Showing papers by "Arif Ghafoor published in 1999"

Semantic modeling and knowledge representation in multimedia databases

Abstract: In this paper, we present the current state of the art in semantic data modeling of multimedia data. Semantic conceptualization can be performed at several levels of information granularity, leading to multilevel indexing and searching mechanisms. Various models at different levels of granularity are compared. At the finest level of granularity, multimedia data can be indexed based on image contents, such as identification of objects and faces. At a coarser level of granularity, indexing of multimedia data can be focused on events and episodes, which are higher level abstractions. In light of the above, we also examine modeling and indexing techniques of multimedia documents.

A multi-level abstraction and modeling in video databases

Abstract: In this paper, we propose a multi-level abstraction mechanism for capturing the spatial and temporal semantics associated with various objects in an input image or in a sequence of video frames. This abstraction can manifest itself effectively in conceptualizing events and views in multimedia data as perceived by individual users. The objective is to provide an efficient mechanism for handling content-based queries, with the minimum amount Of processing performed on raw data during query evaluation. We introduce a multi-level architecture for video data management at different levels of abstraction. The architecture facilitates a multi-level indexing/searching mechanism. At the finest level of granularity, video data can be indexed based on mere appearance of objects and faces. For management of information at higher levels of abstractions, an object-oriented paradigm is proposed which is capable of supporting domain specific views.

Intensive Data Management in Parallel Systems: A Survey

Abstract: In this paper we identify and discuss issues that are relevant to the design and usage of databases handling massive amounts of data in parallel environments. The issues that are tackled include the placement of the data in the memory, file systems, concurrent access to data, effects on query processing, and the implications of specific machine architectures. Since not all parameters are tractable in rigorous analysis, results of performance and bench-marking studies are highlighted for several systems.

Trail-based approach for video data indexing and retrieval

Abstract: Increasing use of multimedia data makes it crucial to use intelligent search mechanisms for retrieving multimedia data by content. Digital video requires the incorporation of temporal information for any effective content-based retrieval scheme. We present a trail-based model which uses the object motion information in order to characterize the events for subsequent searches for "similar" clips. Algorithms for different spatio-temporal search modes using various digital signal processing techniques are also introduced. We implemented the proposed methods and demonstrated that high-level query formulation can be achieved for the aforementioned purpose.

An approach for video meta-data modeling and query processing

Abstract: Multimedia databases have been the subject of extensive research for the last several years. In particular, semantic modeling of video data spurred tremendous interest and produced various formalisms for content-based retrieval of video data. In this paper, we propose the use of Hierarchical Petri-nets (HPN's) for multi-level representation of video data with each level consisting of an augmented Petrinet structure. We show how such representation is able to capture video data semantics, from very low level semantics such as scene change and object movements to higher level semantics involving high-level textual description of events. A Petri-net based method for query processing of multi-object spatio-temporal video-data queries is presented.

Network modeling and jitter control for multimedia communication over broadband network

Abstract: For pre-orchestrated multimedia documents, the important QoS parameters are bandwidth, jitter and reliability. A data network may employ a large number of service disciplines that provide guaranteed QoS. In this paper, we propose a network model, which we call the jitter graph, to capture the bandwidth, jitter and reliability of a large number of service disciplines. The significance of this model is that it abstracts the properties of the network, which allows the design of QoS routing protocols, resource allocation policies, and traffic regulation schemes that are independent of the specific properties of each node. Based on this model, we propose a traffic regulation scheme that reduces, and possibly eliminates, jitter introduced by any service discipline that can be abstracted by the jitter graph network model. The proposed traffic regulation scheme, together with jitter graph model, are analyzed and simulated based on an existing service discipline.

Indexing and retrieval of video based on spatial relation sequences

Abstract: An important aspect of video data is its spatio-temporal aemantics. The relative positions and movements of the “interesting” objects in a video segment constitute a crucial component of the information to be retrieved in a multimedia database system. This is due to the dependency of the complex content descriptions on the apatio-temporal features. This paper addresses this challenge and provides an efficient technique for video data retrieval using descriptions of relative object movements. Such descriptions are used for content-baaed retrieval processing baaed on a graphical representation, named Coordinate Valued Neighborhood Graph.

Design and evaluation of disk scheduling policies for high-demand multimedia servers

Abstract: We propose and evaluate techniques to manage disk storage systems for multimedia document servers with constrained I/O resources. We also evaluate the requirements for the main memory to maintain desired levels of quality of presentation (QoP) for multiple users. This is achieved by attempting to minimize the number of tardy frames in end-to-end delivery of multimedia data. Inter-media and intra-media temporal synchronization at the user-interaction level are essential concerns for multimedia servers. Scheduling of multimedia frames has direct impact on both intra-stream and inter-stream multimedia synchronization. In order to effect such synchronization, we propose several O(n log n+mn) heuristics to schedule multimedia frames between the disks and destination memories of the multimedia systems, where m is the number of logical I/O channels and n is the number of frames of multimedia data. We study the performance of these heuristics via simulations and show the tradeoffs between the system resources and QoP parameters.

Dynamic Resource Allocation for Multimedia Document Retrieval over High Speed LANs

Abstract: The emergence of gigabit local area networks (G-LANs) has spurred a tremendous interest in supporting networked multimedia applications over a LAN. In this paper, we propose a mechanism for dynamically allocating network resources in asynchronous LANs. Presentation of multimedia objects with required play-out quality requires Quality of Service (QoS) guarantees by the underlying networking infrastructure. Existing asynchronous LANs, such as Ethernet, do not support the notion of QoS due to their asynchronous media access protocol. For such networks, we propose a dynamic bandwidth management scheme that uses the concept of Time Division Multiple Access (TDMA). Significant performance improvement is observed through experimental results. In particular, the transmission rates for multimedia hosts improve significantly with low jitter variations in media streams. We also propose a framework for graceful degradation of play-out quality of multimedia objects in case the LAN‘s total capacity is not sufficient to meet the overall demand.

Media Streams Scheduling for Synchronization in Distributed Multimedia Systems

Abstract: In this paper, we consider the problem of multimedia synchronization based on scheduling the transmission of multimedia documents in a networked environment. Assuming channels with different bandwidth and delay characteristics are established between the multimedia server and the client, we formulate the scheduling problem to ensure interstream and intrastream synchronization as a parallel processor scheduling problem. Since the heterogeneous parallel processor scheduling problem is NP-hard, we propose two heuristic algorithms with time complexity ofO(nlogn+nm), wherenis the number of data units to be scheduled andmthe number of channels available. We also develop an enumerative algorithm to obtain the exact solutions. Extensive computational simulations reveal that the heuristics consistently obtain near-optimal solutions. From the simulation results, we also identify special structures of multimedia documents along with characteristics of the available channels which affect the relative performance of the algorithms.

A protocol architecture for guaranteed quality of service in collaborated multimedia applications

Abstract: The role of multimedia applications in our day-to-day life has dramatically increased in the last few years. In this paper, we present an architectural framework for the distributed multimedia systems. The architecture consists of three layers: the application layer, the configuration and synchronization layer, and the network layer. The three layers are backed up by two backbone layers, namely, the database and the computational backbone. We present a precise description of each layer together with formal specifications using finite state automata.

Quality of service routing and traffic regulation for distributed multimedia systems

Abstract: In this research, we focus on three main challenges in multimedia networks: network modeling, traffic smoothing, and QoS routing with resource allocation. We start by proposing a low-level network model called the jitter graph model, which captures the dynamic QoS characteristics of a data network while preserving the topological information necessary for routing. The proposed model captures the QoS characteristics as functions or regions, rather than static numerical values and incorporates the interrelationships between the different QoS parameters and the allocated resources. The second research task is to design a lossless, light-weight, flexible, service-discipline-independent traffic reshaping regulator, which we call the Initial Delay Regulator (IDR). The objective of the IDR is to smooth out the burstiness of the traffic inside the network without relying on per-packet tagging. The third research task is to address the problems of QoS routing and resource allocation. The jitter graph model allows combining the problems of QoS routing and resource allocation in a single framework. We start by re-defining the problem of resource allocation on a given path. The objective is to satisfy the QoS requirement along this path. Then we define the problem of QoS routing with resource allocation. The new definition incorporates QoS routing and resource allocation in the same framework and allows trading off different QoS parameters. We propose a dynamic programming algorithm that, under certain conditions, finds a network route between a source and destination nodes and decides the amount of resources needed along the path so that the QoS requirements are satisfied. After proving the correctness of the proposed algorithm, we present a worst-case analysis of jitter and droppage under insufficient resources conditions for some of the well known service disciplines. The analysis provides deterministic relations between the QoS parameters and the resources for networks that employ these service disciplines. Having this analysis, we apply the formulation of the problem of QoS routing with resource allocation and the proposed algorithm dynamic programming algorithm to networks that employ these service disciplines to solve the problem of QoS routing with resource allocation in polynomial time.

Multimedia Information Systems

Abstract: The sections in this article are 1 Requirements of Multimedia Information Systems 2 Notion of Time for Multimedia Data 3 Content-Based Retrieval of Multimedia Data 4 Multimedia Document Modeling and Retrieval 5 Conclusion

A scalable call admission control algorithm for ATM networks

Abstract: In this paper we propose a computationally efficient and scalable algorithm for connection admission control (CAC) for an ATM switch with a FIFO buffer. The sources may be heterogeneous both in terms of their statistical characteristics as well as their quality of service (QoS) requirements. The performance of the proposed CAC scheme is evaluated against various CAC algorithms proposed in the literature and using simulation results. Our results show that the proposed CAC consistently performs better and operates the link close to the highest possible utilization level.