6437408
Application-specific file prefetching for multimedia programs
This paper describes the design, implementation, and evaluation of an automatic application-specific file prefetching mechanism that is designed to improve the I/O performance of multimedia programs with complicated access patterns. The key idea of the proposed approach is to convert an application into two threads: a computation thread, which is the original program containing both computation and disk I/O, and a prefetch thread, which contains all the instructions in the original program that are related to disk accesses. At run time, the prefetch thread is scheduled to run far ahead of the computation thread, so that disk blocks can be prefetched and put in the file system buffer cache before the computation thread needs them. A source-to-source translator is developed to automatically generate the prefetch and computation thread from a given application program without any user intervention. We have successfully implemented a prototype of this automatic application-specific file prefetching mechanism under Linux. The prototype is shown to provide as much as 54% overall performance improvement for real-world multimedia applications.
5738405
Zodiac: A history-based interactive video authoring system
Abstract. Easy-to-use audio/video authoring tools play a crucial role in moving multimedia software from research curiosity to mainstream applications. However, research in multimedia authoring systems has rarely been documented in the literature. This paper describes the design and implementation of an interactive video authoring system called Zodiac, which employs an innovative edit history abstraction to support several unique editing features not found in existing commercial and research video editing systems. Zodiac provides users a conceptually clean and semantically powerful branching history model of edit operations to organize the authoring process, and to navigate among versions of authored documents. In addition, by analyzing the edit history, Zodiac is able to reliably detect a composed video stream's shot and scene boundaries, which facilitates interactive video browsing. Zodiac also features a video object annotation capability that allows users to associate annotations to moving objects in a video sequence. The annotations themselves could be text, image, audio, or video. Zodiac is built on top of MMFS, a file system specifically designed for interactive multimedia development environments, and implements an internal buffer manager that supports transparent lossless compression/decompression. Shot/scene detection, video object annotation, and buffer management all exploit the edit history information for performance optimization.
6822991
An Integrated Pipeline of Decompression, Simplification and Rendering for Irregular Volume Data
Very large irregular-grid volume data sets are typically represented as tetrahedral mesh and require substantial disk I/O and rendering computation. One effective way to reduce this demanding resource requirement is compression. Previous research showed how rendering and decompression of a losslessly compressed irregular-grid data set can be integrated into a one-pass computation. This work advances the state of the art one step further by showing that a losslessly compressed irregular volume data set can be simplified while it is being decompressed and that simplification, decompression, and rendering can again be integrated into a pipeline that requires only a single pass through the data sets. Since simplification is a form of lossy compression, the on-the-fly volume simplification algorithm provides a powerful mechanism to dynamically create versions of a tetrahedral mesh at multiple resolution levels directly from its losslessly compressed representation, which also corresponds to the finest resolution level. In particular, an irregular-grid volume renderer can exploit this multi-resolution representation to maintain interactivity on a given hardware/software platform by automatically adjusting the amount of rendering computation that could be afforded, or performing so called time-critical rendering. The proposed tetrahedral mesh simplification algorithm and its integration with volume decompression and rendering has been successfully implemented in the Gatun system. Performance measurements on the Gatun prototype show that simplification only adds less than 5% of performance overhead on an average and with multi-resolution pre-simplification the end-to-end rendering delay indeed decreases in an approximately linear fashion with respect to the simplification ratio.
35542914
A Decoupled Architecture for Application-Specific File Prefetching
8861403
Design and implementation of the just-in-time retrieving policy for schedule-based distributed multimedia presentations
In order to provide the smooth playback of a distributed multimedia presentation, the object-retrieving engine for the player must fetch each object before its playback time. In this paper, a smart object-retrieving engine is proposed, which adopts a retrieving policy named the just-in-time policy. The policy expects the retrieval process of an object to finish right before the playback time of the object to achieve a better buffer utilization and network bandwidth efficiency. The proposed object-retrieving engine focuses on SMIL1.0-based multimedia presentations. By converting the synchronization relationship of objects in the SMIL 1.0 document to Real-Time Synchronization Model, which simplifies the handling of the synchronization relationship, and considering the end-to-end bandwidth as well as the user interactions, the object-retrieving engine determines the object request time for each object. The engine issues the request to fetch each object for the ongoing presentation at the object request time, and provides the player with proper media objects. The feasibility and better performance of the proposed just-in-time retrieving policy had been proved by performance measurements of system implementation.
6374629
A Multimedia Synchronization Model and Its Implementation in Transport Protocols
An implementation of a synchronization mechanism in transport protocol to support multimedia applications over a packet or cell switched network is proposed. In designing such a mechanism for practical use, ease of implementation and capability of handling random delay of packets are two key issues for success. Since the random delay of packet or cell switched networks makes synchronization among media more complicated after the transmission across the network, a model which considers the random transmission delay is hence required to specify the temporal relationship among media. Therefore, a real-time synchronization model is presented to satisfy this requirement in the paper. Based on the proposed synchronization model, a transport protocol, namely the multimedia synchronization transport protocol (MSTP), is designed and implemented. We have implemented a prototype system using the MSTP protocol and built a simulation system for the wide area network (WAN) environment in order to evaluate the performance of the MSTP protocol.
15408418
CatRelate: A New Hierarchical Document Category Integration Algorithm by Learning Category Relationships
We address the problem of integrating documents from a source catalog into a master catalog. Current technologies for solving the problem deem it as a flat category integration problem without considering the useful hierarchy information in the catalog, or deal with it hierarchically but without a rigorous model. In contrast, our method is based on correctly identifying relationships among categories, such as Match, Disjoint, SubConcept, SuperConcept, and Overlap, which come from the relations of sets in Set theory. Compared with traditional Match/NotMatch relationship in literature, our approach is more expressive in defining the relationship. The relationships among categories are first learned in a probabilistic way, and then refined by considering the hierarchy context. Our preliminary experiments show that it can help to correctly identify category relationships, and thus increase the accuracy of document integration.
5072535
A Workflow-based Computational Resource Broker with Information Monitoring in Grids
As grid computing becomes a reality, a resource broker is needed to manage and monitor available resources. This work presents a workflow-based computational resource broker whose main function is to match available resources with user requests and consider network information status during matchmaking. The resource broker provides a uniform interface for accessing available and the appropriate resources via user credentials. We utilize the NWS tool to monitor the network-related information and resources status. Also, we constructed a grid platform using Globus Toolkit that integrates the distributed resources of five universities in Taichung, Taiwan, where the resource broker is developed. As a result, the proposed broker provides secure and updated information about available resources and serves as a link to the diverse systems available in the grid
350148
Visualization tools for self-organizing maps
Various statistical and pattern recognition techniques, such as concept spaces and category maps in the Illinois Digital Library project, has been explored to solve the semantic interoperability problem in DLI-1. Self-organizing category map is identified as a powerful tool for information summarization. However, visualizing a large-scale self-organizing map in a restricted size of window is difficult. For smaller regions, displaying labels is infeasible. In this paper, two visualization tools, fisheye view and fractal view, are presented. It assists users to visualize a largescale self-organizing map geographically and semantically.