imitates a self-adjusting water pipe system, intelligently guiding and distributing Interests through network crossings circumventing link failures and bottlenecks. Just as real pipe systems, SAF employs overpressure valves enabling congested nodes to lower pressure autonomously. Through an implicit feedback mechanism it is ensured that the fraction of the traffic forwarded via congested nodes decreases. By conducting simulations we show that our approach outperforms existing forwarding strategies in terms of the Interest satisfaction ratio in the majority of the evaluated scenarios. This is achieved by extensive utilization of NDN's multipath and content-lookup capabilities without relying on the routing plane. SAF explores the local environment by redirecting requests that are likely to be dropped anyway. This enables SAF to identify new paths to the content origin or to cached replicas, circumventing link failures and resource shortages without relying on routing updates.}, address = {New York, USA}, doi = {10.1109/TNET.2016.2614710}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/saf.pdf}, publisher = {IEEE}, url = {https://dx.doi.org/10.1109/TNET.2016.2614710} } @Article{Posch2017, author = {Posch, Daniel and Rainer, Benjamin and Hellwagner, Hermann}, journal = {Computer Communication Review}, title = {Towards a Context-Aware Forwarding Plane in Named Data Networking supporting QoS}, year = {2017}, month = {jan}, number = {1}, pages = {9}, volume = {47}, abstract = {The emergence of Information-Centric Networking (ICN) provides considerable opportunities for context-aware data distribution in the network's forwarding plane. While packet forwarding in classical IP-based networks is basically predetermined by routing, ICN foresees an adaptive forwarding plane considering the requirements of network applications. As research in this area is still at an early stage, most of the work so far focused on providing the basic functionality, rather than on considering the available context information to improve Quality of Service (QoS). This article investigates to which extent existing forwarding strategies take account of the available context information and can therefore increase service quality. The article examines a typical scenario encompassing different user applications (Voice over IP, video streaming, and classical data transfer) with varying demands (context), and evaluates how well the applications' requirements are met by the existing strategies.}, address = {New York, USA}, doi = {10.1145/3041027.3041029}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/ccr.pdf}, publisher = {ACM SIGCOMM}, url = {https://dl.acm.org/citation.cfm?doid=3041027.3041029} } @Article{Pinheiro2017, author = {Pinheiro, Antonio and Timmerer, Christian}, journal = {SIGMultimedia Records}, title = {Standards Column: JPEG and MPEG}, year = {2017}, issn = {1947-4598}, month = {oct}, number = {1}, pages = {N.N.}, volume = {9}, address = {New York, NY, USA}, doi = {10.1145/3149647.3149648}, language = {EN}, publisher = {ACM}, url = {http://doi.acm.org/10.1145/3149647.3149648} } @Article{HHmartina2017, author = {Zhu, X and Mao, S and Hassan, M Hassan and Hellwagner, Hermann}, journal = {IEEE Transactions on Multimedia}, title = {Guest Editorial: Video Over Future Networks}, year = {2017}, issn = {1941-0077}, month = {oct}, number = {10}, pages = {2133 - 2135}, volume = {19}, abstract = {The papers in this special issue focus on the deployment of video over future networks. The past decade has seen how major improvements in broadband and mobile networks have led to widespread popularity of video streaming applications, and how the latter now becomes the major driving force behind exponentially growing Internet traffic. This special issue seeks to investigate these future Internet technologies through the prism of its most prevalent application, that of video communications. video.}, address = {Piscataway, NJ}, doi = {10.1109/TMM.2017.2743638}, keywords = {Special issues and sections, Streaming media, Mobile communication, Network architecture, Quality of experience, Ultra-high definition video}, language = {EN}, publisher = {IEEE}, url = {http://ieeexplore.ieee.org/document/8038904/} } @Article{timmerer2016_cn, author = {Timmerer, Christian}, journal = {Computing Now}, title = {The Future of Multimedia on the Internet}, year = {2016}, month = {nov}, pages = {1}, address = {Los Alamitos, CA, USA}, language = {EN}, publisher = {IEEE Computer Society [online]}, url = {https://www.computer.org/web/computingnow/archive/future-of-multimedia-on-the-internet-november-2016-introduction} } @Article{Westphal2016_jsac, author = {Westphal, Cedric and Melodia, Tommaso and Zhu, Wenww and Timmerer, Christian}, journal = {IEEE Journal on Selected Areas in Communications}, title = {Guest Editorial Video Distribution Over Future Internet}, year = {2016}, month = {aug}, number = {8}, pages = {2061-2062}, volume = {34}, address = {New York}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/JSAC2016_GE.pdf}, publisher = {IEEE Communications Society} } @Article{TimmererMR2016, author = {Timmerer, Christian and Maiero, Matteo and Rainer, Benjamin}, journal = {arXiv.org [cs.MM]}, title = {Which Adaptation Logic? An Objective and Subjective Performance Evaluation of HTTP-based Adaptive Media Streaming Systems}, year = {2016}, month = {jun}, pages = {11}, volume = {abs/1606.00341}, address = {N.N.}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/1606.00341.pdf}, publisher = {N.N.}, url = {http://arxiv.org/abs/1606.00341} } @Article{TimmererB2016, author = {Timmerer, Christian and Bertoni, Alan}, journal = {arXiv.org [cs.MM]}, title = {Advanced Transport Options for the Dynamic Adaptive Streaming over HTTP}, year = {2016}, month = {jun}, pages = {6}, volume = {abs/1606.00264}, address = {N.N.}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/1606.00264.pdf}, publisher = {N.N.}, url = {http://arxiv.org/abs/1606.00264} } @Article{Rainer2016a, author = {Rainer, Benjamin and Posch, Daniel and Leibetseder, Andreas and Theuermann, Sebastian and Hellwagner, Hermann}, journal = {Communications Magazine, IEEE}, title = {A Low-Cost NDN Testbed on Banana Pi Routers}, year = {2016}, month = sep, number = {9}, pages = {6}, volume = {54}, abstract = {The computer communication research community shows significant interest in the paradigm of Information-Centric Networking (ICN). Continuously, new proposals for ICN-related challenges (caching, forwarding, etc.) are published. However, due to a lack of a readily available testbed, the majority of these proposals is evaluated either by theoretical analysis and/or by conducting network simulations potentially masking further challenges that are not observable in synthetic environments. Therefore, this article presents a framework for an ICN testbed using low-budget physical hardware with little deployment and maintenance effort for the individual researcher; specifically, Named Data Networking is considered. The employed hardware and software are powerful enough for most research projects, but extremely resource intensive tasks may push both components towards their limits. The testbed framework is based on well established open source software and provides the tools to readily investigate important ICN characteristics on physical hardware emulating arbitrary network topologies. The article discusses the testbed architecture and provides first results obtained from emulations that investigate the performance of various forwarding strategies. The results indicate that further challenges have to be overcome when heading towards a real-world deployment of ICN-based communication.}, address = {New York, USA}, keywords = {ICN}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/commmagRainer.pdf}, publisher = {IEEE} } @Article{Rainer2016, author = {Rainer, Benjamin and Posch, Daniel and Hellwagner, Hermann}, journal = {Journal on Selected Areas in Communications}, title = {Investigating the Performance of Pull-based Dynamic Adaptive Streaming in NDN}, year = {2016}, issn = {1558-0008}, month = {aug}, number = {8}, pages = {11}, volume = {34}, abstract = {Adaptive content delivery is the state-of-the-art in real-time multimedia streaming. Leading streaming approaches, e.g., MPEG-DASH and Apple HLS, have been developed for classical IP-based networks, providing effective streaming by means of pure client-based control and adaptation. However, the research activities of the Future Internet community adopt a new course that is different from today's host-based communication model. So-called Information-Centric Networks are of considerable interest and are advertised as enablers for intelligent networks, where effective content delivery is to be provided as an inherent network feature. This paper investigates the performance gap between pure client-driven adaptation and the theoretical optimum in the promising Future Internet architecture Named Data Networking (NDN). The theoretical optimum is derived by modeling multimedia streaming in NDN as a fractional Multi-Commodity Flow Problem and by extending it taking caching into account. We investigate the multimedia streaming performance under different forwarding strategies, exposing the interplay of forwarding strategies and adaptation mechanisms. Furthermore, we examine the influence of network inherent caching on the streaming performance by varying the caching polices and the cache sizes.}, address = {New York, USA}, doi = {10.1109/JSAC.2016.2577365}, keywords = {Information-Centric Networking; Named Data Networking; Multimedia; Dynamic Adaptive Streaming.}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/jsac.pdf}, publisher = {IEEE} } @Article{timmerer2015_computer, author = {Timmerer, Christian and Ebrahimi, Touradj and Pereira, Fernando}, journal = {IEEE Computer}, title = {Toward a New Assessment of Quality}, year = {2015}, issn = {0018-9162}, month = {mar}, number = {3}, pages = {108-110}, volume = {48}, abstract = {A convergence of trends is shifting the focus of quality assessment from compliance with system design goals to fulfillment of user needs or expectations in different contexts.}, address = {Los Alamitos, CA, USA}, keywords = {Quality of Experience, Quality of Sensory Experience, Quality of Life}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/07063175.pdf}, publisher = {IEEE Computer Society} } @Article{Timmerer2015_ELetterNov, author = {Timmerer, Christian and Weinberger, Daniel and Smole, Martin and Grandl, Reinhard and Mueller, Christopher and Lederer, Stefan}, journal = {IEEE Multimedia Communications Technical Committee E-Letter}, title = {Cloud-based Transcoding and Adaptive Video Streaming-as-a-Service}, year = {2015}, month = {nov}, pages = {7--11}, address = {New York, NY, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/MMTC_bitcodin+bitdash.pdf}, publisher = {IEEE Communications Society [online]} } @Article{Timmerer2015_ELetter, author = {Timmerer, Christian and Maiero, Matteo and Rainer, Benjamin and Petscharnig, Stefan and Weinberger, Daniel and Mueller, Christopher and Lederer, Stefan}, journal = {IEEE Multimedia Communications Technical Committee E-Letter}, title = {Quality of Experience of Adaptive HTTP Streaming in Real-World Environments}, year = {2015}, month = {may}, pages = {6-9}, address = {New York, NY, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/QoE-DASH.pdf}, publisher = {IEEE Communications Society [online]}, talktype = {registered} } @Article{Rainer2015_MNA, author = {Rass, Stefan and Rainer, Benjamin and Vavti, Matthias and Göllner, Johannes and Peer, Andreas and Schauer, Stefan}, journal = {Mobile Networks and Applications}, title = {Secure Communication over Software-Defined Networks}, year = {2015}, month = {jan}, pages = {105--110}, address = {Springer US}, language = {EN}, publisher = {Springer}, talktype = {none} } @Article{Pohl2015b, author = {Pohl, Daniela and Bouchachia, Abdelhamid and Hellwagner, Hermann}, journal = {Neurocomputing}, title = {Online Indexing and Clustering of Social Media Data for Emergency Management}, year = {2015}, month = {jan}, pages = {168-179}, abstract = {Social media becomes a vital part in our daily communication practice, creating a huge amount of data and covering different real-world situations. Currently, there is a tendency in making use of social media during emergency management and response. Most of this effort is performed by a huge number of volunteers browsing through social media data and preparing maps that can be used by professional first responders. Automatic analysis approaches are needed to directly support the response teams in monitoring and also understanding the evolution of facts in social media during an emergency situation. In this paper, we investigate the problem of real-time sub-events identification in social media data (i.e., Twitter, Flickr and YouTube) during emergencies. A processing framework is presented serving to generate situational reports/summaries from social media data. This framework relies in particular on online indexing and online clustering of media data streams. Online indexing aims at tracking the relevant vocabulary to capture the evolution of sub-events over time. Online clustering, on the other hand, is used to detect and update the set of sub-events using the indices built during online indexing. To evaluate the framework, social media data related to Hurricane Sandy 2012 was collected and used in a series of experiments. In particular some online indexing methods have been tested against a proposed method to show their suitability. Moreover, the quality of online clustering has been studied using standard clustering indices. Overall the framework provides a great opportunity for supporting emergency responders as demonstrated in real-world emergency exercises.}, address = {Amsterdam, Netherlands}, doi = {10.1016/j.neucom.2015.01.084}, language = {EN}, publisher = {Elsevier} } @Article{timmerer2014_jsac, author = {Timmerer, Christian and Griwodz, Carsten and Begen, Ali Cengiz and Stockhammer, Thomas and Girod, Bernd}, journal = {IEEE Journal on Selected Areas in Communications}, title = {Guest Editorial: Adaptive Media Streaming}, year = {2014}, month = {apr}, number = {4}, pages = {681-683}, volume = {32}, address = {New York, NY, USA}, keywords = {Adaptive Media Streaming, DASH}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/06774588.pdf}, publisher = {IEEE Communications Society} } @Article{timmerer2014_computer, author = {Timmerer, Christian and Rainer, Benjamin}, journal = {IEEE Computer}, title = {The Social Multimedia Experience}, year = {2014}, issn = {0018-9162}, month = {mar}, number = {3}, pages = {67-69}, volume = {47}, abstract = {Inter-destination multimedia synchronization and quality of experience are critical to the success of social TV, which integrates television viewing with social networking.}, address = {Los Alamitos, CA, USA}, keywords = {Quality of Experience, Inter-Destination Media Synchronization, Social TV, DASH, IDMS, QoE}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/timmerer-sme-mar13.pdf}, publisher = {IEEE Computer Society} } @Article{Timmerer2014_MPEGColumnMar, author = {Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, title = {MPEG Column: 107th MPEG Meeting}, year = {2014}, issn = {1947-4598}, month = {mar}, number = {1}, pages = {1-2}, volume = {6}, address = {New York, NY, USA}, language = {EN}, publisher = {ACM}, url = {http://records.sigmm.ndlab.net/2014/02/mpeg-column-107th-mpeg-meeting/} } @Article{Timmerer2014_MMC, author = {Timmerer, Christian and Waltl, Markus and Rainer, Benjamin and Lederer, Stefan and Hellwagner, Hermann}, journal = {IEEE Multimedia Communications Technical Committee E-Letter}, title = {Enhancing 3D Video to enable a Fully Immersive Sensory Experiences}, year = {2014}, month = {jan}, number = {1}, pages = {23-26}, volume = {9}, address = {New York, NY, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/E-Letter-Jan2014.pdf}, publisher = {IEEE Communications Society [online]}, url = {http://committees.comsoc.org/mmc/e-news/E-Letter-Jan2014.pdf} } @Article{Rainer2014_AUTI, author = {Rainer, Benjamin and Timmerer, Christian}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM)}, title = {A Generic Utility Model Representing the Quality of Sensory Experience}, year = {2014}, month = {oct}, pages = {14:1--14:17}, address = {New York, NY, USA}, booktitle = {ACM Trans. Multimedia Comput. Commun. Appl.}, editor = {Steinmetz, Ralf and Ghinea, Gheorghita and Timmerer, Christian and Lin, Weisi and Gulliver, Stephen and Zha, Zheng-Jun and Zhang, Lei and M\"{u}hlh\"{a}user, Max and Smeaton, Alan}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/TOMCCAP-SE-Model.pdf}, publisher = {ACM}, talktype = {none} } @Article{Hossfeld2014_Computer, author = {Ho{\ss}feld, Tobias and Keimel, Christian and Timmerer, Christian}, journal = {Computer}, title = {Crowdsourcing Quality-of-Experience Assessments}, year = {2014}, month = {sep}, number = {9}, pages = {98--102}, volume = {47}, abstract = {Crowdsourced quality-of-experience (QoE) assessments are more cost-effective and flexible than traditional in-lab evaluations but require careful test design, innovative incentive mechanisms, and technical expertise to address various implementation challenges.}, address = {Los Alamitos, CA, USA}, doi = {10.1109/MC.2014.245}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/mco2014090098.pdf}, publisher = {IEEE Computer Society} } @Article{Ghinea2014_Tutorial, author = {Ghinea, Gheorghita and Timmerer, Christian and Lin, Weisi and Gulliver, Stephen}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM)}, title = {Mulsemedia: State of the Art, Perspectives, and Challenges}, year = {2014}, issn = {1551-6857}, month = {sep}, number = {1s}, pages = {17:1--17:23}, volume = {11}, abstract = {Mulsemedia—multiple sensorial media—captures a wide variety of research efforts and applications. This article presents a historic perspective on mulsemedia work and reviews current developments in the area. These take place across the traditional multimedia spectrum—from virtual reality applications to computer games—as well as efforts in the arts, gastronomy, and therapy, to mention a few. We also describe standardization efforts, via the MPEG-V standard, and identify future developments and exciting challenges the community needs to overcome.}, address = {New York, NY, USA}, keywords = {Mulsemedia, contour perception, flow visualization, multisensory, perceptual theory, visual cortex, visualization}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/a17-ghinea.pdf}, publisher = {ACM} } @Article{Ghinea2014_Intro, author = {Ghinea, Gheorghita and Timmerer, Christian and Lin, Weisi and Gulliver, Stephen}, journal = {ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM)}, title = {Guest Editorial: Special Issue on Multiple Sensorial (MulSeMedia) Multimodal Media: Advances and Applications}, year = {2014}, issn = {1551-6857}, month = {sep}, number = {1s}, pages = {9:1--9:2}, volume = {11}, address = {New York, NY, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/a9-ghinea.pdf}, publisher = {ACM} } @Article{Waltl2012_MPEGVSI, author = {Waltl, Markus and Rainer, Benjamin and Timmerer, Christian and Hellwagner, Hermann}, journal = {Signal Processing: Image Communication}, title = {An End-to-End tool chain for sensory experience based on MPEG-V}, year = {2013}, month = {feb}, number = {2}, pages = {136--150}, volume = {28}, abstract = {This paper provides an overview of our research conducted in the area of Sensory Experience including our implementations using MPEG-V Part 3 entitled ”Sensory Information”. MPEG-V Part 3 introduces Sensory Experience as a tool to increase the Quality of Experience by annotating traditional multimedia data with sensory effects. These sensory effects are rendered on special devices like fans, vibration chairs, ambient lights, scent disposers, water sprayers, or heating/cooling devices stimulating senses beyond the traditional ones. The paper's main focus is on the end-to-end aspects including the generation, transmission, and synchronized rendering of sensory effects with the traditional multimedia data taking movie clips as an example. Therefore, we present in this paper an open source tool chain that provides a complete end-to-end sensory effect generation and consumption framework. Furthermore, we summarize results from various subjective quality assessments conducted in this area. Finally, we point out research challenges that may encourage further research within this emerging domain.}, address = {Amsterdam, Netherlands}, doi = {10.1016/j.image.2012.10.009}, keywords = {Quality of Experience; Sensory Experience; Subjective Quality Assessment; Experimental Results; MPEG-V; Annotation Tool; Simulation Tool; Web Browser Plug-in; Sensory Information}, language = {EN}, publisher = {Elsevier}, url = {http://dx.doi.org/10.1016/j.image.2012.10.009} } @Article{Timmerer2013_MPEGColumnSep, author = {Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, title = {MPEG Column: 105th MPEG Meeting}, year = {2013}, issn = {1947-4598}, month = {sep}, number = {3}, pages = {1-2}, volume = {5}, address = {New York, NY, USA}, language = {EN}, publisher = {ACM}, url = {http://records.sigmm.ndlab.net/2013/08/mpeg-column-105th-mpeg-meeting/} } @Article{Timmerer2013_MPEGColumnMar, author = {Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, title = {MPEG column: 103rd MPEG meeting}, year = {2013}, issn = {1947-4598}, month = {mar}, number = {1}, pages = {1-3}, volume = {5}, address = {New York, NY, USA}, language = {EN}, publisher = {ACM}, url = {http://records.sigmm.ndlab.net/2013/01/mpeg-column-103rd-mpeg-meeting/} } @Article{Timmerer2013_MPEGColumnDec, author = {Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, title = {MPEG Column: 106th MPEG Meeting}, year = {2013}, issn = {1947-4598}, month = {dec}, number = {4}, pages = {1-2}, volume = {5}, address = {New York, NY, USA}, language = {EN}, publisher = {ACM}, url = {http://records.sigmm.ndlab.net/2014/01/mpeg-column-106th-mpeg-meeting/} } @Article{Timmerer2013_CN, author = {Timmerer, Christian and Vetro, Anthony}, journal = {Computing Now}, title = {Recent MPEG Standards for Future Media Ecosystems}, year = {2013}, month = {oct}, number = {10}, pages = {1}, volume = {6}, address = {Los Alamitos, CA, USA}, language = {EN}, publisher = {IEEE Computer Society [online]}, url = {http://www.computer.org/portal/web/computingnow/archive/october2013} } @Article{Pohl2013d, author = {Pohl, Daniela and Bouchachia, Abdelhamid and Hellwagner, Hermann}, journal = {Multimedia Tools and Applications}, title = {Social Media for Crisis Management: Clustering Approaches for Sub-Event Detection}, year = {2013}, month = {dec}, pages = {1-32}, address = {Springer, NY, US}, language = {EN}, publisher = {Springer US} } @Article{Mueller2013_MMC, author = {Mueller, Christopher and Lederer, Stefan and Timmerer, Christian}, journal = {IEEE Multimedia Communications Technical Committee E-Letter}, title = {Fair Share Dynamic Adaptive Streaming over HTTP}, year = {2013}, month = {mar}, number = {2}, pages = {30-33}, volume = {8}, abstract = {Multimedia delivery over the Hypertext Transfer Protocol (HTTP) is currently very popular and with MPEGs' Dynamic Adaptive Streaming over HTTP (DASH) a standard is available to provide interoperability and enable large-scale deployments using existing infrastructures (servers, proxies, caches, etc.). This paper identifies some issue when multiple DASH clients compete for a bandwidth bottleneck when transparent proxy caches are deployed. Therefore, we propose a fair share adaptation scheme to be included within the client which – through experimental results – achieve a more efficient utilization of the bottleneck bandwidth and less quality switches.}, address = {New York, NY, USA}, keywords = {Dynamic Adaptive Streaming over HTTP, DASH, Fair Adaptation, Proxy Cache, Multimedia}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/E-Letter-March13.pdf}, publisher = {IEEE Communications Society [online]}, url = {http://committees.comsoc.org/mmc/e-news/E-Letter-March13.pdf} } @Article{Lederer2013_MMC, author = {Lederer, Stefan and Mueller, Christopher and Grandl, Reinhard and Timmerer, Christian}, journal = {IEEE Multimedia Communications Technical Committee E-Letter}, title = {Adaptive Multimedia Streaming over Information-Centric Networks in Mobile Networks using Multiple Mobile Links}, year = {2013}, month = {nov}, number = {6}, pages = {38-41}, volume = {8}, address = {New York, NY, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/E-Letter-Nov2013.pdf}, publisher = {IEEE Communications Society [online]}, url = {http://committees.comsoc.org/mmc/e-news/E-Letter-Nov2013.pdf} } @Article{Kud2013_SPIC, author = {Kudumakis, Panos and Sandler, Mark and Anadiotis, Angelos-Christos G and Venieris, Iakovos S and Difino, Angelo and Wang, Xin and Tropea, Giuseppe and Grafl, Michael and Rodríguez-Doncel, Víctor and Llorente, Silvia and Delgado, Jaime}, journal = {Signal Processing: Image Communication}, title = {MPEG-M: A Digital Media Ecosystem for Interoperable Applications}, year = {2013}, issn = {09235965}, month = {dec}, pages = {24}, abstract = {MPEG-M is a suite of ISO/IEC standards (ISO/IEC 23006) that has been developed under the auspices of Moving Picture Experts Group (MPEG). MPEG-M, also known as Multimedia Service Platform Technologies (MSPT), facilitates a collection of multimedia middleware APIs and elementary services as well as service aggregation so that service providers can offer users a plethora of innovative services by extending current IPTV technology toward the seamless integration of personal content creation and distribution, e-commerce, social networks and Internet distribution of digital media.}, address = {Amsterdam, Netherlands}, doi = {10.1016/j.image.2013.10.006}, language = {EN}, publisher = {Elsevier}, url = {http://dx.doi.org/10.1016/j.image.2013.10.006} } @Article{Grafl2013_ComCom, author = {Grafl, Michael and Timmerer, Christian and Hellwagner, Hermann and Cherif, Wael and Ksentini, Adlen}, journal = {Computer Communications}, title = {Hybrid Scalable Video Coding for {HTTP}-based Adaptive Media Streaming with High-Definition Content}, year = {2013}, issn = {01403664}, month = {dec}, pages = {11}, 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.}, address = {Amsterdam, Netherlands}, language = {EN}, publisher = {Elsevier} } @Article{Grafl2012_MM, author = {Grafl, Michael and Timmerer, Christian and Hellwagner, Hermann and Xilouris, George and Gardikis, Georgios and Renzi, Daniele and Battista, Stefano and Borcoci, Eugen and Negru, Daniel}, journal = {IEEE MultiMedia}, title = {Scalable Media Coding enabling Content-Aware Networking}, year = {2013}, issn = {1070-986X}, month = {apr}, number = {2}, pages = {30-41}, volume = {20}, 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.}, address = {Los Alamitos, CA, USA}, doi = {http://doi.ieeecomputersociety.org/10.1109/MMUL.2012.57}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/SMC_enabling_CAN.pdf}, publisher = {IEEE Computer Society} } @Article{Waltl2012_MTAP, author = {Waltl, Markus and Timmerer, Christian and Rainer, Benjamin and Hellwagner, Hermann}, journal = {Multimedia Tools and Applications}, title = {Sensory Effects for Ambient Experiences in the World Wide Web}, year = {2012}, month = {may}, number = {-}, pages = {1--20}, volume = {-}, abstract = {More and more content in various formats becomes available via the WorldWideWeb (WWW). Currently availableWeb browsers are able to access and interpret these contents (i.e., Web videos, text, image, and audio). These contents stimulate only senses like audition or vision. Recently, it has been proposed to stimulate also other senses while consuming multimedia content, through so-called sensory effects. These sensory effects aim to enhance the ambient experience by providing effects such as light, wind, vibration, etc. The effects are represented as Sensory Effect Metadata (SEM) description which is associated to multimedia content and is rendered on devices like fans, vibration chairs, or lamps. In this paper we present two subjective quality assessments which comprise sensory effects, such as light, in the area of the WWW and their results achieved. The first assessment evaluates the influence of light effects on the Quality of Experience (QoE). The second assessment measures the impact of different settings for the color calculation on the viewing experience. Furthermore, we describe a Web browser plug-in for Mozilla Firefox which is able to render such sensory effects that are provided via the WWW.}, address = {Berlin, Heidelberg, New York}, doi = {10.1007/s11042-012-1099-8}, keywords = {World Wide Web, MPEG-V, Subjective quality assessment, Sensory effects, Quality of multimedia experience}, language = {EN}, publisher = {Springer Verlag}, url = {http://dx.doi.org/10.1007/s11042-012-1099-8} } @Article{Timmerer2012_MPEGColumnSep, author = {Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, title = {MPEG column: 101st MPEG meeting}, year = {2012}, issn = {1947-4598}, month = {sep}, number = {3}, pages = {9-11}, volume = {4}, address = {New York, NY, USA}, language = {EN}, publisher = {ACM}, url = {http://records.sigmm.ndlab.net/2012/11/mpeg-column-101st-mpeg-meeting/} } @Article{Timmerer2012_MPEGColumnJun, author = {Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, title = {MPEG column: 100th MPEG meeting}, year = {2012}, issn = {1947-4598}, month = {jun}, number = {2}, pages = {2-3}, volume = {4}, address = {New York, NY, USA}, language = {EN}, publisher = {ACM}, url = {http://records.sigmm.ndlab.net/2012/06/mpeg-column-100th-mpeg-meeting/} } @Article{Timmerer2012_MPEGColumnDec, author = {Timmerer, Christian}, journal = {ACM SIGMultimedia Records}, title = {MPEG column: 102nd MPEG meeting}, year = {2012}, issn = {1947-4598}, month = {dec}, number = {4}, pages = {1-2}, volume = {4}, address = {New York, NY, CUSA}, language = {EN}, publisher = {ACM}, url = {http://records.sigmm.ndlab.net/2012/12/mpeg-column-102nd-mpeg-meeting/} } @Article{Timmerer2012909, author = {Timmerer, Christian and Waltl, Markus and Rainer, Benjamin and Hellwagner, Hermann}, journal = {Signal Processing: Image Communication}, title = {Assessing the quality of sensory experience for multimedia presentations}, year = {2012}, month = {sep}, number = {8}, pages = {909--916}, volume = {27}, abstract = {This paper introduces the concept of sensory experience by utilizing sensory effects such as wind or lighting as another dimension which contributes to the quality of the user experience. In particular, we utilize a representation format for sensory effects that are attached to traditional multimedia resources such as audio, video, and image contents. Sensory effects (e.g., wind, lighting, explosion, heat, cold) are rendered on special devices (e.g., fans, ambient lights, motion chair, air condition) in synchronization with the traditional multimedia resources and shall stimulate other senses than audition and vision (e.g., mechanoreception, equilibrioception, thermoreception), with the intention to increase the users Quality of Experience (QoE). In particular, the paper provides a comprehensive introduction into the concept of sensory experience, its assessment in terms of the QoE, and related standardization and implementation efforts. Finally, we will highlight open issues and research challenges including future work.}, address = {Amsterdam, Netherlands}, doi = {10.1016/j.image.2012.01.016}, keywords = {Quality of Experience, Sensory experience, Subjective quality assessment, Experimental results, MPEG-V}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/1-s2.0-S0923596512000252-main.pdf}, publisher = {Elsevier}, url = {http://dx.doi.org/10.1016/j.image.2012.01.016} } @Article{Milojicic2012, author = {Milojicic, Dejan and Arlitt, Martin and Seligmann, Doree Duncan and Thiruvathukal, George and Timmerer, Christian}, journal = {Computer}, title = {Innovation Mashups: Academic Rigor Meets Social Networking Buzz}, year = {2012}, issn = {0018-9162}, month = {sep}, number = {9}, pages = {101-105}, volume = {45}, abstract = {Exploring new options for publishing and content delivery offers an enormous opportunity to improve the state of the art and further modernize academic and professional publications.}, address = {Los Alamitos, CA, USA}, doi = {http://doi.ieeecomputersociety.org/10.1109/MC.2012.313}, keywords = {STCs, IEEE Computer Society, mashups, Computing Now}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/mco2012090101.pdf}, publisher = {IEEE Computer Society} } @Article{Hossfeld2012, author = {Ho{\ss}feld, Tobias and Schatz, Raimund and Varela, Martin and Timmerer, Christian}, journal = {Communications Magazine, IEEE}, title = {Challenges of QoE Management for Cloud Applications}, year = {2012}, month = {apr}, number = {4}, pages = {28-36}, volume = {50}, abstract = {Cloud computing is currently gaining enormous momentum due to a number of promised benefits: ease of use in terms of deployment, administration, and maintenance, along with high scalability and flexibility to create new services. However, as more personal and business applications migrate to the cloud, service quality will become an important differentiator between providers. In particular, quality of experience as perceived by users has the potential to become the guiding paradigm for managing quality in the cloud. In this article, we discuss technical challenges emerging from shifting services to the cloud, as well as how this shift impacts QoE and QoE management. Thereby, a particular focus is on multimedia cloud applications. Together with a novel QoE-based classification scheme of cloud applications, these challenges drive the research agenda on QoE management for cloud applications.}, address = {New York, NY, USA}, doi = {10.1109/MCOM.2012.6178831}, keywords = {cloud computing, multimedia computing, software quality, QoE management, QoE-based classification scheme, multimedia cloud applications, quality management, quality of experience, service quality, Cloud computing, Multimedia communication, Quality of service, Streaming media}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/06178831.pdf}, publisher = {IEEE Communications Society} } @Article{Hellwagner2011a, author = {Hellwagner, Hermann and Hofbauer, Heinz and Kuschnig, Robert and Stütz, Thomas and Uhl, Andreas}, journal = {Journal on Signal Processing: Image Communication}, title = {Secure transport and adaptation of MC-EZBC video utilizing H.264-based transport protocols}, year = {2011}, issn = {0923-5965}, month = {nov}, pages = {30}, abstract = {Universal Multimedia Access (UMA) calls for solutions where content is created once and subsequently adapted to given requirements. With regard to UMA and scalability, which is required often due to a wide variety of end clients, the best suited codecs are wavelet based (like the MC-EZBC) due to their inherent high number of scaling options. However, most transport technologies for delivering videos to end clients are targeted toward the H.264/AVC standard or, if scalability is required, the H.264/SVC. In this paper we will introduce a mapping of the MC-EZBC bitstream to existing H.264/SVC based streaming and scaling protocols. This enables the use of highly scalable wavelet based codecs on the one hand and the utilization of already existing network technologies without accruing high implementation costs on the other hand. Furthermore, we will evaluate different scaling options in order to choose the best option for given requirements. Additionally, we will evaluate different encryption options based on transport and bitstream encryption for use cases where digital rights management is required.}, address = {Amsterdam, Netherlands}, doi = {10.1016/j.image.2011.11.002}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Elsevier_SPIC_Hellwagner11a.pdf}, publisher = {Elsevier B.V.} } @Article{Eberhard2011a, author = {Eberhard, Michael and Kumar, Amit and Mignanti, Silvano and Petrocco, Riccardo and Uitto, Mikko}, journal = {International Journal on Advances in Internet Technology}, title = {A Framework for Distributing Scalable Content over Peer-to-Peer Networks}, year = {2011}, month = {sep}, number = {1\&2}, pages = {1-13}, volume = {4}, abstract = {Peer-to-Peer systems are nowadays a very popular solution for multimedia distribution, as they provide significant cost benefits compared with traditional server-client distribution. Additionally, the distribution of scalable content enables the consumption of the content in a quality suited for the available bandwidth and the capabilities of the end-user devices. Thus, the distribution of scalable content over Peer-to-Peer network is a very actual research topic. This paper presents a framework for the distribution of scalable content in a fully distributed Peer-to-Peer network. The architectural description includes how the scalable layers of the content are mapped to the pieces distributed in the Peer-to-Peer system and detailed descriptions of the producer- and consumer-site architecture of the system. Additionally, an evaluation of the system’s performance in different scenarios is provided. The test series in the evaluation section assess the performance of our layered piece-picking core and provide a comparison of the performance of our system’s multi layer and single layer implementations. The presented system is to our knowledge the first open-source Peer-to-Peer network with full Scalable Video Coding support.}, address = {N/A}, keywords = {Peer-to-Peer; Scalable Video Coding; Packetizing; Error Concealment; Performance Evaluation}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/svc_framework_iaria.pdf}, publisher = {IARIA} } @Article{Timmerer2010_MXM_IEEEMM, author = {Timmerer, Christian and Chiariglione, Filippo and Preda, Marius and Doncel, Victor Rodriguez}, journal = {IEEE Multimedia}, title = {Accelerating Media Business Developments with the MPEG Extensible Middleware}, year = {2010}, issn = {1070-986X}, month = {sep}, number = {3}, pages = {74--78}, volume = {17}, abstract = {Editor’s Note: Media applications are becoming increasingly complex. They handle many data formats, run across multiple platforms, and support a wide range of functions. This article describes a standardized set of protocols and APIs that provides efficient access to individual system components, enables rapid deployment of new applications, and improves portability. —Anthony Vetro}, address = {Los Alamitos, CA, USA}, doi = {10.1109/MMUL.2010.52}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/mmu2010030074.pdf}, publisher = {IEEE}, url = {http://doi.ieeecomputersociety.org/10.1109/MMUL.2010.52} } @Article{Timmerer2010_DeliveryContextDescriptionFormats, author = {Timmerer, Christian and Jaborning, Johannes and Hellwagner, Hermann}, journal = {Journal of Digital Information Management}, title = {A Survey on Delivery Context Description Formats - A Comparison and Mapping Model}, year = {2010}, month = {feb}, number = {1}, pages = {16-27}, volume = {8}, abstract = {Nowadays, mobile devices have implemented several transmission technologies which enable access to the Internet and increase the bit rate for data exchange. Despite modern mobile processors and high-resolution displays, mobile devices will never reach the stage of a powerful notebook or desktop system (for example, due to the fact of battery powered CPUs or just concerning the small-sized displays). Due to these limitations, the deliverable content for these devices should be adapted based on their capabilities including a variety of aspects (e.g., from terminal to network characteristics). These capabilities should be described in an interoperable way. In practice, however, there are many standards available and a common mapping model between these standards is not in place. Therefore, in this paper we describe such a mapping model and its implementation aspects. In particular, we focus on the whole delivery context (i.e., terminal capabilities, net- work characteristics, user preferences, etc.) and investigated the two most prominent state-of-the-art description schemes, namely User Agent Profile (UAProf) and Usage Environment Description (UED).}, address = {Chennai, India}, keywords = {CC/PP, DCO, Delivery Context, Metadata, UAProf, UED}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/A Survey on Delivery Context Description Formats – A Comparison and Mapping Model.pdf}, publisher = {Digital Information Research Foundation} } @Article{Szkaliczki2010, author = {Szkaliczki, Tibor and Eberhard, Michael and Hellwagner, Hermann and Szobonya, László}, journal = {Electronic Notes in Discrete Mathematics}, title = {Piece Selection Algorithm for Layered Video Streaming in P2P Networks}, year = {2010}, issn = {1571-0653}, month = {aug}, note = {ISCO 2010 - International Symposium on Combinatorial Optimization}, pages = {1265-1272}, volume = {36}, abstract = {This paper introduces the piece selection problem that arises when streaming layered video content over peer-to-peer networks. The piece selection algorithm decides periodically which pieces to request from other peers (network nodes) for download. The main goal of the piece selection algorithm is to provide the best possible quality for the available bandwidth. Our recommended solution approaches are related to the typical problems and solutions in the knapsack problem.}, address = {New York, USA}, doi = {10.1016/j.endm.2010.05.160}, keywords = {streaming, layered video, knapsack problem}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/ISCO'10_Eberhard.pdf}, publisher = {Elsevier Inc.}, url = {http://www.sciencedirect.com/science/article/B75GV-50JJF7F-5P/2/7d978923400f50d4c42165003c64c351} } @Article{Lopez2010, author = {Lopez, Fernando and Jannach, Dietmar and Martínez, Jose Maria and Timmerer, Christian and García, Narciso and Hellwagner, Hermann}, journal = {Journal of Applied Intelligence}, title = {Bounded non-deterministic planning for multimedia adaptation}, year = {2010}, month = {jul}, pages = {32}, abstract = {This paper proposes a novel combination of arti- ficial intelligence planning and other techniques for improv- ing decision-making in the context of multi-step multime- dia content adaptation. In particular, it describes a method that allows decision-making (selecting the adaptation to perform) in situations where third-party pluggable multi- media conversion modules are involved and the multime- dia adaptation planner does not know their exact adapta- tion capabilities. In this approach, the multimedia adapta- tion planner module is only responsible for a part of the required decisions; the pluggable modules make additional decisions based on different criteria. We demonstrate that partial decision-making is not only attainable, but also in- troduces advantages with respect to a system in which these conversion modules are not capable of providing additional decisions. This means that transferring decisions from the multi-step multimedia adaptation planner to the pluggable conversion modules increases the flexibility of the adapta- tion. Moreover, by allowing conversion modules to be only partially described, the range of problems that these modules can address increases, while significantly decreasing both the description length of the adaptation capabilities and the planning decision time. Finally, we specify the conditions under which knowing the partial adaptation capabilities of a set of conversion modules will be enough to compute a proper adaptation plan.}, address = {Springer New York}, doi = {10.1007/s10489-010-0242-3}, keywords = {Bounded non-deterministic multimedia adaptation, Planning, Decision-making, MPEG-7, MPEG-21}, language = {EN}, publisher = {Springer}, url = {http://www.springerlink.com/content/751g123vp1574qt5/} } @Article{Kosch2009, author = {Kosch, Harald and Timmerer, Christian}, journal = {IEEE Computing Now}, title = {Multimedia Metadata and Semantic Management}, year = {2009}, month = dec, number = {December 2009}, pages = {00}, volume = {Multimedia Metadata and Semantic Management}, address = {Los Alamitos, CA, USA}, language = {EN}, publisher = {IEEE} } @Article{Hellwagner2009, author = {Hellwagner, Hermann and Kuschnig, Robert and Stütz, Thomas and Uhl, Andreas}, journal = {Journal on Signal Processing: Image Communication}, title = {Efficient In-Network Adaptation of Encrypted {H.264/SVC} Content}, year = {2009}, month = {jul}, number = {9}, pages = {740-758}, volume = {24}, 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.}, address = {Amsterdam}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Elsevier_SPIC_Hellwagner09a.pdf}, publisher = {Elsevier B.V.} } @Article{Eberhard2009a, author = {Eberhard, Michael and Timmerer, Christian and Quacchio, Emanuele and Hellwagner, Hermann}, journal = {IEEE Wireless Communications}, title = {An Interoperable Delivery Framework for Scalable Media Resources}, year = {2009}, month = {oct}, number = {Vol. 16, No. 5}, pages = {58-63}, volume = {Oktober 2009}, 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.}, address = {Los Alamitos, CA, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/ieeewireless_eberhard.pdf}, publisher = {IEEE} } @Article{Tusch2008, author = {Tusch, Roland and Jakab, Michael and Köpke, Julius and Krätschmer, Armin and Kropfberger, Michael and Kuchler, Sigrid and Ofner, Michael and Hellwagner, Hermann and Böszörmenyi, Laszlo}, journal = {International Journal of Digital Multimedia Broadcasting}, title = {Context-Aware UPnP-AV Services for Adaptive Home Multimedia Systems}, year = {2008}, month = sep, pages = {12}, volume = {Vol. 2008}, 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.}, address = {Cairo}, doi = {doi:10.1155/2008/835438}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Context-Aware UPnP-AV Services for Adaptive Home Multimedia Systems.pdf}, publisher = {Hindawi Publishing Corporation}, url = {http://www.hindawi.com/journals/ijdmb/volume-2008/} } @Article{Timmerer2008g, author = {Timmerer, Christian and Hellwagner, Hermann}, journal = {Informatik Spektrum}, title = {Das MPEG-21 Multimedia Framework}, year = {2008}, month = dec, number = {6}, pages = {576-579}, volume = {31}, address = {Berlin, Heidelberg, New York}, language = {DE}, publisher = {Springer} } @Article{Sidibe2008, author = {Sidibe, Mamadou and Koumaras, Harilaos and Kofler, Ingo and Mehaoua, Ahmed and Kourtis, Anastasios and Timmerer, Christian}, journal = {Journal on Signal, Image and Video Processing}, title = {A novel monitoring architecture for media services adaptation based on network QoS to perceived QoS mapping}, year = {2008}, month = dec, number = {4}, pages = {307-320}, volume = {2}, 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.}, address = {London, United Kingdom}, doi = {10.1007/s11760-008-0083-2}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/SIVP08_MonitoringArchitecture_Preprint.pdf}, publisher = {Springer} } @Article{Reiterer2008, author = {Reiterer, Bernhard and Concolato, Cyril and Lachner, Janine and Le Feuvre, Jean and Moissinac, Jean-Claude and Lenzi, Stefano and Chessa, Stefano and Ferrá, Enrique Fernández and Menaya, Juan José González and Hellwagner, Hermann}, journal = {The Visual Computer, International Journal of Computer Graphics}, title = {User-centric universal multimedia access in home networks}, year = {2008}, issn = {01782789}, month = jul, number = {7-9}, pages = {837-845}, volume = {24}, 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.}, address = {Berlin, Heidelberg, New York}, doi = {10.1007/s00371-008-0265-5}, keywords = {Universal Multimedia Access · Multimedia adaptation · UPnP AV · Context awareness · Content sharing}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/User-centric universal multimedia access in home networks.pdf}, publisher = {Springer}, url = {http://http://www.springerlink.com/content/fpjj19237704788k/} } @Article{Mylonas2008, author = {Mylonas, Phivos and Hellwagner, Hermann and Castells, Pablo and Wallace, Manolis}, journal = {Signal, Image and Video Processing}, title = {Signal, image and video processing (SIVP) special issue on “multimedia semantics, adaptation and personalization” Editorial}, year = {2008}, issn = {1863-1711}, month = oct, number = {4}, pages = {287-288}, volume = {2/2008}, address = {Berlin, Heidelberg, New York}, language = {EN}, publisher = {Springer}, url = {http://www.springerlink.com/content/f672w10742502436/?p=d30247019a4d4df6a6c1ea2a5da5e38d&pi=0} } @Article{Kuschnig2008, author = {Kuschnig, Robert and Kofler, Ingo and Ransburg, Michael and Hellwagner, Hermann}, journal = {Journal of Visual Communication and Image Representation}, title = {Design options and comparison of in-network H.264/SVC adaptation}, year = {2008}, month = dec, number = {8}, pages = {529-542}, volume = {19}, 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.}, address = {Amsterdam}, doi = {10.1016/j.jvcir.2008.07.004}, keywords = {Scalable video coding (H.264/SVC), In-network adaptation, RTP/RTSP MANE, MPEG-21 Digital Item Adaptation (DIA), Generic Bitstream Syntax Description (gBSD)}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/JVCIR08_In-network_H.264-AVC_Adaptation.pdf}, publisher = {Elsevier B.V.} } @Article{Kofler2008a, author = {Kofler, Ingo and Seidl, Joachim and Timmerer, Christian and Hellwagner, Hermann and Ahmed, Toufik}, journal = {Journal on Signal, Image and Video Processing}, title = {Using MPEG-21 for Cross-layer Multimedia Content Adaptation}, year = {2008}, month = dec, number = {4}, pages = {355-370}, volume = {2}, abstract = {This paper presents a cross-layer model—formulated using interoperable description formats—for the adaptation of scalable H.264/MPEG-4 AVC (i.e., SVC) content in a video streaming system operating on aWireless LANaccess network without QoS mechanisms.SVCcontent adaptation on the server takes place on the application layer using an adaptation process compliant with the MPEG-21 Digital Item Adaptation (DIA) standard, based on input comprised of MPEG-21 DIA descriptions of content and usage environment parameters. The latter descriptions integrate information from different layers, e.g., device characteristics and packet loss rate, in an attempt to increase the interoperability of this cross-layer model, thus making it applicable to other models. For the sake of deriving model parameters, performance measurements from two wireless access point models were taken in account. Throughout the investigation it emerged that the behavior of the system strongly depends on the access point. Therefore, we investigated the use of end-to-end-based rate control algorithms for steering the content adaptation. Simulations of rate adaptation algorithms were subsequently performed, leading to the conclusion that a TFRC-based adaptation technique (TCP-Friendly Rate Control) performs quite well in adapting to limited bandwidth and varying network conditions. In the paper we demonstrate howTFRC-based content adaptation can be realized using MPEG-21 tools.}, address = {London, United Kingdom}, doi = {10.1007/s11760-008-0088-x}, keywords = {Multimedia content adaptation · Cross-layer design · MPEG-21 Digital Item Adaptation · Rate control}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/SIVP08_CrossLayer_Preprint.pdf}, publisher = {Springer} } @Article{Prangl2007a, author = {Prangl, Martin and Szkaliczki, Tibor and Hellwagner, Hermann}, journal = {IEEE Transactions on Circuits and Systems for Video Technology}, title = {A Framework for Utility-Based Multimedia Adaptation}, year = {2007}, issn = {1051-8215}, month = jun, number = {6}, pages = {719-728}, volume = {17/2007}, abstract = {Content adaptation is an important issue of multimedia frameworks in order to achieve universal multimedia access (UMA), i.e., to enable consumption of multimedia content independently of the given resource limitations, terminal capabilities, and user preferences. The digital item adaptation (DIA) standard, one of the core specifications of the MPEG-21 framework, supports content adaptation considering a wide range of networks, devices, and user preferences. Most adaptive multimedia frameworks targeting the UMA vision do not consider utility aspects in their adaptation decisions. This paper focuses on a generic semantic-based audio–visual utility model for DIA that aims to enhance the multimedia experience for the user. Our proposed model is able to take the semantics and the perceptual features of the content as well as the users' specific utility aspects into account. Based on a detailed analysis of these constraints, we will show how the model reacts on individual input data. For choosing the best adaptation decision considering resource limitations on client and server sides as well as network characteristics, we evaluate four algorithms for performing this adaptation decision taking task. We will discuss results according to some use case scenarios.}, address = {Los Alamitos, CA, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/A Framework for Utility-Based Multimedia Adaptation.pdf}, publisher = {IEEE} } @Article{Boeszoermenyi2007a, author = {Böszörmenyi, Laszlo and Hellwagner, Hermann and Schojer, Peter}, journal = {Multimedia Systems}, title = {Metadata-driven optimal transcoding in a multimedia proxy}, year = {2007}, month = jul, number = {Issue 1}, pages = {51-68}, volume = {Vol. 13}, abstract = {An adaptive multimedia proxy is presented which provides (1) caching, (2) filtering, and (3) media gateway functionalities. The proxy can perform media adaptation on its own, either relying on layered coding or using transcoding mainly in the decompressed domain. A cost model is presented which incorporates user requirements, terminal capabilities, and video variations in one formula. Based on this model, the proxy acts as a general broker of different user requirements and of different video variations. This is a first step towards What You Need is What YouGet (WYNIWYG) video services, which deliver videos to users in exactly the quality they need and are willing to pay for. The MPEG-7 and MPEG-21 standards enable this in an interoperable way. A detailed evaluation based on a series of simulation runs is provided.}, address = {Berlin, Heidelberg, New York}, doi = {9780769530406}, keywords = {Video proxy · Video caching · Media gateway · Media adaptation · Metadata · MPEG-7 · MPEG-21 · Cache replacement}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Metadata-driven optimal transcoding in a multimedia proxy.pdf}, publisher = {Springer} } @Article{Jannach2006, author = {Jannach, Dietmar and Leopold, Klaus and Timmerer, Christian and Hellwagner, Hermann}, journal = {Applied Intelligence - Special Issue: Innovations in Applied Artificial Intelligence}, title = {A Knowledge-Based Framework For Multimedia Adaptation}, year = {2006}, issn = {0924-669X}, month = apr, number = {No. 2}, pages = {109-125}, volume = {Vol. 24}, abstract = {Abstract Personalized delivery of multimedia content over the Internet opens new business perspectives for future multimedia applications and thus plays an important role in the ongoing MPEG-7 and MPEG-21 multimedia standardization efforts. Based on these standards, next-generation multimedia services will be able to automatically prepare the digital content before delivery according to the client’s device capabilities, the network conditions, or even the user’s content preferences. However, these services will have to deal with a variety of different end user devices, media formats, as well as with additional metadata when adapting the original media resources. In parallel, an increasing number of commercial or open-source media transformation tools will be available, capable of exploiting such descriptive metadata or dealing with new media formats; thus it is not realistic that a single tool will support all possible transformations. In this paper, we present a novel, fully knowledge-based approach for building such multimedia adaptation services, addressing the above mentioned issues of openness, extensibility, and concordance with existing and upcoming standards. In our approach, the original media is transformed in multiple adaptation steps performed by an extensible set of external tools, where the construction of adequate adaptation sequences is solved in an Artificial Intelligence planning process. The interoperability issue is addressed by exploiting standardized Semantic Web Services technology. This technology allows us to express tool capabilities and execution semantics in a declarative and well-defined form. In this context, existing multimedia standards serve as a shared domain ontology. The presented approach was implemented and successfully evaluated in an official ISO/IEC MPEG (Moving Picture Experts Group) Core Experiment and is currently under further evaluation by the standardization body.}, address = {Berlin, Heidelberg, New York}, language = {EN}, publisher = {Springer}, url = {http://www.springerlink.com/content/w745246635772v97/} } @Article{DeSutter2006a, author = {De Sutter, Robbie and Lerouge, Sam and De Neve, Peter and Timmerer, Christian and Hellwagner, Hermann and Van de Walle, Rik}, journal = {Multimedia Systems}, title = {Comparison of XML serializations: cost benefits versus complexity}, year = {2006}, month = oct, number = {Nr. 2}, pages = {101-115}, volume = {Vol. 12}, abstract = {More and more data are structured, stored, and sent over a networ using the Extensible Markup Language (XML) language. There are, however, concerns about the verbosity of XML in such a way that it may restrain further adoption of the language, especially when exchanging XML-based data over heterogeneous networks, and when it is used within constrained (mobile) devices. Therefore, alternative (binary) serialization formats of the XML data become relevant in order to reduce this overhead. However, using binary-encoded XML should not introduce interoperability issues with existing applications nor add additional complexity to new applications. On top of that, it should have a clear cost reduction over the current plain-text serialization format. A first technology is developed within the ISO/IEC Moving Picture Experts Group, namely the Binary MPEG Format for XML. It provides good compression efficiency, ability to (partially) update existingXMLtrees, and facilitates random access into, and manipulation of, the binary-encoded bit stream. Another technique is based on the Abstract Syntax Notation One specification with the Packed Encoding Rules created by the ITU-T. This paper evaluates both techniques as alternative XML serialization formats and introduces a solution for the interoperability concerns. This solution and the alternative serialization formats are validated against two real-life use cases in terms of processing speed and cost reduction. The efficiency of the alternative serialization formats are compared to a classic plain text compression technique, in particular ZIP compression.}, address = {Berlin, Heidelberg, New York}, doi = {10.1007/s00530-006-0044-y}, keywords = {XML serialization formats · MPEG-B · ASN.1 · Information encoding · Data interchange formats · Multimedia applications}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Comparison of XML serializations_cost benefits versus complexity.pdf}, publisher = {Springer} } @Article{DeSutter2006, author = {De Sutter, Robbie and Lerouge, Sam and De Neve, Peter and Timmerer, Christian and Hellwagner, Hermann and and Van de Walle, Rik}, journal = {ACM Multimedia Systems}, title = {Comparison of XML serializations: cost benefit vs. complexity}, year = {2006}, issn = {0942-4962}, month = aug, number = {No 1}, pages = {1-15}, volume = {Vol 12}, abstract = {More and more data are structured, stored, and sent over a networ using the Extensible Markup Language (XML) language. There are, however, concerns about the verbosity of XML in such a way that it may restrain further adoption of the language, especially when exchanging XML-based data over heterogeneous networks, and when it is used within constrained (mobile) devices. Therefore, alternative (binary) serialization formats of the XML data become relevant in order to reduce this overhead. However, using binary-encoded XML should not introduce interoperability issues with existing applications nor add additional complexity to new applications. On top of that, it should have a clear cost reduction over the current plain-text serialization format. A first technology is developed within the ISO/IEC Moving Picture Experts Group, namely the Binary MPEG Format for XML. It provides good compression efficiency, ability to (partially) update existingXMLtrees, and facilitates random access into, and manipulation of, the binary-encoded bit stream. Another technique is based on the Abstract Syntax Notation One specification with the Packed Encoding Rules created by the ITU-T. This paper evaluates both techniques as alternative XML serialization formats and introduces a solution for the interoperability concerns. This solution and the alternative serialization formats are validated against two real-life use cases in terms of processing speed and cost reduction. The efficiency of the alternative serialization formats are compared to a classic plain text compression technique, in particular ZIP compression.}, address = {London}, language = {EN}, publisher = {Springer} } @Article{Vetro2005, author = {Vetro, Anthony and Timmerer, Christian}, journal = {IEEE Transactions on Multimedia}, title = {Digital Item Adaptation: Overview of Standardization and Research Activities}, year = {2005}, issn = {1520-9210}, month = jun, pages = {418-426}, volume = {Special Issue on MPEG-21}, abstract = {MPEG-21 Digital Item Adaptation (DIA) has recently been finalized as part of the MPEG-21 Multimedia Framework. DIA specifies metadata for assisting the adaptation of Digital Items according to constraints on the storage, transmission and consumption, thereby enabling various types of quality of service management. This paper provides an overview of DIA, describes its use in multimedia applications, and reports on some of the ongoing activities in MPEG on extending DIA for use in rights governed environments.}, address = {Los Alamitos, CA, USA}, doi = {http://dx.doi.org/10.1109/TMM.2005.846795}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/01430717.pdf}, publisher = {IEEE} } @Article{Timmerer2005b, author = {Timmerer, Christian and Hellwagner, Hermann}, journal = {IEEE Multimedia Magazine}, title = {Interoperable Adaptive Multimedia Communication}, year = {2005}, month = jan, number = {1}, pages = {74-79}, volume = {12}, abstract = {Digital Item Adaptation (DIA) has been recently standardized as Part 7 of the MPEG-21 Multimedia Framework. This standard specifies tools enabling interoperable communication and adaptation of so-called Digital Items. The adaptation process becomes ever more difficult due to the heterogeneity of terminals and networks utilizing different types of multimedia contents encoded in various coding formats. Other aspects are the users� preferences and accessibility characteristics as well as the natural environment in which the content is consumed. This article describes how to use the tools within DIA in order to build a device and coding format independent adaptation module enabling interoperable multimedia communication.}, address = {Los Alamitos, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Interoperable Adaptive Multimedia Communication.pdf}, publisher = {IEEE Computer Society} } @Article{Schojer2005, author = {Schojer, Peter and Böszörmenyi, Laszlo and Hellwagner, Hermann}, journal = {Scalable Computing: Practice and Experience}, title = {An Adaptive Standard Meta-data Aware Proxy Cache}, year = {2005}, month = jul, number = {No 2}, pages = {93-104}, volume = {Vol 6}, abstract = {Multimedia is gaining ever more importance on the Internet. This increases the need for intelligent and efficient video caches. A promising approach to improve caching efficiency is to adapt videos. With the availability of MPEG-4 it is possible to develop a standard compliant proxy cache that allows fast and efficient adaptation. We propose a modular design for an adaptive MPEG-4 video proxy that supports efficient full and partial video caching in combination with filtering options that are driven by the terminal capabilities of the client. We use the native scalability operations provided by MPEG-4, the MPEG-7 standard to describe the scalability options for a video and the emerging MPEG-21 standard to describe the terminal capabilities. We restrict ourselves to full video caching. The combination of adaptation with MPEG-4, MPEG-7 and client terminal capabilities is to the best of our knowledge unique and will increase the quality of service for end users. Key words: Adaptation, MPEG-4, MPEG-7, MPEG-21, adaptive proxy, caching.}, address = {Timisoara, Romania}, language = {EN}, publisher = {SCPE} } @Article{Devillers2005, author = {Devillers, Sylvain and Timmerer, Christian and Heuer, Jörg and Hellwagner, Hermann}, journal = {IEEE Transactions on Multimedia}, title = {Bitstream Syntax Description-Based Adaptation in Streaming and Constrained Environments}, year = {2005}, month = jun, number = {No. 3}, pages = {463-470}, volume = {Special Issue on MPEG-21, Vol. 7}, abstract = {The seamless access to rich multimedia content on any device and over an network, usually known as Universal Multimedia Access, requires interoperable description tools and adaptation techniques to be developed. To address the latter issue, MPEG-21 Digital Item Adaptation (DIA) introduces the Bitstream Syntax Description (BSD) framework, which provides tools for adapting multimedia content in a generic (i.e., coding format independent) way. The basic idea is to use the eXtensible Markup Language (XML) to describe the high-level structure of a binary media bitstream, to transform its description (e.g., by means of eXtensible Stylesheet Language Transformations, XSLT), and to construct the adapted media bitstream from the transformed description. This paper presents how this basic BSD framework, initially developed for non-streamed content and suffering from inherent limitations and high memory consumption of XML-related technologies such as XSLT, can be advanced and efficiently implemented in a streaming environment and on resource-constrained devices. Two different attempts to solve the inherent problems are described. The first approach proposes an architecture based on the streamed processing of SAX (Simple Application Programming Interface for XML) events and adopts STX (Streaming Transformations for XML) as an alternative to XSLT, whereas the second approach breaks a BSD up into well-formed fragments called Process Units (PUs) that can be processed individually by a standard XSLT processor. The current status of our work as well as directions for future research are given.}, address = {Piscataway, USA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Bitstream Syntax Description-based Adaptation in Streaming and Constrained Environments.pdf}, publisher = {IEEE} } @Article{Tusch2004, author = {Tusch, Roland and Böszörmenyi, Laszlo and Goldschmidt, Balázs and Hellwagner, Hermann and Schojer, Peter}, journal = {Computer Science and Information Systems}, title = {Offensive and Defensive Adaptation in Distributed Multimedia Systems}, year = {2004}, month = {jan}, number = {No 1}, pages = {49-77}, volume = {Vol. 1}, abstract = {Adaptation in multimedia systems is usually restricted to defensive, reactive media adaptation (often called stream-level adaptation). We argue that offensive, proactive, system-level adaptation deserves not less attention. If a distributed multimedia system cares for overall, end-to-end quality of service then it should provide a meaningful combination of both. We introduce an adaptive multimedia server (ADMS) and a supporting middleware which implement offensive adaptation based on a lean, flexible architecture. The measured costs and benefits of the offensive adaptation process are presented. We introduce an intelligent video proxy (QBIX), which implements defensive adaptation. The cost/benefit measurements of QBIX are presented elsewhere. We show the benefits of the integration of QBIX in ADMS. Offensive adaptation is used to find an optimal, user-friendly configuration dynamically for ADMS, and defensive adaptation is added to take usage environment (network and terminal) constraints into account.}, address = {Novi Sad}, language = {EN}, publisher = {ComSIS} } @Article{Panis2003, author = {Panis, Gabriel and Hutter, Andreas and Heuer, Jörg and Hellwagner, Hermann and Kosch, Harald and Timmerer, Christian and Devillers, Sylvain and Amielh, Myriam}, journal = {Signal Processing: Image Communication}, title = {Bitstream Syntax Description: A Tool for Multimedia Resource Adaptation within MPEG-21}, year = {2003}, month = {jan}, number = {8}, pages = {721-747}, volume = {Vol. 18, Special Issue on Multimedia Adaptation}, abstract = {In this paper, a generic method is described to allow the adaptation of different multimedia resources by a single, media resource-agnostic processor. This method is based on an XML description of the media resource’s bitstream syntax, which can be transformed to reflect the desired adaptation and then be used to generate an adapted version of the bitstream. Based on this concept, two complementary technologies, BSDL and gBS Schema, are presented. The two technologies provide solutions for parsing a bitstream to generate its XML description, for the generic structuring of this description, and the generation of an adapted bitstream using its transformed description. The two technologies can be used as stand-alone tools; however, a joint approach has been developed in order to harmonise the two solutions and exploit their strengths. Since BSDL has been presented in previous publications, this paper is focusing more on the gBS Schema and the joint BSDL/gBS Schema approach.}, address = {Amsterdam, Netherlands}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/Bitstream syntax description.pdf}, publisher = {Elsevier B.V.} } @Article{Boeszoermenyi2003e, author = {Böszörmenyi, Laszlo and Kosch, Harald and Hellwagner, Hermann}, journal = {Parallel Processing Letters}, title = {Best papers of EuroPar 2003}, year = {2003}, issn = {0129-6264}, month = dec, number = {4}, pages = {509-511}, volume = {13}, address = {Heidelberg, Germany}, language = {EN}, publisher = {Springer} } @Article{Boeszoermenyi2003d, author = {Böszörmenyi, Laszlo and Hellwagner, Hermann and Kosch, Harald and Libsie, Mulugeta and Podlipnig, Stefan}, journal = {Signal Processing - Image Communication - Special Issue on Multimedia Adaptation}, title = {Metadata Driven Adaptation in the ADMITS Project}, year = {2003}, issn = {0923-5965}, month = sep, number = {Issue 8}, pages = {749-766}, volume = {Vol. 18}, abstract = {The ADMITS project (Adaptation in Distributed Multimedia IT Systems) is building an experimental distributed multimedia system for investigations into adaptation, which we consider is an increasingly important tool for multimedia systems. A number of possible adaptation entities (server, proxy, clients, routers) are being explored, different algorithms for media, component and application-level adaptations are being implemented and evaluated, and experimental data are being derived to gain insight into when, where and how to adapt, and how individual, distributed adaptation steps interoperate and interact with each other. In this paper the "adaptation-chain" of (MPEG-conforming) metadata based adaptation is described: from the creation stage at the server side, through its usage in the network (actually in a proxy), up to the consumption at the client. The metadata are used to steer the adaptation processes. MPEG-conformant metadata, the so-called variation descriptions, are introduced; an example of a complete MPEG-7 document describing temporal scaling of an MPEG-4 video is given. The meta-database designed to store the metadata is briefly discussed. We describe how the metadata can be extracted from MPEG-4 visual elementary streams and initial results from the temporal video scaling experiment are given. We further present how the metadata can be utilized by enhanced cache replacement algorithms in a proxy server in order to realize quality-based caching; experimental results using these algorithms are also given. Finally, an adaptive query and presentation interface to the meta-.}, address = {Oxford, United Kingdom}, language = {EN}, publisher = {Elsevier}, url = {http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%232003%23999819991%234} } @Article{Hellwagner2002a, author = {Hellwagner, Hermann and Ohlenroth, Matthias}, journal = {Future Generation Computer Systems}, title = {VI Architecture Communication Features and Performance on the Giganet Cluster LAN}, year = {2002}, issn = {0167-739X}, month = jan, number = {Issue 3}, pages = {421-433}, volume = {Vol. 18}, abstract = {The virtual interface (VI) architecture standard was developed to satisfy the need for a high throughput, low latency communication system required for cluster computing. VI architecture aims to close the performance gap between the bandwidths and latencies provided by the communication hardware and visible to the application, respectively, by minimizing the software overhead on the critical path of the communication. This paper presents the results of a performance study of one VI architecture hardware implementation, the Giganet cLAN (cluster LAN). The focus of the study is to assess and compare the performance of different VI architecture data transfer modes and specific features that are available to higher-level communication software like MPI in order to aid the implementor to decide which VI architecture options to employ for various communication scenarios. Examples of such options include the use of send/receive vs. RDMA data transfers, polling vs. blocking to check completion of communication operations, multiple VIs, completion queues and scatter capabilities of VI architecture.}, address = {Amsterdam, Netherlands}, doi = {http://dx.doi.org/10.1016/S0167-739X(01)00060-7}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/VI Architecture Communication Features and Performance on the Giganet Cluster LAN.pdf}, publisher = {Elsevier B.V.}, url = {http://www.sciencedirect.com/science/article/pii/S0167739X01000607} } @Article{Weiß2000, author = {Weiß, Christian and Hellwagner, Hermann and Stals, Linda and Rüde, Ulrich}, journal = {Concepts of Numerical Software}, title = {Data Locality Optimizations to Improve The Efficiency of Multigrid Methods}, year = {2000}, month = {jan}, pages = {1-10}, abstract = {Current superscalar microprocessors are able to operate at a peak performance of up to 1 GFlop/sec. However, current main memory technology does not provide the data needed fast enough to keep the CPU busy. To minimize idle times of the CPU, caches are used to speed up accesses to frequently used data. To exploit caches, the software must be aware of them and reuse data in the cache before it is being replaced. Unfortunately, all conventional multigrid codes are not cache-aware and hence exploit less than 10 percent of the peak performance of cache based machines. Our studies with linear PDEs with constant coefficients show that it is possible to speed up the execution of our multigrid method by a large factor and hence solve a Poisson’s equation with one million unknowns in less than 3 seconds. The optimized reuse of data in the cache allows us to exploit 30 percent of the peak performance of the CPU, in contrast to mgd9v for instance, which achieves less than 5 percent on the same machine. To achieve this, we used several techniques like loop unrolling and loop fusion to better exploit the memory hierarchy and the superscalar CPU. We study the effects of these techniques on the runtime performance in detail. We also study several tools which guide the optimizations and help to restructure the code.}, address = {NA}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/10.1.1.42.3070.pdf}, publisher = {NA} } @Article{Hellwagner1999b, author = {Hellwagner, Hermann and Zoraja, Ivan and Sunderam, Vaidy}, journal = {Concurrency: Practice and Experience}, title = {SCIPVM: Parallel Distributed Computing on SCI Workstation Clusters}, year = {1999}, issn = {1096-9128}, month = feb, number = {No 3}, pages = {121-138}, volume = {Vol 11}, abstract = {Workstation and PC clusters interconnected by SCI (Scalable Coherent Interface) are very promising technologies for high performance cluster computing. Using commercial SBus to SCI interface cards and early system software and drivers, a two-workstation cluster has been constructed for initial testing and evaluation. The PVM system has been adapted to operate on this cluster using raw device access to the SCI interconnect, and preliminary communications performance tests have been carried out. Our preliminary results indicate that communications throughput in the range of 3.5 MBytes/s, and latencies Research supported by the Applied Mathematical Sciences program, Office of Basic Energy Sciences, U. S. Department of Energy, under Grant No. DE-FG05-91ER25105, the National Science Foundation, under Award Nos. ASC-9527186 and ASC-9214149, and the German Science Foundation SFB342. of 620 ¯s can be achieved on SCI clusters. These figures are significantly better (by a factor of 3 to 4) ...}, address = {N, A}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/10.1.1.41.2639.pdf}, publisher = {N, A} } @Article{Mayerle1997a, author = {Mayerle, Wolfgang and Hellwagner, Hermann}, journal = {Praxis der Informationsverarbeitung und Kommunikation}, title = {Konzepte und funktionaler Vergleich von Thread-Systemen (2)}, year = {1997}, issn = {0930-5157}, month = oct, number = {4}, pages = {225-229}, volume = {20}, address = {Mannheim, Germany}, language = {DE}, publisher = {Spani} } @Article{Mayerle1997, author = {Mayerle, Wolfgang and Hellwagner, Hermann}, journal = {Praxis der Informationsverarbeitung und Kommunikation}, title = {Konzepte und funktionaler Vergleich von Thread-Systemen (1)}, year = {1997}, issn = {0930-5157}, month = {jan}, pages = {164-174}, volume = {20}, abstract = {Dieses Papier gibt eine allgemeine Einführung in Threads und vergleicht einige derzeit für Arbeitsplatzrechner erhältliche Thread-Systeme. Aufbauend auf einer Motivation und grundlegenden Erläuterung des Thread-Konzepts werden wichtige Aspekte und Probleme von Thread-Bibliotheken vorgestellt. Nach einigen Hinweisen zur Programmierung mit Threads werden mehrere Implementierungen einander gegenübergestellt.}, address = {Mannheim, Germany}, language = {DE}, pdf = {https://www.itec.aau.at/bib/files/1997-0048-MaHe.pdf}, publisher = {Spaniol, Otto} } @Article{Hellwagner1997e, author = {Hellwagner, Hermann and Karl, Wolfgang and Leberecht, Markus}, journal = {Speedup Journal, Proceedings, 21st Workshop, March 13-14, 1997, Cadro-Lugano}, title = {Enabling a PC Cluster for High-Performance Computing}, year = {1997}, month = jun, number = {1}, pages = {18-23}, volume = {Vol. 11}, abstract = {Due to their excellent cost/performance ratio, clusters of PCs can be attractive high-performance computing (HPC) platforms. Yet, their limited communication performance over standard LANs is still prohibitive for parallel applications. The project "Shared Memory in a LAN-like Environment" (SMiLE) at LRR-TUM adopts Scalable Coherent Interface (SCI) interconnect technology to build, and provide software for, a PC cluster which, with hardware-based distributed shared memory (DSM) and high-performance communication characteristics, is regarded as well suited for HPC. The paper describes the key features of the enabling technology, SCI. It then discusses the developments and important results of the SMiLE project so far: the development and initial performance of a PCI/SCI interface card, and the design and initial performance results of low-latency communication layers, Active Messages and a sockets emulation library.}, address = {N, A}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/1997-0049-HeKL.pdf}, publisher = {N, A} } @Article{Boeckle1996a, author = {Böckle, Günter and Hellwagner, Hermann and Lepold, Roland and Sandweg, Gerd and Schallenberger, Burghardt and Thudt, Raimar and and Wallstab, Stefan}, journal = {IEEE Computer Society}, title = {Structured Evaluation of Computer Systems}, year = {1996}, issn = {0018-9162}, month = jun, number = {No 6}, pages = {45-51}, volume = {Vol. 29}, abstract = {Evaluating computers and other systems is difficult for a couple of reasons. First, the goal of evaluation is typically ill-defined: customers, sometimes even designers, either don't know or can't specify exactly what result they expect. Often, they don't specify the architectural variants to consider, and often the metrics and workload they expect you to use are ill-defined. Second, they rarely clarify which kind of model and evaluation method best suit the evaluation problem. These problems have consequences. For one thing, the decision-maker may not trust the evaluation. For another, poor planning means the evaluation cannot be reproduced if any of the parameters are changed slightly. Finally, the evaluation documentation is usually inadequate, and so some time after the evaluation you might ask yourself, how did I come to that conclusion? An approach developed at Siemens makes decisions explicit and the process reproducible}, address = {N, A}, doi = {http://dx.doi.org/10.1109/2.507631}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/00507631.pdf}, publisher = {N, A} } @Article{Hellwagner1993, author = {Hellwagner, Hermann}, journal = {The Computer Journal - Parallel Processing}, title = {Design Considerations for Scalable Parallel File Systems}, year = {1993}, month = {jan}, number = {8}, pages = {741-755}, volume = {Vol. 36}, abstract = {This paper addresses the problem of providing high-performance disk I/O in massively parallel computers. Resolving the fundamental I/O bottleneck in parallel architectures involves both hardware and software issues. We review previous work on disk arrays and I/O architectures aimed at providing highly parallel disk I/O subsystems. We then focus on the requirements and design of parallel file systems (PFSs) which are responsible to make the parallelism offered by the hardware and a declustered file organization available to application programs. We present the design strategy and key concepts of a general-purpose file system for a parallel computer with scalable distributed shared memory. The principal objectives of the PFS are to fully exploit the parallelism inherent among and within file accesses, and to provide scalable I/O performance. The machine model underlying the design is described, with and emphasis on the innovative architectural features supporting scalability of the shared memory. Starting from a classification of various scenarios of concurrent I/O requests, the features of the PFS design essential for achieving the goals are described and justified. It is argued that the inter- and intra-request parallelism of the I/O load can indeed be effectively exploited and supported by the parallel system resources. Scalability of I/O performance and of the PFS software can be ensured by avoiding serial bottlenecks through the use of the powerful architectural features.}, address = {N, A}, language = {EN}, pdf = {https://www.itec.aau.at/bib/files/741.full.pdf}, publisher = {N, A} }