Publications of Wolfgang Effelsberg

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Philipp Schaber, Stephan Kopf, Sina Wetzel, Tyler Ballast, Christoph Wesch und Wolfgang Effelsberg. 2015 CamMark: Analyzing, Modeling, and Simulating Artifacts in Camcorder Copies ACM Transactions on Multimedia Computing, Communications, and applications : TOMCCAP, 11, 10, Article 42, 1-23
To support the development of any system that includes the generation and evaluation of camcorder copies, as well as to provide a common benchmark for robustness against camcorder copies, we present a tool to simulate digital video re-acquisition using a digital video camera. By resampling each video frame, we simulate the typical artifacts occurring in a camcorder copy: geometric modifications (aspect ratio changes, cropping, perspective and lens distortion), temporal sampling artifacts (due to different frame rates, shutter speeds, rolling shutters, or playback), spatial and color subsampling (rescaling, filtering, Bayer color filter array), and processing steps (automatic gain control, automatic white balance). We also support the simulation of camera movement (e.g., a hand-held camera) and background insertion. Furthermore, we allow for an easy setup and calibration of all the simulated artifacts, using sample/reference pairs of images and videos. Specifically temporal subsampling effects are analyzed in detail to create realistic frame blending artifacts in the simulated copies. We carefully evaluated our entire camcorder simulation system and found that the models we developed describe and match the real artifacts quite well.

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Okan Aydingül, Philip Mildner, Stephan Kopf und Wolfgang Effelsberg. Association for the Advancement of Computing in Education (AACE), 2015 EOOC - Easy Open Online Courses : a platform to create and run open online courses . Waynesville, NC
Stephan Kopf, Daniel Schön, Benjamin Guthier, Roman Rietsche und Wolfgang Effelsberg. Association for the Advancement of Computing in Education (AACE), 2015 A real-time feedback system for presentation skills . Waynesville, NC
Philip Mildner, Nicolas Stamer und Wolfgang Effelsberg. Springer International Publishing, 2015 From game characteristics to effective learning games : evaluation of a component-based quiz game Lecture Notes in Computer Science. Cham [u.a.]When developing learning games, emphasis should not only be put on a good integration of the learning content, but also on an engaging game design, in order to create learning tools that both train and motivate. In this paper, we examine the influence of specific game elements to both factors. Therefore, we first analyze models for the characterization of game elements. We then apply an adapted model to the design of a component-based learning game based on a quiz. Various game elements can be added to the game dynamically. This includes, among others, different forms of presentation, challenge, competition and constraints. Using this application we performed a user study to evaluate which game elements are most effective in delivering knowledge as well as in fostering motivation. Results show that a combination of game elements is suited best for influencing both factors positively.
Simone Paolo Ponzetto, Hartmut Wessler, Lydia Weiland, Stephan Kopf, Wolfgang Effelsberg und Heiner Stuckenschmidt. Peter Lang Edition, 2015 Automatic classification of iconic images based on a multimodal model : an interdisciplinary project Sprache - Medien - Innovationen. Frankfurt am Main ; Bern; Wien
Philipp Schaber, Sally Dong, Benjamin Guthier, Stephan Kopf und Wolfgang Effelsberg. ACM, 2015 Modeling temporal effects in re-captured video . New York, NYThe re-capturing of video content poses significant challenges to algorithms in the fields of video forensics, watermarking, and near-duplicate detection. Using a camera to record a video from a display introduces a variety of artifacts, such as geometric distortions, luminance transformations, and temporal aliasing. A deep understanding of the causes and effects of such phenomena is required for their simulation, and for making the affected algorithms more robust. In this paper, we provide a detailed model of the temporal effects in re-captured video. Such effects typically result in the re-captured frames being a blend of the original video's source frames, where the specific blend ratios are difficult to predict. Our proposed parametric model captures the temporal artifacts introduced by interactions between the video renderer, display device, and camera. The validity of our model is demonstrated through experiments with real re-captured videos containing specially marked frames.
Matthias Schulz, Denny Stohr, Stefan Wilk, Benedikt Rudolph, Wolfgang Effelsberg und Matthias Hollick. IEEE, 2015 APP and PHY in harmony: a framework enabling flexible physical layer processing to address application requirements . Piscataway, NJ
Daniel Schön, Melanie Klinger, Stephan Kopf und Wolfgang Effelsberg. SCITEPRESS, Science and Technology Publications, 2015 A model for customized in-class learning scenarios - an approach to enhance audience response systems with customized logic and interactivity . [Setúbal]
Daniel Schön, Licheng Yang, Melanie Klinger, Stephan Kopf und Wolfgang Effelsberg. Assoc. for the Advancement of Computing in Education , Universität Mannheim 2015 On the effects of different parameters in classroom interactivity systems on students . Waynesville, NCClassroom Response Systems (CRS) are often used in higher education lectures. They help to activate students and to get a deeper insight on the students' knowledge base and on their opinion on currently discussed topics. Many different systems were created, offering a similar amount of functionality. We thus investigate what the important parameters of such systems are, and how they influence the students’ behavior. Therefore, we consider classic response systems as well as systems with a higher amount of interactivity. In a first step, we have defined eight possible parameters, like the usage of pictures or a progress bar. We did a field study in thirty six lectures comparing the impact of the different parameters. As expected, the overall satisfaction with CRS is very high but we have obtained surprising results with particular parameters. We present the most interesting results and give a suggestion on which parameters are useful for an investigation in greater depth.
Denny Stohr, Tao Li, Stefan Wilk, Silvia Santini und Wolfgang Effelsberg. EEE Operations Center, 2015 An analysis of the YouNow live streaming platform . Piscataway, NJ
Denny Stohr, Matthias Schulz, Matthias Hollick und Wolfgang Effelsberg. IEEE, 2015 APP and PHY in harmony: demonstrating scalable video streaming supported by flexible physical layer control . Piscataway, NJ
Stefan Wilk, Stephan Kopf und Wolfgang Effelsberg. ACM, 2015 Video composition by the crowd : a system to compose user-generated videos in near real-time . New York, NY
Stefan Wilk, Julius Rückert, Denny Stohr, Björn Richerzhagen und Wolfgang Effelsberg. IEEE, 2015 Efficient video streaming through seamless transitions between unicast and broadcast . Piscataway, NJ
Stefan Wilk, Julius Rückert, Timo Thräm, Christian Koch, Wolfgang Effelsberg und David Hausheer. IEEE, 2015 The potential of social-aware multimedia prefetching on mobile devices . Piscataway, NJ
Stefan Wilk, Sophie Schönherr, Denny Stohr und Wolfgang Effelsberg. ACM, 2015 EnvDASH: an environment-aware dynamic adaptive streaming over HTTP systems . New York, NY
Stefan Wilk, Denny Stohr und Wolfgang Effelsberg. ACM, 2015 VAS: a video adaptation service to support mobile video . New York, NY
Stefan Wilk, Dimitri Wulffert und Wolfgang Effelsberg. IEEE, 2015 On influencing mobile live video broadcasting users . Piscataway, NJ

Publications of Wolfgang Effelsberg

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