Dinesh Venkatesh

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.

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.

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.

Probabilistic 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.

SELECTION AND DISSEMINATION OF DIGITAL VIDEO VIA THE VIRTUAL VIDEO BROWSER

The Virtual Video Browser (VVB) is a manifestation of our mechanisms for the location, identification, and delivery of digital audio and video in a distributed system which can be extended to several application domains including multimedia-based home entertainment, catalog shopping, and distance learning. In the following sections we describe the VVB software application designed to allow the interactive browsing and content-based query of a video database and to facilitate the subsequent playout of selected titles.

Video scene decomposition with the motion picture parser

A motion picture can be modeled as a composition of many scenes where each scene is comprised of multiple shots. Thus, a conventional movie is a sequential aggregation of a large number of disparate image sequences. Within each image sequence or shot, there is consistency in image content and dynamics. This consistency in dynamics can be used in identifying scene changes for video segment decomposition and for techniques to improve data compression. We have developed an algorithm to use these dynamics for scene change detection and the decomposition of video streams into constituent logical shots. The algorithm uses intraframe image complexity and identifies scene transitions by considering short-term temporal dynamics. The algorithm has shown to be effective for detecting both abrupt scene changes (cuts) as well as smooth scene changes (fades and dissolves). This algorithm is used in an application we have developed called the Motion Picture Parser (MPP). The MPP automates the process of tagging segments of motion-JPEG-compressed movies. Segments are also tagged for subsequent semantic content-based retrieval in units of shots and scenes. The MPP application consists of a graphical user interface with various editing controls.

Client-server metadata management for the delivery of movies in a video-on-demand system

Describes a metadata mechanism for location, identification, and delivery of continuous media in the form of digital motion pictures and in the context of a distributed system. The metadata mechanism and supporting protocols are based on the client-server model. The mechanism can be applied to numerous application domains including multimedia-based home entertainment, catalog shopping, distance learning, and distributed-interactive classrooms. We demonstrate the practicality of our the mechanisms through a prototype application based on home entertainment.<<ETX>>

Dynamic Service Aggregation for Efficient Use of Resource in Interactive Video Delivery

To support future interactive information delivery services there is a need to balance individual interactivity with the desire to maximize the number of supported sessions. Currently, few techniques have demonstrated the ability to renegotiate and scale service parameters per session in progress as required to adapt to differing terminal equipment characteristics and network congestion. This paper addresses this problem through the definition of decomposable service groups that permit aggregation of interactivity, terminal characteristics, and levels of service scaling. The proposed approach applies the characteristics of end applications and data storage requirements to the design of a data scaling mechanism.

A Storage and Retrieval Technique for Scalable Delivery of MPEG-Encoded Video

Concurrent retrieval of continuous media from a physical storage device can be achieved by interleaving data and providing a suitable scheduling algorithm. Scheduling approaches that exploit gains from statistical multiplexing are susceptible to a nonzero probability of frame loss due to the variable-bit-rate characteristic of compressed video. With interframe encoding schemes (such as specified by the MPEG standard), the losses propagate, resulting in a net loss of frames that exceeds the fraction of lost data. In this paper, we describe a mechanism for the storage and retrieval of MPEG-encoded video from a single disk storage system. The scheme balances the need for the reliable delivery of MPEG frames with the desire to support the largest number of sessions. Our approach reorganizes the MPEG-encoded video stream based on the relative importance of the frames and maps them to the storage device geometry. The reorganization reduces the impact of frames lost due to missed deadlines and distributes the frame losses over time and among sessions. Simulation results show that the new approach improves performance when compared to conventional storage and scheduling schemes.

Investigation of web server access as a basis for designing video-on-demand systems

The performance of a video-on-demand server is affected by the dynamics of user accesses behavior. Most existing efforts consider static user request distributions in their design which can lead to poor performance if the accesses are different from that predicted. Even the use of a video store model to characterize user requests fails to account for the interactive nature of access. This suggests that better models for characterizing user behavior are necessary. In the recent past, the World Wide Web has become the most popular means for interactive information delivery. The World Wide Web represents a truly interactive medium with the user having complete control over presentation. Moreover, the performance bottleneck in the World Wide Web is more often the network than the server making it an ideal candidate to understand issues in serving interactive video. In this paper we study access behavior in a World Wide Web server and techniques to apply these observations in the design of a video- on-demand server.