Abstract: Adaptation is usually restricted to defensive, reactive media adaptation (often called stream-level adaptation). We argue that offensive, proactive, system-level adaptation deserves not less attention. If a distributed multimedia system cares for overall, end-to-end quality of service then it should provide a meaningful combination of both. We introduce an adaptive multimedia server (ADMS) and a supporting middleware which implement offensive adaptation based on a lean, flexible architecture. The measured costs and benefits of the offensive adaptation process are presented. We introduce an intelligent video proxy (QBIX), which implements defensive adaptation. The cost/benefit measurements of QBIX are presented elsewhere \citeSchojer03. We show the benefits of the integration of QBIX in ADMS. Offensive adaptation is used to find an optimal, user-friendly configuration dynamically for ADMS, and defensive adaptation is added to take usage environment (network and terminal) constraints into account.

Abstract: Abstract. This paper presents an adaptive distributed multimedia streaming server architecture (ADMS) which explicitly controls the serverlayout. It consists of four types of streaming server components, which all provide dedicated services in an arbitrary number of instances on an arbitrary number of server hosts. Vagabond2 is used as the underlying middleware for component adaptation. It is shown, how the CORBA-based components have to be declared in order to run on top of Vagabond2. Finally, inter-component dependencies are pointed out, which have to be taken into account during component adaptations.

Abstract: We present an adaptive distributed multimedia server architecture (ADMS) that builds upon the idea of offensive adaptivity, where the server proactively controls its layout through replication or migration of server components to recommended hosts. Proactive actions are taken when network or server resources become critical when fulfilling client demands. Recommendations are provided by a so-called “host recommender” which represents an integral part of Vagabond2 - the middleware used for component distribution. Recommendations are based on measured or estimated server and network resource availabilities. Network distance and host resource metrics - obtained from network and host resource services respectively - may be communicated as MPEG-21 DIA descriptors. Finally we evaluate our architecture in a real-world streaming scenario.

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.

Abstract: Due to the increasing availability and use of digital video data on the Web, video caching will be an important performance factor in the future WWW. We propose an architecture of a video proxy cache that integrates modern multimedia and communication standards. Especially we describe features of the MPEG-4 and MPEG-7 multimedia standards that can be helpful for a video proxy cache. QBIX supports real-time adaptation in the compressed and in the decompressed domain. It uses adaptation to improve the cache replacement strategies in the proxy, but also to realize media gateway functionality driven by the clients' terminal capabilities.

Abstract: Web caching is an important technique to scale the Internet. One important performance factor of Web caches is the replacement strategy. Due to specific characteristics of the World Wide Web, there exist a huge number of proposals for cache replacement. This article proposes a classification for these proposals that subsumes prior classifications. Using this classification, different proposals and their advantages and disadvantages are described. Furthermore, the article discusses the importance of cache replacement strategies in modern proxy caches and outlines potential future research topics.

Abstract: In this paper, a generic method is described to allow the adaptation of different multimedia resources by a single, media resource-agnostic processor. This method is based on an XML description of the media resource’s bitstream syntax, which can be transformed to reflect the desired adaptation and then be used to generate an adapted version of the bitstream. Based on this concept, two complementary technologies, BSDL and gBS Schema, are presented. The two technologies provide solutions for parsing a bitstream to generate its XML description, for the generic structuring of this description, and the generation of an adapted bitstream using its transformed description. The two technologies can be used as stand-alone tools; however, a joint approach has been developed in order to harmonise the two solutions and exploit their strengths. Since BSDL has been presented in previous publications, this paper is focusing more on the gBS Schema and the joint BSDL/gBS Schema approach.

Abstract: Multimedia streaming is becoming ever more popular. However, the Internet does not support streaming with its high bandwidth and low latency requirements very well. The problem is that QoS guarantees cannot be given. Hence, communication partners have to deal with rapidly changing connection parameters. This requires sophisticated streaming concepts that can handle these varying conditions using adaptation techniques. Adaptation methods can be dropping layers, dropping access units or transcoding the contents. But this places specific requirements on the underlying protocol. This paper identifies and discusses these requirements and analyzes how existing protocols can meet them. Unfortunately, none of the known protocols can meet all requirements. Hence, we propose a new adaptation-aware multimedia streaming protocol that can operate as required in the given Internet environment. Furthermore, we show how this protocol can be used to carry MPEG-4 audio-visual contents.

Abstract: Multimedia streaming is becoming more and more popular. Seamless video streaming in heterogeneous networks like the Internet turns out as almost impossible due to varying network conditions - streams must be adapted to the current network QoS. Temporal scalability is one of the most reasonable adaptation techniques because it is fast and easy to perform. Today's approaches simply drop frames out of a video without spending much effort on finding an intelligent dropping behavior. This usually leads to good adaptation results in terms of bandwidth consumption but also to suboptimal video quality within the given bounds. Our approach offers analysis of video streams to achieve the qualitatively best temporal scalability. For this reason, we introduce a data structure called modification lattice which represents all frame dropping combinations within a sequence of frames. On the basis of the modification lattice, qualityestimations on frame sequences can be performed. Moreover, a heuristic for fast and efficient quality computation in a modification lattice is presented. Experimental results illustrate that temporal video adaptation based on QCTVA information leads to a better video quality compared to "usual" frame dropping approaches. Furthermore, QCTVA offers frame priority lists for videos. Based on these priorities, numerous adaptation techniques can increase their overall performance when using QCTVA.

Abstract: Euro-Par is the annual series of international conferences dedicated to the promotion and advancement of all aspects of parallel and distributed computing. The conference normally attracts more than 300 participants coming from universities, research centres and industry.

Abstract: Die Moving Picture Experts Group, eine Arbeitsgruppe der ISO SC29, ist seit 1988 aktiv und hat mit ihren MPEG-1/2/4 einen entscheidenden Einfluss auf die Multimedia-Industrie genommen.Mit der Verabschiedung MPEG-7 wurde von der Moving Picture Experts Group (MPEG) im März 2002 als Internationaler Standard verabschiedet. Nach der erfolgreichen Einführung der Standards MPEG-1/2/4 zur audiovisuellen Kodierung von Inhalten ist MPEG-7 ein Standard, der ein Austauschformat für Beschreibungen von multimedialen Inhalten festlegt.

Abstract: Broadly used Database Management Systems (DBMS) are not able to tackle the requirements of multimedia in querying, indexing and content modeling. Therefore, extenders for multimedia data types have been proposed. These extensions, however, offer only limited semantic modeling and rely on basic index structures which do not meet the whole nature of multimedia, for instance for a Nearest-Neighbor Search. In this context, the paper presents a methodology for enhancing extensible ORDBMS for multimedia data. In particular, we introduce an MPEG-7 Multimedia Data Cartridge which includes a semantically rich metadata model for multimedia content relying on the MPEG-7 standard. Furthermore, to fulfill the needs for efficient multimedia query processing, we created in this Cartridge a new indexing and query framework for various types of retrieval operations

Abstract: The ADMITS project (Adaptation in Distributed Multimedia IT Systems) is building an experimental distributed multimedia system for investigations into adaptation, which we consider is an increasingly important tool for multimedia systems. A number of possible adaptation entities (server, proxy, clients, routers) are being explored, different algorithms for media, component and application-level adaptations are being implemented and evaluated, and experimental data are being derived to gain insight into when, where and how to adapt, and how individual, distributed adaptation steps interoperate and interact with each other. In this paper the "adaptation-chain" of (MPEG-conforming) metadata based adaptation is described: from the creation stage at the server side, through its usage in the network (actually in a proxy), up to the consumption at the client. The metadata are used to steer the adaptation processes. MPEG-conformant metadata, the so-called variation descriptions, are introduced; an example of a complete MPEG-7 document describing temporal scaling of an MPEG-4 video is given. The meta-database designed to store the metadata is briefly discussed. We describe how the metadata can be extracted from MPEG-4 visual elementary streams and initial results from the temporal video scaling experiment are given. We further present how the metadata can be utilized by enhanced cache replacement algorithms in a proxy server in order to realize quality-based caching; experimental results using these algorithms are also given. Finally, an adaptive query and presentation interface to the meta-.

Abstract: In memory of Ole-Johan Dahl, Edsger Wybe Dijkstra and Kristen Nygaard. Science is done by people. No matter how trivial this sounds, this is often forgotten, especially in the case of technical sciences such as informatics. In this book we attempt to give a short overview of the life and scientific work of three great computing scientists: Ole-Johan Dahl, Edsger W. Dijkstra and Kristen Nygaard. All three were born around the beginning of the 1930s and died in 2002. All three were among the brightest stars of early informatics (or computing science).

Abstract: The mission of JMLC is to explore the concepts of well-structured programming languages and software, and those of teaching good design and programming style. We are especially interested in the construction of large and distributed software systems. We also invite papers on software engineering aspects in new and dynamic application areas, such as multimedia and pervasive systems.

Abstract: Bei der Indizierung von Videoarchiven haben im allgemeinen bessere Ergebnisse einen höheren Preis. Automatische Indizierung, basierend auf physikalischen Eigenschaften, kann für viele Bereiche (wie z.B. ein Grossteil der Unterhaltung) ausreichend gute Ergebnisse erzielen. Sie ist allerdings in der Genauigkeit der Fragestellungen eingeschränkt, und zwingt uns – oft unbewusste – Suchkriterien auf. Wenn es uns wichtig ist, auf fein differenzierte Fragen genaue Antworten zu erhalten (wie das z.B. in wissenschaftlich/technischen Systemen meistens der Fall ist), so sind wir auf eine zumindest teilweise manuelle Annotierung angewiesen. In einem kombinierten System – wie dem VIDEX-Modell – können die physikalischen Eigenschaften dazu benutzt werden, den manuellen Annotierungsprozess zu erleichtern. Kombinierte Systeme dieser Art bieten beide Arten der Indizierung an und kombinieren sie miteinander. Längerfristig ist zu erwarten, dass sich zu jeder Anwendung die angemessenen Indizierungs- und Suchmethoden herausstellen. Die zwei Verfahren – das automatische und das teils manuelle – sollten nicht als Gegner, sondern als Partner angesehen werden.

Abstract: This paper introduces a mobile agent-based infrastructure for an adaptive multimedia server enabling a dynamic migration or replication of certain multimedia applications among a set of available server nodes. It discusses the requirements from both, the server’s and the middleware’s point of view to each other and comes up with a specification and implementation of a CORBA-based interface between them.