[2] | Christian Timmerer, Gabriel Panis, Harald Kosch, Jörg Heuer, Hermann Hellwagner, Andreas Hutter, Coding format independent multimedia content adaptation using XML, In Proceedings of SPIE International Symposium ITCom 2003 on Internet Multimedia Managment Systems IV, Vol. 5242 (A N, ed.), SPIE Press, Orlando, pp. 92-103, 2003.
[bib] [pdf] [abstract]
Abstract: Due to the heterogeneity of the current terminal and network infrastructures, multimedia content needs to be adapted to specific capabilities of these terminals and network devices. Furthermore, user preferences and user environment characteristics must also be taken into consideration. The problem becomes even more complex by the diversity of multimedia content types and encoding formats. In order to meet this heterogeneity and to be applicable to different coding formats, the adaptation must be performed in a generic and interoperable way. As a response to this problem and in the context of MPEG-21, we present an approach which uses XML to describe the high-level structure of a multimedia resource in a generic way, i.e., how the multimedia content is organized, for instance in layers, frames, or scenes. For this purpose, a schema for XML-based bitstream syntax descriptions (generic Bitstream Syntax Descriptions or gBSDs) has been developed. A gBSD can describe the high-level structure of a multimedia resource in a coding format independent way. Adaptation of the resource is based on elementary transformation instructions formulated with respect to the gBSDs. These instructions have been separated from the gBSDs in order to use the same descriptions for different adaptations, e.g., temporal scaling, SNR scaling, or semantic adaptations. In the MPEG-21 framework, those adaptations can be steered for instance by the network characteristics and the user preferences. As a result, it becomes possible for coding format agnostic adaptation engines to transform media bitstreams and associated descriptions to meet the requirements imposed by the network conditions, device capabilities, and user preferences.
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[1] | Peter Schojer, Laszlo Böszörmenyi, Hermann Hellwagner, An Adaptive MPEG-4 Proxy Cache, In Distributed and parallel systems: cluster and grid computing. Proceedings of International Conference on Distributed and Parallel Systems (DAPSYS 02), Linz, Austria. (Péter Kascuk, Dieter Kranzlmüller, Zsolt Németh, Jens Volkert, eds.), Kluwer Academic Publishers, Boston [u. a.], pp. 149-156, 2002.
[bib] [pdf] [abstract]
Abstract: Multimedia is gaining ever more importance on the Internet. This increases the need for intelligent and efficient video caches. Typical Web proxies were not designed to efficiently support the caching of videos. 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 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 and use the emerging MPEG-7 standard to describe the scalability options for a video. The proxy parses the MPEG-7 description and decides, based on this description and the terminal capabilities of the client, which adaptation step to choose. Simple MPEG-4 audio-visual streams are supported by filter operations in the compressed domain that realize several temporal scaling algorithms and color reduction. In this paper, we will 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.
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