C03: Content-centred perspective

TP C03 is responsible for the design and development of an adaptive video streaming application, which is an essential building block for demonstrating the concepts of MAKI. One of the major problems addressed in this TP is the challenge of scalable, decentralized storage and distribution of video content. Especially in the context of continuously changing environmental conditions, existing solutions are very limited to address a fixed conditions but the replacement of mechanisms during runtime is still an open and challenging issue.

TP C03 is of significant importance for MAKI on many levels: C03 determines fundamental requirements and models for transition-capable communication systems that build the foundation for research in projects A and B. In addition specific transitions between mechanisms on the application layer are evaluated that allow the implementation of an adaptive video streaming application. Here, methods developed in the A- and B-projects are essential for the design of this adaptive video streaming application. Based on this implementation, a further refinement of the methods developed in the A and B projects is to be achieved. Therefore, C03 provides insights on the realization of adaptive video streaming applications that go far beyond the boundaries of existing approaches.

Motivation for the research conducted in C03 is the observation that modern devices are increasingly able to display high resolution content and devices such as smartphones, notebooks and tablets are, by default, equipped with a mass of different sensors, e.g. cameras. It is therefore natural to assume that in future videos are increasingly produced decentralized and directly published by users using existing wireless infrastructure. Especially in the context of MAKI, mobile social applications are a reason for this increasing demand of video content. Yet networks and mechanisms will not be able to cope with this challenge of a massively increased utilization of the existing networks.

In order to develop an adaptive video streaming application C03 defines new structures, algorithms and protocols to address innovative aspects of decentralized storage and distribution of videos. These aspects will be introduced in four prototypical implementations: First, scalable video streaming on the basis of the H.264 SVC (Scalable Video Streaming) standard. Secondly, video distribution mechanisms that respect a heterogeneous device landscape with alternating bandwidths. Thirdly, the combination of Peer-to-Peer (P2P) driven video dissemination and classical server-based distribution. And last, the intelligent prefetching of video content.

To evaluate the adaptive playback depending on the available network resources we plan to use the reference implementation of H.264 SVC of the Fraunhofer Heinrich-Hertz-Institute. For the distribution of videos, alternative distribution mechanisms are researched, starting from mesh- and tree-based overlays which adapt according to the current environmental conditions. In addition mechanisms for dynamic allocation of server resources are developed to allow scalable and decentralized requests of an adaptive video. Last, the development of intelligent prefetching mechanisms aims on the reduction of the startup delay. This prefetching of videos could be for example based upon the rank in social groups such as in Online Social Networks.

In summary C03 contributes an important and sustainable application for transition-capable communication networks to MAKI, which has a significant impact on different layers. For instance, the transition from mesh- to tree-based topology or from Server- to P2P-based distribution will have a direct impact on the throughput in lower layers. Vice versa a transition on lower layers, like the adaptation of an infrastructure-based to an Ad-hoc based communication, may result in a different streaming mechanism in C03.

• Prof. Dr.-Ing. Wolfgang Effelsberg
• Prof. Dr.-Ing. Ralf Steinmetz