Thomas D. C. Little

Synchronization and storage models for multimedia objects

A technique is presented for the formal specification and modeling of multimedia composition with respect to intermedia timing. The proposed model is based on the logic of temporal intervals and timed Petri nets. A strategy is evinced for constructing a database schema to facilitate data storage and retrieval of media elements based on the temporal relationship established by the proposed modeling tool. An algorithm which allows the retrieval of media elements from the constructed database in a manner which preserves the temporal requirements of the initial specification is presented. Using the proposed model, the synchronization requirements of complex structures of temporally related objects can be easily specified. >

Prospects for Interactive Video-on-Demand

Interactive multimedia systems are rapidly evolving from marketing hype and research prototypes to commercial deployments.We survey the technological issues for designing a large-scale, distributed, interactive multimedia system.

Interval-based conceptual models for time-dependent multimedia data

Multimedia data often have time dependencies that must be satisfied at presentation time. To support a general-purpose multimedia information system, these timing relationships must be managed to provide utility to both the data presentation system and the multimedia author. New conceptual models for capturing these timing relationships, and managing them as part of a database are proposed. Specifically, n-ary and reverse temporal relations are introduced and defined along with their temporal constraints. These new relations are a generalization of earlier temporal models and establish the basis for conceptual database structures and temporal access control algorithms to facilitate forward, reverse, and partial-interval evaluation during multimedia object playout. The proposed relations are defined to ensure a property of monotonically increasing playout deadlines to facilitate both real-time deadline-driven playout scheduling or optimistic interval-based process playout. A translation of the conceptual models to a structure suitable for a relational database is presented. >

Multimedia synchronization protocols for broadband integrated services

Protocols to provide synchronization of data elements with arbitrary temporal relationships of both stream and non-stream broadband traffic types are proposed. It is specified that the provision of a synchronization function be performed within a packet switched network, and, accordingly, a two-level communication architecture is presented. The lower level, called the network synchronization protocol (NSP), provides the ability to establish and maintain individual connections with specified synchronization characteristics. The upper level, the application synchronization protocol (ASP), supports an integrated synchronization service for multimedia applications. The ASP identifies the temporal relationships among an applications data objects and manages the synchronization of arriving data for playout. The proposed NSP and ASP are mapped to the session and application layers of the open-systems-interconnection (OSI) reference model, respectively. >

A digital on-demand video service supporting content-based queries

Video-on-demand represents a key demonstrative application for enabling multimedia technology in communication, database, and interface research. This application requires solving a number of diverse technical problems including the data synchronization problem for time-dependent data delivery. In this paper we describe the general requirements of video-on-demand and introduce a system supporting content-based retrieval and playback for the structure and content of digital motion pictures. In our model we capture domain-specific information for motion pictures and provide access to individual scenes of movies through queries on a temporal database. We describe our implementation of this service using existing workstation and storage technology.

An Information Propagation Scheme for VANETs

A goal in Vehicular Ad hoc Networks (VANETs) is to enable the dissemination of traffic and road conditions such as local congestion and surface ice as detected by independently moving vehicles. This activity known as Information Warning Functions is useful for vehicles on the highway and enables early reaction. This problem can be described as the direc- tional propagation of information originating from linearly- distributed mobile nodes on a rectilinear plane. By using limited-range packet radios and attribute-based routing, we are able to isolate vehicular from network traffic and permit directional propagation of messages outward from the point of origin. For example, it is desirable to propagate the occurrence of congestion created by an accident in both the forward and backward directions on a highway. We assume the use of multi-hop routing in clusters of connected vehicles to achieve a propagation rate that exceeds the speeds of individual carrier vehicles. We characterize the bounds of information propagation under various traffic patterns and describe a new technique and algorithm that can achieve these limits. We also show an implementation of the dissemination algorithm as a routing protocol using a combination of MANET (mobile ad hoc networking) and DTN (delay tolerant networking) methodologies.

A Survey of Technologies for Parsing and Indexing Digital Video1

Abstract In the future we.envision systems that will provide video information delivery services to customers on a very large scale. These systems must provide customers with mechanisms to select programs of their choice from live broadcasts. Customers should also be provided with easy means of browsing and accessing prerecorded digital data (e.g., distributed digital multimedia libraries), and downloading data from other information sources. To be viable for such large information sets, these systems must understand customer preferences and tailor the available information to the customers needs. To support this vision, a number of issues must be addressed and obstacles overcome. Intuitive interfaces, powerful query formulation and evaluation techniques, comprehensive data models, and flexible presentation functionalities must be developed. To realize these components, an effective query evaluation engine with the capabilities of query resolution in different content-specific formats (e.g., by graphics, by image, by sound) and in different domain-specific models (e.g., database of movies, database of newsclips) should be present. Additionally, the digital video database will require an efficient indexing system for easy access to the stored information. In this paper we discuss existing research trends in this area and requirements for future data delivery systems. An overview of video indexing is presented followed by a discussion on current indexing techniques.

Network considerations for distributed multimedia object composition and communication

Terminology is defined, and issues related to providing temporal data integration in a distributed environment are identified. Current technological approaches to the issues are reviewed, and the state of the art is assessed. A unified model for synchronization at three levels, based on previously reviewed approaches, is presented. Directions for future efforts are indicated.<<ETX>>

Spatio-temporal composition of distributed multimedia objects for value-added networks

The overall process necessary to perform spatial and temporal data composition for a distributed multimedia information system is addressed. With respect to delays introduced through the network, it is found that temporal composition can be most suitably achieved at the workstation. Spatial composition is most effectively performed in a hierarchical fashion as dictated by the availability of system resources. The subsequent composition methodology combines spatial and temporal composition as a network service. Database organizations and data distributions are also investigated, and spatial and temporal composition functions and their composition into the network architecture are discussed. The issue of mapping the composition process onto the network resources as a value-added service is also addressed.<<ETX>>

Popularity-based assignment of movies to storage devices in a video-on-demand system

A video-on-demand server must satisfy a large customer base and a diverse archive of movies under changing movie popularity and daily load peaks. These requirements must be satisfied under the constraints imposed by storage device costs, capacities, I/O bandwidths, and geographic locations. In this paper we describe a partitioning of video data (movies) onto a video-on-demand storage hierarchy to achieve efficient storage and I/O bandwidth use. Our approach uses a probabilistic model of movie popularity in data distribution and replication to balance user requests with available disk I/O bandwidth. The results can be applied in the design of a general, distributed video-on-demand system.