The multimedia multicasting problem

This paper explores the problems associated with the multicasting of continuous media to support multimedia group applications. The interaction between multicasting and the delivery of multiple time-correlated continuous-media streams with real-time delay requirements poses various new and interesting problems in research on communication protocols and architectures. We describe these problems, and identify where the opportunities are for effective solutions, all in the context of providing an overview of the current state of research in multimedia multicasting. The issues we discuss include quality of service, resource reservations, routing, error and traffic control, heterogeneity, and the use of hierarchical coding and open-loop control techniques.     

Interactivity in multimedia learning: An integrated model

What does interactivity entail? What factors need to be taken into account in the design of interactive systems? Although interactivity is a widely used term accorded great prominence in discussions of multimedia learning, even a preliminary look at the literature suggests that how interactivity is defined, and what benefits it may offer, are not at all clear. The goal of this article is therefore to clarify the concept of interactivity. We present a unifying model that includes the user, the learning environment, and a system of connections and concepts that together make up interactivity. Such a model can help inform research, discussion, and design decisions on interactive multimedia instruction.     

An integrated traffic model for multimedia wireless networks

Multimedia wireless networks are seen today as one of the key factors for the success of the global communication infrastructure in the near future. Such networks will have to handle a range of heterogeneous traffic classes with different QoS requirements. Their design, planning and control must be supported by suitable traffic models capable of dealing with a new set of constraints where QoS management and mobility play an important role.This paper proposes a traffic model for a cellular multimedia wireless network characterized by the integration of mobility and traffic management aspects. User mobility is modeled through a Markov renewal process, which allows for non-exponential cell residence times and may restrict the user mobility to existent paths in the system. A Markov-modulated fluid process is used to describe the changes in the bandwidth requirements of each mobile over the duration of its calls, including the periods where the mobile is inactive (without call).Based on the proposed model, the number of mobiles per class of traffic in a cell and the handoff processes are characterized. System performance results, such as new and handoff call blocking probabilities, for network planning are derived. Also, the distribution of the required capacity in a short time interval for network control is obtained. Simulations were carried out to validate the analytical results. The comparisons have shown that the integrated model may be regarded as a good basis to build useful teletraffic engineering tools for multimedia wireless networks.     

A fault tolerant RPC mechanism based on IP multicasting

This paper presents a fault tolerant Remote Procedure Call (RPC) mechanism based on Sun RPC and IP multicast protocol. The fault tolerant RPC mechanism is provided as an RPC library, called libFTRPC, whose interface is compatible with that of conventional Sun's RPC library. Thanks to this compatibility, a reliable RPC server can be developed in the same way a conventional RPC server is constructed. The service reliability is ensured by replicating the server to a group of server replicas. Coordinator-cohort replication model in conjunction with read-one/write-all policy is used to guarantee state consistency between server replicas. We also incorporate a simple and effective approach to balance loads among server replicas to improve performance for read-only requests.     

Design considerations for the symphony integrated multimedia file system

A multimedia file system supports diverse application classes that access data with heterogeneous characteristics. In this paper, we describe our experiences in the design and implementation of the Symphony multimedia file system. We first discuss various methodologies for designing multimedia file systems and examine their trade-offs. We examine the design requirements for such file systems and argue that to efficiently manage the heterogeneity in application requirements and data characteristics, a multimedia file system should enable the coexistence of multiple data-type-specific and application-specific techniques. We describe the architecture and novel features of Symphony and then demonstrate their efficacy through an experimental evaluation. Our results show that Symphony yields a factor of 1.9 improvement in text response time over conventional disk scheduling algorithms while continuing to meet the real-time requirements of video clients. Finally, we reflect upon the lessons learned from the Symphony project.Prashant Shenoy: Correspondence to This research was supported in part by NSF Awards CCR-9624757 and CCR-9984030. Any opinions, findings, conclusions, and recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the funding agencies.     

Future integrated learning environments with multimedia

Abstract  Recent progress in information technology hardware and the spread of the Internet have opened a variety of new ways for many fields. Although slower than the business field to catch up with these new developments, the educational field has gradually migrated towards the World-wide web, mostly under the slogan of free, accessible education, to and from anyplace, at anytime. This development triggered an important shift from the teaching paradigm to the learning paradigm. However, slow network speed hindered the first learning environments from being more than simple, electronic text-books. The latest trends making use of increased bandwidths and integrating various media to enhance learning. Moreover, for obtaining learner-oriented, customised learning environ-ments, intelligent tutoring techniques are being adapted and developed for the web. This paper presents these trends on one hand, but on the other hand, also addresses the dangers and pitfalls that such an avalanche of change can bring and stresses the task of ensuring that the real goal of enhancing and improving learning is not overlooked.     

An integrated runtime QoS-aware middleware framework for distributed multimedia applications

Future-generation distributed multimedia applications are expected to be highly scalable to a wide variety of heterogeneous devices, and highly adaptive across wide-area distributed environments. This demands multiple stages of run-time support in QoS-aware middleware architectures, particularly, probing the performance of QoS parameters, instantiating the initial component configurations, and adapting to on-the-fly variations. However, few of the past experiences in related work have shown comprehensive run-time support in all of the above stages – they often design and build a middleware framework by focusing on only one of the run-time issues. In this paper, we argue that distributed multimedia applications need effective run-time middleware support in all these stages to be highly scalable and adaptive across a wide variety of execution environments. Nevertheless, the design of such a middleware framework should be kept as streamlined and simple as possible, leading to a novel and integrated run-time middleware platform to unify the probing, instantiation and adaptation stages. In addition, for each stage, the framework should enable the interaction of peer middleware components across host boundaries, so that the corresponding middleware function can be performed in a coordinated and coherent fashion. We present the design of such an integrated architecture, with a case study to illustrate how it is simple yet effective to monitor and configure complex multimedia applications.     

A cooperative mechanism for managing multimedia project documentation

Multimedia Tools and Applications - Documentation management is a crucial component of successful business-related projects, but it often involves significant effort in terms of time and cost....     

Adlet: an active document abstraction for multimedia informationfusion

A new approach is described for the fusion of multimedia information based on the concept of active documents advertising on the Internet, whereby the metadata of a document travels in the network to seek out documents of interest to the parent document and, at the same time, advertises its parent document to other interested documents. This abstraction of metadata is called an adlet, which is the core of our approach. Two important features make this approach applicable to multimedia information fusion, information retrieval, data mining, geographic information systems, and medical information systems: 1) any document, including a Web page, database record, video file, audio file, image and even paper documents, can be enhanced by an adlet and become an active document; and 2) any node in a nonactive network can be enhanced by adlet-savvy software and the adlet-enhanced node can coexist with other nonenhanced nodes. An experimental prototype provides a testbed for feasibility studies in a hybrid active network     

Eventor: an authoring system for interactive multimedia applications

Programming, testing, and maintaining interactive multimedia applications (IMAs) are still difficult and expensive, while substantial progress has been made to reduce the burden on authors. As IMAs get larger and more complex the difficulties will increase. To overcome the complexity of such IMAs, we argue that authoring systems should provide such facilities as (1) a traditional and intuitivedivide-and-conquer paradigm for solving large and complex problems in various fields, (2)formal specification of the behaviors of IMAs for checking the syntactic correctness of visual expressions or semantic anomalies, and (3)automatic aids like validation of temporal constraints and verification of visual expressions. In this paper, we investigate the properties of IMAs for recognizing the inherent interactivity and concurrency. We propose a specification method based on Milner'sCalculus of Communicating Systems (CCS), which is a well-known formal mechanism for specifying the concurrency in various distributed applications. We also design and implement an authoring system calledEventor (Event Editor), which is based on CCS and composed of three tools: a Temporal Synchronizer, a Spatial Synchronizer, and a User Interaction Builder. They focus on describing the temporal and spatial synchronizations and user interactions while they rely on existing tools in Intel's Digital Video Interactive (DVI) for supporting other functionalities. By editing a simple computer aided instruction (CAI) application, we illustrate that our specification mechanism is well-suited for handling the interactivity of multimedia applications, and Eventor is a simple, efficient, and powerful enough tool to handle practical applications. Especially the incremental refinement and the formal specification based on the CCS allow Eventor to be extended with formal verifications to cope with large and complex applications.     

PLUS: a probe-loss utilization streaming mechanism for distributed multimedia presentation systems

We present a new flow and congestion control scheme, PLUS (Probe-Loss Utilization Streaming protocol), for distributed multimedia presentation systems. This scheme utilizes probing of the network situation and an effective adjustment mechanism to data loss to support multimedia presentations. The proposed scheme is also designed to scale with increasing number of PLUS-based streaming traffic and to live in harmony with TCP-based traffic. The novelty of the PLUS protocol is that it utilizes the knowledge of its future bottleneck bandwidth in probing the current network situation. This can be achieved by a priori knowledge of the multimedia data before a presentation is requested by a client. Compression schemes like MPEG introduce dependencies on media units. I frames are needed to successfully decode P and B frames, and P frames are needed to decode B frames. A loss of an I or P frame automatically eliminates dependent media units. Our probing scheme increases the successful transmission of critical I and P packets without the overhead of error-correction-schemes. Probing is done using B-frame packets. The advantage is that we use data packets as probe packets. With the PLUS protocol we address the need to avoid congestion rather than react to it. Experiments demonstrate the effectiveness of the approach in utilizing network resources and decreasing loss ratios.     

MING-I: a distributed interactive multimedia document development mechanism

The next generation of interactive multimedia documents can contain both static media, e.g., text, graph, image, and continuous media, e.g., audio and video, and can provide user interactions in distributed environments. However, the temporal information of multimedia documents cannot be described using traditional document structures, e.g., Open Document Architecture (ODA) and Standard Generalized Mark-up Language (SGML); the continuous transmission of media units also raises some new synchronization problems, which have not been met before, for processing user interactions. Thus, developing a distributed interactive multimedia document system should resolve the issues of document model, presentation control architecture, and control scheme. In this paper, we (i) propose a new multimedia document model that contains the logical structure, the layout structure, and the temporal structure to formally describe multimedia documents, and (ii) point out main interaction-based synchronization problems, and propose a control architecture and a token-based control scheme to solve these interaction-based synchronization problems. Based on the proposed document model, control architecture, and control scheme, a distributed interactive multimedia document development mechanism, which is called MING-I, is developed on SUN workstations.     

Dynamic QoS queuing control mechanism for multimedia differentiated services

An essential goal of communication networks is to provide multimedia services with QoS streaming. A properly designed multimedia QoS system must reserve requested resources according to user QoS requirements and the available network resources. However, the static resource allocation among priority queues in DiffServ networks leads to insufficient resource usage when a burst occurs in one priority queue while other queues starve. This study presents a User-Oriented QoS Streaming System to achieve perceptible satisfaction based on novel streaming and media differentiation policies in DiffServ networks. This study also proposes that the Dynamic QoS Queue Mapping (DQ²M) mechanism dynamically control queue scheduling by adaptively maximizing the utilization of queues and network resources according to the soft states of the DiffServ network. Evaluation results indicate that the proposed DQ²M algorithm can improve the fairness and efficiency of resource utilization for low-priority queues.     

Predicting tourism loyalty using an integrated Bayesian network mechanism

For effective Bayesian networks (BN) prediction with prior knowledge, this study proposes an integrated BN mechanism that adopts linear structural relation model (LISREL) to examine the belief or causal relationships which are subsequently used as the BN network structure for predicting tourism loyalty. Four hundred and fifty-two valid samples were collected from tourists with the tour experience of the Toyugi hot spring resort, Taiwan. The proposed mechanism is compared with back-propagation neural networks (BPN) or classification and regression trees (CART) for 10-fold cross-validation. The results indicate that our approach is able to produce effective prediction outcomes.     

Design of integrated multimedia compression and encryption systems

Two approaches for integrating encryption with multimedia compression systems are studied in this research, i.e., selective encryption and modified entropy coders with multiple statistical models. First, we examine the limitations of selective encryption using cryptanalysis, and provide examples that use selective encryption successfully. Two rules to determine whether selective encryption is suitable for a compression system are concluded. Next, we propose another approach that turns entropy coders into encryption ciphers using multiple statistical models. Two specific encryption schemes are obtained by applying this approach to the Huffman coder and the QM coder. It is shown that security is achieved without sacrificing the compression performance and the computational speed. This modified entropy coding methodology can be applied to most modern compressed audio/video such as MPEG audio, MPEG video, and JPEG/JPEG2000 images.     

OMUS: an optimized multimedia service for the home environment

Media content in home environments is often scattered across multiple devices in the home network. As both the available multimedia devices in the home (e.g., smartphones, tablets, laptops, game consoles, etc.) and the available content (video and audio) is increasing, interconnecting desired content with available devices is becoming harder and home users are experiencing difficulties in selecting interesting content for their current context. In this paper, we start with an analysis of the home environment by means of a user study. Information handling problems are identified and requirements for a home information system formulated. To meet these requirements we propose the OMUS home information system which includes an optimized content aggregation framework, a hybrid group-based contextual recommender system, and an overall web-based user interface making both content and recommendations available for all devices across the home network. For the group recommendations we introduced distinct weights for each user and showed that by varying the weights, the coverage (i.e., items that can be returned by the recommender) considerably increases. Also the addition of genre filter functionality was proven to further boost the coverage. The OMUS system was evaluated by means of focus groups and by qualitative and quantitative performance assessment of individual parts of the system. The modularity of internal components and limited imposed hardware requirements implies flexibility as to how the OMUS system can be deployed (ranging from e.g., embedded in hardware devices or more software services based).     

An auto-scaling mechanism for cloud-based multimedia storage systems: a fuzzy-based elastic controller

Multimedia Tools and Applications - Cloud computing is a new technology that is increasing in popularity day-by-day. One of the reasons for its popularity can be its elasticity feature. In other...