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1.
An approach to the document-retrieval problem that aims to increase the efficiency and effectiveness of document-retrieval systems by exploiting the semantic contents of the documents is presented. The document retrieval problem is delineated, and conceptual document modeling basics and requirements are discussed. An experimental system, the Multimedia Office Server (Multos), which implements some of the document-model concepts described, is presented 相似文献
2.
This paper presents TAO: a language based on Temporal Algebraic Operators for composing complex multimedia presentations. Unlike traditional approaches used to specify multimedia presentations, TAO relies on a well-defined semantics with an underlying temporal model based on intervals and causal relations between time points. We derive some properties of TAO presentations and show how to execute TAO presentations on an execution engine: a TAO presentation is compiled into a set of instructions interpreted by the execution engine. 相似文献
3.
This study investigates sequence optimization of media objects in a multimedia presentation that is dynamically composed from digital libraries. Each media object can be associated with a due date. The aim is to schedule the media objects in a delay-prone network environment such that the overall presentation lag and the due date penalties of the media objects of presentations can be minimized. We formulate the sequencing problem with buffer constraints in the media player into a flowshop scheduling problem and present a reduction strategy with a branch and bound algorithm to derive optimal sequences. The algorithm can be applied in applications with up to a dozen objects to be scheduled. In addition, we propose a modified NEH-based heuristic algorithm which can provide approximate solutions with an average error rate of less than 4%. The computation-efficient heuristic, when deployed in applications with heavily loaded servers, can obtain near-optimal sequences for problems with more than a dozen objects. The proposed algorithms are embedded into a prototype system for providing digital library services. 相似文献
4.
The bandwidth limitations of multimedia systems force trade-offs between presentation-data fidelity and real-time performance.
For example, digital video is commonly encoded with lossy compression to reduce bandwidth, and frames may be skipped during
playback to maintain synchronization. These trade-offs depend on device performance and physical data representations that
are hidden by a database system. If a multimedia database is to support digital video and other continuous media data types,
we argue that the database should provide a quality-of-service (QOS) interface to allow application control of presentation
timing and information-loss trade-offs. This paper proposes a data model for continuous media that preserves device and physical
data independence. We show how to define formal QOS constraints from a specification of ideal presentation outputs. Our definition
enables meaningful requests for endto-end service guarantees, while leaving the database system free to optimize resource
management. We propose one set of QOS parameters that constitute a complete model for presentation error, and we show how
this error model extends the opportunities for resource optimization. 相似文献
5.
The single-system approach is no longer sufficient to handle the load on popular Internet servers, especially for those offering
extensive multimedia content. Such services have to be replicated to enhance their availability, performance, and reliability.
In a highly replicated and available environment, server selection is an important issue. In this paper, we propose an application-layer
broker (ALB) for this purpose. ALB employs a content-based, client-centric approach to negotiate with the servers and to identify
the best server for the requested objects. ALB aims to maximize client buffer utilization in order to efficiently handle dynamic user
interactions such as skip, reverse presentation, go back in time. We also present details of a collaborative multimedia presentation
platform that we have developed based on ALB. 相似文献
6.
Conceptual modeling of a subject domain, which produces its conceptual model, is an important stage in designing information
systems. In recent years, much attention in the development of such systems has been given to reusing information resources
and to providing access to them at the semantic level. Methods and technologies of ontological modeling have lately been under
intensive development. In this paper, problems and preconditions of conceptual modeling of the subject domain in database
technologies and information systems are discussed. Various approaches to conceptual modeling, conceptual modeling languages,
and the respective tools are considered, various interpretations of the role of the conceptual model of the subject domain
are discussed, and the current state of conceptual modeling tools produced by software industry is assessed. The relationships
between the conceptual schemas of the subject domain and ontologies are analyzed and their similarities and differences are
described. Terminological issues and the directions of research in the field of conceptual and ontological modeling are considered.
An extensive list of references is given. 相似文献
7.
In this paper we discuss issues concerning the consistent retrieval of parts of multimedia presentations from multimedia repositories. We introduce a class of multimedia presentations made of independent and synchronized media and discuss retrieval requirements of presentation fragments. Then we discuss a retrieval model capable of reconstructing the fragments of a presentation from the atomic components returned by the execution of queries to multimedia presentation repositories. The retrieval model is based on an automaton that formally describes the presentation states entered by the events that trigger media playback. Retrieving a consistent fragment corresponds to building a new presentation with all the media related to the retrieved ones, with their original structural and synchronization relationships. 相似文献
9.
A key requirement to today's fast changing economic environment is the ability of organizations to adapt dynamically in an effective and efficient manner. Information and Communication Technologies play a crucially important role in addressing such adaptation requirements. The notion of `intelligent software' has emerged as a means by which enterprises can respond to changes in a reactive manner but also to explore, in a pro-active manner, possibilities for new business models. The development of such software systems demands analysis, design and implementation paradigms that recognize the need for `co-development' of these systems with enterprise goals, processes and capabilities. The work presented in this paper is motivated by this need and to this end it proposes a paradigm that recognizes co-development as a knowledge-based activity. The proposed solution is based on a multi-perspective modeling approach that involves (i) modeling key aspects of the enterprise, (ii) reasoning about design choices and (iii) supporting strategic decision-making through simulations. The utility of the approach is demonstrated though a case study in the field of marketing for a start-up company. 相似文献
10.
We propose in this paper a context-aware adaptation technique for SMIL encoded multimedia documents. Our approach is mainly
dedicated to run in compile-time but we discuss also how it can be used in runtime. Our algorithm aims at improving the execution
of a multimedia presentation. This is achieved by scheduling object pre-fetchings in the presentation while monitoring bandwidth
and memory space availabilities. For this effect, a request pattern computed from the temporal graph of the SMIL specification
is exploited in order to apply an optimal policy to select which objects should be pre-fetched, real time delivered or discarded,
even. The algorithm can be used as a tool to evaluate and to monitor the QoS of a presentation. At compile time, it makes
it possible to assess whether the QoS of a presentation can be guaranteed after enforcing specific context-oriented adaptations.
At authoring stage, this algorithm can be used, for instance, to produce different alternative sub-codes, such that each one
is adapted to run in a specific context. In runtime, the algorithm can provide a mechanism to monitor the elastic time computation
in case of a mismatch occurrence. In order to advocate our proposal, some experimentation results performed on a simulation
platform are reported. 相似文献
12.
Most multimedia servers reported in the literature are designed to serve multiple and independent video/audio streams. We
think that, in future, multimedia servers will also serve complete presentations. Multimedia presentations provide unique
opportunities to develop algorithms for buffer management and admission control, as execution-time consumption requirements
of presentations are known a priori. In this paper, we examine presentations in three different domains (heavyweight, middleweight,
and lightweight) and provide buffer management and admission control algorithms for the three domains. We propose two improvements
(flattening and dynamic-adjustments) on the schedules created for the heavyweight presentations. Results from a simulation
environment are presented.
Received June 9, 1998 / Accepted October 13, 1998 相似文献
13.
The presentation of multimedia data is not only characterized by precise temporal constraints; also spatial constraints must be taken into account. An important requirement in multimedia systems is thus the integrated modeling of spatio-temporal constraints. Moreover, it is important to devise methods for checking the consistency of the specified constraints. In this paper, we first propose a spatio-temporal object graph (STOG) model that provides an integrated and graphical representation of spatio-temporal constraints. Second, we investigate consistency conditions between spatial and temporal constraints expressed in the STOG model. Then, we present a prototype system implementing the proposed model. 相似文献
14.
Over the last few years, there has been a tremendous increase in the number of interactive multimedia presentations prepared
by different individuals and organizations. In this paper, we present an algebra for creating and querying interactive multimedia
presentation databases. This algebra operates on trees whose branches reflect different possible playouts of a set of presentations.
The algebra not only extends all the classical relational operators to such databases, but also introduces a variety of novel
operators for combining multiple presentations. As our algebra supports merging parts or all of existing presentations, this
algebra can also be used as an authoring tool for creating multimedia presentations. We prove a host of equivalence results
for queries in this algebra, which may be used to build query optimizers for interactive presentation databases. 相似文献
15.
Considers the problem of querying multimedia presentations based on content information. Multimedia presentations are modeled as presentation graphs, which are directed acyclic graphs that visually specify the presentations. We present a graph data model for the specification of multimedia presentations and discuss query languages as effective tools to query and manipulate multimedia presentation graphs with respect to content information. To query the information flow throughout a multimedia presentation, as well as in each individual multimedia stream, we use revised versions of temporal operators Next, Connected and Until, together with path formulas. These constructs allow us to specify and query paths along a presentation graph. We present an icon-based graphical query language, GVISUAL, that provides iconic representations for these constructs and a user-friendly graphical interface for query specification. We also present an OQL-like language, GOQL (Graph OQL), with similar constructs, that allows textual and more traditional specifications of graph queries. Finally, we introduce GCalculus (Graph Calculus), a calculus-based language that establishes the formal grounds for the use of temporal operators in path formulas and for querying presentation graphs with respect to content information. We also discuss GCalculus/S (GCalculus with Sets) which avoids highly complex query expressions by eliminating the universal path quantifier, the negation operator and the universal quantifier. GCalculus/S represents the formal basis for GVISUAL, i.e. GVISUAL uses the constructs of GCalculus/S directly 相似文献
16.
Authoring of multimedia content can be considered as composing media assets such as images, videos, text, and audio in time,
space, and interaction into a coherent multimedia presentation. Personalization of such content means that it reflects the
users’ or user groups’ profile information and context information. Enriching the multimedia content with semantically rich
metadata allows for a better search and retrieval of the content. To actually create personalized semantically-rich multimedia
content, a manual authoring of the many different documents for all the different users’ and user groups’ needs is not feasible.
Rather a (semi-)automatic authoring of the content seems reasonable. We have analyzed in detail today’s approaches and systems
for authoring, personalizing, and semantically enriching multimedia presentations. Based on this analysis, we derived a general
creation chain for the (semi-)automatic generation of such content. In this paper, we introduce this creation chain. We present
our software engineering support for the chain, the component framework SemanticMM4U. The canonical processes supported by
the creation chain and SemanticMM4U framework are described in detail. We also provide an explicit mapping of SemanticMM4U
framework components to the processes and argue for the benefits of defining canonical processes for creating personalized
semantically rich multimedia presentations. 相似文献
17.
With increases in the complexity and dynamics of multimedia information communicated by current applications, there arises a corresponding need towards a standard technology for intelligent multimedia interfaces. In this article, we address those components of an intelligent multimedia presentation system (IMMPS) which deal with the design and the realization of spatial layout. We treat multimedia layout as a multidimensional constraint problem and propose a reference architecture for a general-purpose intelligent multimedia layout manager (IMMLM) that is based on a dedicated constraint solver kernel. 相似文献
18.
This paper describes work undertaken as part of a three-stranded project. The main deliverable will be a suite of software tools, classes and components, as well as teaching resources and methodologies to facilitate the production of intelligent multimedia tutoring systems. The three strands of this project explore differing aspects of multimedia, and while they stand as separate pieces of work in their own right, they also form the building blocks of the final deliverable, which is an intelligent tutoring system. Intermediate outcomes include a multimedia shell and the Manley Group Demonstrator. This paper focuses on the design and development of the “true multimedia” demonstrator that has now reached the stage of being a fairly mature prototype. It is used commercially by a communications company to illustrate the varying levels of sophistication which can be achieved in presentation systems and provides an exemplar demonstrating the varying degrees of functionality possible using current technology. The main requirement in the design and implementation has been usability both for end users and content developers. Real-time control of the multimedia devices is achieved using sophisticated software which is tightly integrated with dedicated control hardware. The software can be used to produce canned presentations or highly interactive systems. The system is installed in a dedicated presentation suite, thus allowing the true nature of multimedia to be demonstrated. It is scaleable in that it can be used to produce stand-alone portable solutions, highly interactive touch-screen controlled applications or complete multi-device high end presentations. This is achieved using the appropriate combination of software tools and hardware for a specific application. Macromedia Director is used to produce visual and creative material for the system, while Macromedia Authorware can be used to provide interactivity. © 1997 Elsevier Science B.V. 相似文献
19.
An educational digital library is a specialized digital library containing instructional materials, such as class lectures,
seminar presentations, and various training materials. These materials consist of a combination of audio, video, and image
data. In such an environment, basic parts of multimedia data are usually stored in databases and sophisticated multimedia
presentations may be assembled to generate various presentations. In this paper, we investigate a theory of the scheduling
strategies for supporting the synchronized presentations of multimedia streams which is applicable to educational digital
libraries. This scheduling theory includes the specification and representation of synchronization on media streams, the realization
of appropriate synchronization granularity, and the scheduling principles for the presentations of multimedia streams. This
investigation formulates criteria for specifying and scheduling the skipping/pausing of media streams with asynchronous presentations
when various delays occur. Adaptability to various quality-of-service requirements is supported in the scheduling strategies.
Various synchronization mechanisms at both client and server sides are proposed to implement the scheduling theory. Experimental
analysis is conducted using instructional materials. 相似文献
20.
One of the challenges in the design of a distributed multimedia system
is devising suitable specification models for various schemas in
different levels of the system.
Another important research issue is
the integration and synchronization of heterogeneous multimedia
objects. In this paper, we present our models for multimedia schemas
and transformation algorithms. They transform high-level
multimedia objects into schemas that can be used to
support the presentation and communication of the multimedia objects.
A key module in the system is the Object Exchange Manager (OEM). In this paper,
we present the design and implementation of the OEM module,
and discuss in detail the interaction
between the OEM and other modules in a
distributed multimedia system. 相似文献
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