Peter Schojer

The life cycle of multimedia metadata

During its lifetime, multimedia content undergoes different stages or cycles from production to consumption. Content is created, processed or modified in a postproduction stage, delivered to users, and finally, consumed. Metadata, or descriptive data about the multimedia content, pass through similar stages but with different time lines. Metadata may be produced, modified, and consumed by all actors involved in the content production-consumption chain. At each step of the chain, different kinds of metadata may be produced by highly different methods and of substantially different semantic value. Different metadata let us tie the different multimedia processes in a life cycle together. However, to employ these metadata, they must be appropriately generated. The CODAC Project, led by Harald Kosch, implements different multimedia processes and ties them together in the life cycle. CODAC uses distributed systems to implement multimedia processes. The projects core component is a multimedia database management system (MMDBMS) which stores content and MPEG-7-based metadata. It communicates with a streaming server for data delivery. The database is realized in the multimedia data cartridge (MDC) - which is an extension of the Oracle database management system - to handle multimedia content and MPEG-7 metadata.

Comprehensive treatment of adaptation in distributed multimedia systems in the ADMITS project

Adaptation is becoming an increasingly important tool for re-source and media management in distributed multimedia systems. Best-effort scheduling and worst-case reservation of resources are two extreme cases, none of them well suited to cope with large-scale, dynamic multimedia systems. The middle course can be met by a system which dynamically adapts its data, resource re-quirements, and processing components to achieve user satisfac-tion. Nevertheless, there is no agreement about the questions, where, when, what and who should adapt. A number of papers have been published in recent years, where adaptation is a central issue, however, in most different interpretations and generally in a somehow limited scope; e.g.,[1, 2, 8, 9, 10, 12]. A distributed multimedia system comprises several types of com-ponents, such as media servers, meta-databases, proxies, routers, clients. Also, a large number of adaptation possibilities exist, from simple frame dropping up to virtual server systems which dynamically allocate new resources on demand. The main ques-tion is, which kind of component can be best used for what kind of adaptation. In the

Metadata-driven optimal transcoding in a multimedia proxy

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 You Get (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.

QBIX-G: a transcoding multimedia proxy

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 in the decompressed domain. A cost model is presented which incorporates user requirements, terminal apabilities, 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 You Get (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.

An Adaptive MPEG-4 Proxy Cache

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 that allows fast and efficient adaptation.

Modular Programming Languages

Only a few years after the invention of the first programming languages, the subject flourished and a whole flurry of languages appeared. Soon programmers had to make their choices among available languages. How were they selected; were there any criteria of selection, of language quality? What is truly essential in a programming language? In spite of the convergence to a few, wide-spread, popular languages in recent years, these questions remain relevant, and the search for a “better” language continues among programmers.