[331] | Christian Timmerer, MPEG column: 121st MPEG meeting in Gwangju, Korea, In SIGMultimedia Records, ACM, vol. 10, no. 1, New York, NY, USA, pp. 6:6-6:6, 2018.
[bib][url] [doi] |
[330] | Christian Timmerer, MPEG Column: 120th MPEG Meeting in Macau, China, In SIGMultimedia Records, ACM, vol. 9, no. 3, New York, NY, USA, pp. 4:4-4:4, 2018.
[bib][url] [doi] |
[329] | Evsen Yanmaz, Saeed Yahyanejad, Bernhard Rinner, Hermann Hellwagner, Christian Bettstetter, Drone networks: Communications, coordination, and sensing, In Ad Hoc Networks, Elsevier, vol. 68, Amsterdam, pp. 1-15, 2018.
[bib][url] [doi] [abstract]
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.
|
[328] | Daniela Pohl, Abdelhamid Bouchachia, Hermann Hellwagner, Batch-based active learning: Application to social media data for crisis management, In Expert Systems with Applications, Elsevier Ltd., vol. 93, Amsterdam, pp. 232-244, 2018.
[bib][url] [doi] [abstract]
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.
|
[327] | Harald Beck, Bruno Bierbaumer, Minh Dao-Tran, Thomas Eiter, Hermann Hellwagner, Konstantin Schekotihin, Stream Reasoning-Based Control of Caching Strategies in CCN Routers, In Communications (ICC), 2017 IEEE International Conference on (Jean Luc Beylat, Hikmet Sari, eds.), IEEE, Paris, France, pp. 6, 2017.
[bib] [doi] [abstract]
Abstract: Routers in Content-Centric Networking (CCN) may locally cache frequently requested content in order to speed up delivery to end users. Thus, the issue of caching strategies arises, i.e., which content shall be stored and when it should be replaced. In this work, we employ, and study the feasibility of, novel techniques towards intelligent control of CCN routers that autonomously switch between existing caching strategies in response to changing content request patterns. In particular, we present a router architecture for CCN networks that is controlled by rule-based stream reasoning, following the recent formal framework LARS which extends Answer Set Programming for streams. The obtained possibility for flexible router configuration at runtime allows for versatile network control schemes and may help advance the further development of CCN. Moreover, the empirical evaluation of our feasibility study shows that the resulting caching agent may give significant performance gains.
|
[326] | Anatoliy Zabrovskiy, Evgeny Petrov, Evgeny Kuzmin, Christian Timmerer, Evaluation of the Performance of Adaptive HTTP Streaming Systems, In arXiv.org [cs.MM], N.N., vol. abs/1710.02459, N.N., pp. 7, 2017.
[bib][url] [pdf] [abstract]
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.
|
[325] | Anatoliy Zabrovskiy, Evgeny Kuzmin, Evgeny Petrov, Christian Timmerer, Christopher Mueller, AdViSE: Adaptive Video Streaming Evaluation Framework for the Automated Testing of Media Players, In Proceedings of the 8th ACM on Multimedia Systems Conference (MMSys'17) (Kuan-Ta Chen, ed.), ACM, New York, NY, USA, pp. 4, 2017.
[bib] [doi] [pdf] [abstract]
Abstract: Today we can observe a plethora of adaptive video stream- ing services and media players which support interoperable formats like DASH and HLS. Most of the players and their rate adaptation algorithms work as a black box. We have de- veloped a system for easy and rapid testing of media players under various network scenarios. In this paper, we introduce AdViSE, the Adaptive Video Streaming Evaluation frame- work for the automated testing of adaptive media players. The presented framework is used for the comparison and testing of media players in the context of adaptive video streaming over HTTP in web/HTML5 environments. The demonstration showcases a series of experiments with different media players under given context conditions (e.g., network shaping, delivery format). We will also demonstrate the real-time capabilities of the framework and offline anal- ysis including several QoE metrics with respect to a newly introduced bandwidth index.
|
[324] | Christian Timmerer, Immersive Media Delivery: Overview of Ongoing Standardization Activities, In IEEE Communications Standards Magazine, IEEE Communications Society, vol. 1, no. 4, N.N., pp. 71-74, 2017.
[bib] [doi] [pdf] [abstract]
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.
|
[323] | Christian Timmerer, Ali Cengiz Begen, Advancing Multimedia Content Distribution, In Computing Now, IEEE Computer Society [online], Los Alamitos, CA, USA, pp. 1, 2017.
[bib][url] |
[322] | Christian Timmerer, MPEG Column: 116th MPEG Meeting, In SIGMultimedia Records, ACM, vol. 8, no. 4, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[321] | Christian Timmerer, MPEG Column: 117th MPEG Meeting, In SIGMultimedia Records, ACM, vol. 9, no. 1, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[320] | Christian Timmerer, MPEG Column: 118th MPEG Meeting, In SIGMultimedia Records, ACM, vol. 8, no. 4, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[319] | Christian Timmerer, MPEG Column: 119th MPEG Meeting in Turin, Italy, In SIGMultimedia Records, ACM, vol. 9, no. 2, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[318] | Christian Timmerer, Report from ACM MMSys 2017, In SIGMultimedia Records, ACM, vol. 9, no. 2, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[317] | Christian Timmerer, Anatoliy Zabrovskiy, Evgeny Kuzmin, Evgeny Petrov, Quality of experience of commercially deployed adaptive media players, In 2017 21st Conference of Open Innovations Association (FRUCT) (Sergey Balandin, ed.), N.N., N.N., pp. 330-335, 2017.
[bib] [doi] [pdf] [abstract]
Abstract: In the past decade we observed the transition from push-based, fully managed media streaming to pull-based, unmanaged adaptive HTTP streaming thanks to enhancements in media compression, network capacity, and client capabilities. Adaptive media players, specifically their algorithms, have been subject to research for a long time and lead to various approaches documented in the literature. In the past years we witnessed more and more commercial deployments taking into account findings presented in scientific papers but a quantitative evaluation and assessments of its performance is missing. In this paper, we propose means for the automated performance evaluation of commercially deployed adaptive media players with respect to i) objective, well-known metrics, such as bitrate, stalls, startup delay and ii) derived/calculated metrics (instability, inefficiency, average bitrate) previously proposed in the literature. Additionally, we propose a new metric (Bandwidth index) to measure the effectiveness of bandwidth utilization and together with existing QoE models for adaptive HTTP streaming (focusing on stalls, startup delay) we demonstrate its usefulness in this domain.
|
[316] | Christian Timmerer, Ali Cengiz Begen, 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, In ACM Transactions on Multimedia Computing, Communications, and Applications (TOMM), ACM Digital Library, vol. 13, no. 3s, New York, NY, USA, pp. 40:1-40:2, 2017.
[bib][url] [doi] [pdf] |
[315] | Christian Timmerer, Mario Graf, Christopher Mueller, Adaptive Streaming of VR/360-degree Immersive Media Services with high QoE, In 2018 NAB Broadcast Engineering and IT Conference (BEITC) (not available, ed.), National Association of Broadcasters (NAB), Washington DC, USA, pp. 5, 2017.
[bib] [pdf] |
[314] | Raimund Schatz, Andreas Sackl, Christian Timmerer, Bruno Gardlo, Towards Subjective Quality of Experience Assessment for Omnidirectional Video Streaming, In 2017 Ninth International Conference on Quality of Multimedia Experience (QoMEX) (Alexander Raake, ed.), IEEE, New York, USA, pp. 6, 2017.
[bib] [doi] [pdf] [abstract]
Abstract: Currently, we witness dramatically increasing interest in immersive media technologies like Virtual Reality (VR), particularly in omnidirectional video (OV) streaming. Omnidirectional (also called 360-degree) videos are panoramic spherical videos in which the user can look around during playback and which therefore can be understood as hybrids between traditional movie streaming and interactive VR worlds. Unfortunately, streaming this kind of content is extremely bandwidth intensive (compared to traditional 2D video) and therefore, Quality of Experience (QoE) tends to deteriorate significantly in absence of continuous optimal bandwidth conditions. In this paper, we present a first approach towards subjective QoE assessment for omnidirectional video (OV) streaming. We present the results of a lab study on the QoE impact of stalling in the context of OV streaming using head-mounted displays (HMDs). Our findings show that subjective testing for immersive media like OV is not trivial, with even simple cases like stalling leading to unexpected results. After a discussion of characteristic pitfalls and lessons learned, we provide a a set of recommendations for upcoming OV assessment studies.
|
[313] | Benjamin Rainer, Stefan Petscharnig, Christian Timmerer, Hermann Hellwagner, Statistically Indifferent Quality Variation: An Approach for Reducing Multimedia Distribution Cost for Adaptive Video Streaming Services, In IEEE Transactions on Multimedia, IEEE, vol. 19, New York, USA, pp. 13, 2017.
[bib][url] [doi] [pdf] [abstract]
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.
|
[312] | Daniel Posch, Benjamin Rainer, Hermann Hellwagner, SAF: Stochastic Adaptive Forwarding in Named Data Networking, In IEEE/ACM Transactions on Networking, IEEE, vol. 25, no. 2, New York, USA, pp. 14, 2017.
[bib][url] [doi] [pdf] [abstract]
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.
|
[311] | Daniel Posch, Benjamin Rainer, Hermann Hellwagner, Towards a Context-Aware Forwarding Plane in Named Data Networking supporting QoS, In Computer Communication Review, ACM SIGCOMM, vol. 47, no. 1, New York, USA, pp. 9, 2017.
[bib][url] [doi] [pdf] [abstract]
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.
|
[310] | Antonio Pinheiro, Christian Timmerer, Standards Column: JPEG and MPEG, In SIGMultimedia Records, ACM, vol. 9, no. 1, New York, NY, USA, pp. N.N., 2017.
[bib][url] [doi] |
[309] | Philipp Moll, Daniel Posch, Hermann Hellwagner, Investigation of push-based traffic for conversational services in Named Data Networking, In Proceedings of the IEEE International Conference on Multimedia and Expo Workshops (ICMEW) 2017 (Beatrice Pesquet-Popescu, Chong-Wah Ngo, eds.), IEEE, Hong Kong, pp. 315-320, 2017.
[bib][url] [doi] [pdf] [abstract]
Abstract: Conversational services (e.g., Internet telephony) exhibit hard Quality of Service (QoS) requirements, such as low delay and jitter. Current IP-based solutions for conversational services use push-based data transfer only, since pull-based communication as envisaged in Named Data Networking (NDN) suffers from the two-way delay. Unfortunately, IP's addressing scheme requires additional services for contacting communication partners. NDN provides an inherent solution for this issue by using a location-independent naming scheme. Nevertheless, it currently does not provide a mechanism for push-based data transfer. In this paper, we investigate Persistent Interests as a solution for push-based communication. We improve and implement the idea of Persistent Interests, and study their applicability for conversational services in NDN. This is done by comparing different push- and pull-based approaches for Internet telephony.
|
[308] | Philipp Moll, Julian Janda, Hermann Hellwagner, Adaptive Forwarding of Persistent Interests in Named Data Networking, In Proceedings of the 4th ACM Conference on Information-Centric Networking (Thomas C Schmidt, Jan Seedorf, eds.), ACM, New York, NY, USA, pp. 180-181, 2017.
[bib][url] [doi] [pdf] [abstract]
Abstract: Persistent Interests (PIs) are a promising approach to introduce push-type traffic in Named Data Networking (NDN), in particular for conversational services such as voice and video calls. Forwarding decisions for PIs are crucial in NDN because they establish a long-lived path for the data flowing back toward the PI issuer. In the course of studying the use of PIs in NDN, we investigate adaptive PI forwarding and present a strategy combining regular NDN forwarding information and results from probing potential alternative paths through the network. Simulation results indicate that our adaptive PI forwarding approach is superior to the PI-adapted Best Route strategy when network conditions change due to link failures.
|
[307] | X Zhu, S Mao, M Hassan Hassan, Hermann Hellwagner, Guest Editorial: Video Over Future Networks, In IEEE Transactions on Multimedia, IEEE, vol. 19, no. 10, Piscataway, NJ, pp. 2133 - 2135, 2017.
[bib][url] [doi] [abstract]
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.
|