. A novel database system service called playout management service which performs multimedia presentations was proposed recently. In distributed multimedia database systems without end-to-end guarantees, such a playout management service faces the potential problem that system performance can become insufficient when realizing a stored presentation. This problem can be overcome by making the playout management service reactive such that it balances the data amount to be fetched from a remote multimedia database with the system performance available. For the users this means that, a running presentation is adapted by the playout management service. In this paper, we propose the concept of #-set to adapt the execution of arbitrary multimedia presentations in an optimized way. We show a heuristic scheme to identify the most adequate #-set with respect to (1) the actual system state, (2) the user preferences, and (3) the specific properties of multimedia presentations. 1 Introduction ...

Database systems which support preorchestrated multimedia presentations mustbeabletoadaptthe resource demand of executing presentations. Such adaptations can be dictated by underlying resource management components. When resources are not reserved, such adaptations are necessary to overcome fluctuating resource availability. Adaptations across components of presentations as well as across concurrent sessions have to be considered in the context of the individual needs of presentation providers and viewers. This paper describes the general concept of Reactive Playout Management (RPM) which provides an application-independent service for adaptivemultimedia presentations. The PYLOT scheme (PlaYout Load OpTimization scheme) is proposed which enables RPM in best-effort architectures. In particular, the global allocation routine of PYLOT is elaborated. This routine allocates load shares which sessions must giveupormay add on according to replugable adjustment strategies. In an optio...

The paper describes recent progress in research on database system support for executing multimedia presentations. It proposes the general concept of Reactive Playout Management to adjust multimedia presentations. This adjustment can be required due to performance fluctuations as in the absence of end-to-end quality of service guarantees, cost constraints specified by the user, and other reasons. A concrete concept to realize Performance-Based Reactive Playout Management in distributed Multimedia Database Systems is proposed. This covers the identification of respective components in distributed database system architectures along with corresponding algorithms. 1.

In a distributed multimedia database presentation, transactions (playout agents) for the multimedia database system need to cooperate with each other to handle online user interactions or to manage the presentation dynamically over a network. We propose a model for such transactions to cooperate through rules and task communication and synchronization. Transaction cooperation can be specified both statically at transaction-compile time and/or dynamically at execution time. We propose a model where Event-Condition-Action (ECA) rules and non-ECA rules can be specified and triggered. Also, an action can be performed or prohibited in a given time interval. 1 Introduction Transactions in some database applications not only compete, but also cooperate for exchanging information, synchronizing activities, and sharing resources, and for achieving maximum system performance [Lin 89]. It is proposed in the literature [Gray 81, RS 91, Singhal 88] that the ACIDity (Atomicity, Consistency, Isolati...

We introduce a constraint-driven methodology for the automated assembly, organization and playout of presentations from multimedia databases. We use inclusion and exclusion constraints for extracting a semantically coherent set of multimedia segments. Presentation organization constraints are utilized for organizing the multimedia segments into a presentation, which in turn helps decide the playout order of the extracted multimedia segments. The playout order of the segments is represented in a presentation graph. If the specified set of organization constraints are not sufficient to construct a unique presentation graph, we propose two techniques so that a unique graph is constructible. We also propose two playout algorithms, one for the generation, start and termination of playout agents, the other for dynamic control of playout management on organized presentations. The characteristics of these algorithms are expressed in terms of presentation playout parameters.

In this paper, we develop a new service to support optimally ensured user interactions with minimum latency in interactive distributed multimedia presentation environments. The novelty of our scheme is to reduce bandwidth requirements of a network in exchange of memory at the client side, because we expect an increase in network load in the next years in comparison to falling memory prices. Utilizing the properties of smoothing algorithms presented in the literature, we introduce the concepts of the interactive river bed and optimal interactive river bed, which guarantee optimal interactive service over the whole playback time of the video stream. Our approach provides optimal service for a given buffer size. We also derive requirements for a minimal buffer size in which we can give the optimal boundaries for an interactive transmission plan. Experiments demonstrate the effectiveness of the approach. 1 Introduction Multimedia presentations can be constructed from various databases (o...

HUANG-CHENG KUO This thesis proposes a model for database transactions to cooperate through rules, task communication and synchronization. Database transactions manipulate persistent and transient data objects. With event-conditionaction (ECA) rules from active databases, the model provides transactions with a new way of cooperation. Task communication and synchronization can be specified not only statically inside transactions, but also dynamically through rules. Statically specified task communication and synchronization cannot handle dynamic changes, which provides the motivation for using rules. A transaction manager is involved in transaction cooperation by invoking transaction manipulation operations, e.g., start a transaction as a result of an event.

Distributed multimedia presentation systems require high flexibility and good quality of service. To ensure flexible and satisfiable presentations of multimedia data, collaborations between servers, network, and clients must be carefully designed to retrieve the data from the disk and transfer the data to the client. In addition the system must be able to handle interactive requests with minimal latency. However, most of current multimedia data is provided in a compressed form to reduce storage requirements. Data compression techniques introduce burstiness in multimedia data, which complicates buffer and resource management. Current designs lack a uniform transmission support necessary for multimedia presentation systems, which utilize compressed data. In this proposal, we introduce an efficient transmission framework for the NetMedia system. NetMedia is a future novel distributed presentation system, which includes data base management, admission control and graphical inter...

In this paper, we describe a similarity-based retrieval framework for temporal information, such as multimedia presentations. We develop techniques that allow users to query and retrieve multimedia documents, based on their temporal content. For this purpose, we describe different temporal data models and a set of similarity metrics applicable for different retrieval tasks. We develop algorithms that efficiently compute these metrics and report on experiment results. We also develop algorithms that efficiently index temporal structures based on these measures and show that the proposed variant of multi dimensional scaling is efficient and provides high quality retrieval of temporal specifications.