P.V. Rangan

University of California, San Diego, San Diego, CA, United States

Are you P.V. Rangan?

Claim your profile

Publications (16)19.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: CD-ROMs have proliferated as a distribution media for desktop machines for a large variety of multimedia applications. We look at issues related to the single-user desktop environment. Since these multimedia applications are highly interactive in nature, we take a pragmatic approach, and have made a detailed study of the multimedia application behavior in terms of the I/O request patterns generated to the CD-ROM subsystem by tracing these patterns. We discuss prefetch buffer design and seek time characteristics in the context of the analysis of these traces. We show that it is best to place multimedia streams near the center of the CD-ROM. We present the parameters of an adaptive main-memory hosted cache that receives caching hints from the application to reduce the latency when the user moves from one node of the hypergraph to another. We show that short-throw seeks of distance 100 are the most important. We look at the use of CD-ROMs in a video on demand server (VoD) and discuss the problem of scheduling multiple request streams and buffer management in this scenario. We adapt C-SCAN (Circular SCAN) algorithm to suit the CD-ROM drive characteristics and prove that it is optimal in terms of buffer size management. We provide computationally inexpensive relations by which this algorithm can be implemented. We then propose a `constant-full-load' admission control algorithm which admits new request streams from a pool of dummy requests without disrupting the continuity of playback of the previous request streams. The algorithm also supports operations such as fast forward and replay
    Multimedia Computing and Systems, 1996., Proceedings of the Third IEEE International Conference on; 07/1996
  • Source
    P.V. Rangan, S.S. Kumar, S. Rajan
    [Show abstract] [Hide abstract]
    ABSTRACT: The requirement of continuous retrieval, and the presence of multiple media streams whose display must proceed in a mutually synchronized manner are the distinguishing features that are unique to digital multimedia. In the emerging international multimedia encoding standard MPEG, continuity and synchronization are handled at different layers of the multimedia stream. The authors discuss how they are specified and propose techniques for their implementation within a distributed multimedia environment
    IEEE Journal on Selected Areas in Communications 02/1996; · 3.12 Impact Factor
  • Source
    A. Cohen, W.A. Burkhard, P.V. Rangan
    [Show abstract] [Hide abstract]
    ABSTRACT: We develop a reliable disk array based storage architecture for digital video retrieval. Our goals are two fold: maximizing the number of concurrent real time sessions while minimizing the buffering requirements, and ensuring a high degree of reliability. The first goal is achieved by adopting a pipelined approach and by reducing latencies through specialized disk caching and constrained data placement schemes. The second goal is achieved by dividing the disks into RAID 3 reliability groups which serve as pipeline stages. We note that the buffering requirement decreases as the number of groups increases. To improve the performance further, we introduce two techniques for more efficient movie retrieval: on arrival caching, and interleaved annular layout. We present a case study of the performance of these techniques which shows a significant improvement when they are incorporated
    Multimedia Computing and Systems, 1995., Proceedings of the International Conference on; 06/1995
  • [Show abstract] [Hide abstract]
    ABSTRACT: At the University of California, San Diego, we are developing architectures and technologies targeted at the practical realization of interactive multimedia services to subscriber communities. We believe that a key deciding factor for the feasibility of interactive multimedia services is their economic viability. We propose techniques for information caching as a fundamental means of optimizing per user costs of multimedia distribution
    Community Networking Integrated Multimedia Services to the Home, 1994., Proceedings of the 1st International Workshop on; 08/1994
  • [Show abstract] [Hide abstract]
    ABSTRACT: The synergy between computing and information systems promises to herald a new epoch in which users not only have access to mundane services, such as television, radio, and telephones, but they also have access to an entirely new variety of entertainment services that are automatically customized to suit their individual needs. The authors explore the architectural considerations that underlie the realization of personalized multimedia entertainment services over metropolitan-area broadband networks, and devise near-optimal information caching strategies to determine when, where, and for how long video programs must be cached, so as to minimize the cumulative storage and network costs borne by users
    Multimedia Computing and Systems, 1994., Proceedings of the International Conference on; 06/1994
  • Source
    P.V. Rangan, H.M. Vin
    [Show abstract] [Hide abstract]
    ABSTRACT: The problem of collocational storage of media strands, which are sequences of continuously recorded audio samples or video frames, on disk to support the integration of storage and transmission of multimedia data with computing is examined. A model that relates disk and device characteristics to the playback rates of media strands and derives storage patterns so as to guarantee continuous retrieval of media strands is presented. To efficiently utilize the disk space, mechanisms for merging storage patterns of multiple media strands by filling the gaps between media blocks of one strand with media blocks of other strands are developed. Both an online algorithm suitable for merging a new media strand into a set of already stored strands and an offline merging algorithm that can be applied a priori to the storage of a set of media strands before any of them have been stored on disk are proposed. As a consequence of merging, storage patterns of media strands may become perturbed slightly. To compensate for this read-ahead and buffering are required so that continuity of retrieval remains satisfied are also presented
    IEEE Transactions on Knowledge and Data Engineering 09/1993; · 1.89 Impact Factor
  • Source
    S. Ramanathan, P.V. Rangan
    [Show abstract] [Hide abstract]
    ABSTRACT: The authors have developed intermedia synchronization techniques for multimedia on-demand retrieval over integrated networks in the absence of global clocks. In these techniques, multimedia servers use lightweight messages called feedback units transmitted by media display sites (such as audiophones and videophones, generically referred to as mediaphones) to detect asynchronies among those sites. They present strategies by which the multimedia server can adaptively control the feedback transmission rate from that mediaphone, so as to minimize the associated overheads without permitting the asynchrony to exceed tolerable limits. They compare the performance of various resynchronization policies such as conservative, aggressive, and probabilistic. Performance evaluation of the feedback techniques indicates that their overheads are negligible; for a typical audio/video playback environment, the feedback frequency was about one in a hundred
    IEEE/ACM Transactions on Networking 05/1993; 1(2):246-260. · 2.01 Impact Factor
  • P.V. Rangan, H.M. Vin, S. Ramanathan
    [Show abstract] [Hide abstract]
    ABSTRACT: The problem of media mixing that arises in teleconferencing applications such as teleorchestra is addressed. The mixing algorithm presented minimizes the difference between generation times of the media packets that are being mixed together in the absence of globally synchronized clocks, but in the presence of jitter in communication delays on packet switched networks. In order to support applications, such as teleorchestra, that involve a large number of participants, hierarchical mixing architectures are proposed, and it is shown that they are an order of magnitude more scalable than purely centralized or distributed architectures. Furthermore, mechanisms for minimizing the delays incurred by mixing in various communication architectures are presented. The mixing algorithms are implemented on a network of workstations connected by Ethernets, and the performance of various mixing architectures is experimentally evaluated. The results reveal the maximum number of participants that can be supported in a conference
    IEEE/ACM Transactions on Networking 03/1993; 1(1):20-30. · 2.01 Impact Factor
  • P.V. Rangan, H.M. Vin, S. Ramanathan
    [Show abstract] [Hide abstract]
    ABSTRACT: A quantitative study of techniques for designing a high-performance multiuser multimedia on-demand information service is presented. The problem of maintaining continuity of playback of each media stream in the presence of multiple subscriber requests is formulated, and admission control algorithms that permit a multimedia server to satisfy the maximum number of subscribers simultaneously are presented. A feedback technique in which a multimedia service uses lightweight messages called feedback units that are transmitted back to it by subscribers' mediaphones to detect asynchrony among them and steer them back to synchrony thereafter is presented. The feedback technique guarantees synchronous playback of media streams transmitted by the multimedia server to subscribers over metropolitan-area networks.< >
    IEEE Communications Magazine 08/1992; · 3.66 Impact Factor
  • P.V. Rangan
    [Show abstract] [Hide abstract]
    ABSTRACT: Not Available
    Consumer Electronics, 1992. Digest of Technical Papers. ICCE., IEEE 1992 International Conference on; 07/1992
  • S. Ramanathan, P.V. Rangan, H.M. Vin
    [Show abstract] [Hide abstract]
    ABSTRACT: It is pointed out that the integration of virtual reality techniques with multimedia teleconferencing leads to the development of tele-virtual conferencing systems, which synthesize panoramic, life-like three-dimensional video images and stereophonic audio. The authors investigate the architectural requirements of such systems and propose a high-level design of an intelligent multimedia interface unit (IMIU) capable of supporting tele-virtual conferencing in multimedia home computers. The IMIU is capable of supporting panoramic, life-like three-dimensional video images and stereophonic audio, so as to synthesize tele-virtual conferencing environments
    IEEE Transactions on Consumer Electronics 06/1992; · 1.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Not Available
    Multimedia Communications, 1992. MULTIMEDIA '92. 4th IEEE ComSoc International Workshop on; 05/1992
  • P.V. Rangan, D.C. Swinehart
    [Show abstract] [Hide abstract]
    ABSTRACT: Software mechanisms that make use of analog transmission and storage of video for computer-controlled video communication and file storage are described. The authors extended the Etherphone voice management system to support video conferencing and file storage. The software mechanisms for conference management consist of a central connection manager, and video and user interface agents running on client workstations. A conferencing architecture that supports multiplicity in the number of conferences and media is presented. The video file server stores and retrieves full-motion video information within conferences. It uses optical disks to store video frames and builds a high-level file and directory interface. The user interface to the directory interface is a multimedia document editor that permits video annotations to be freely interspersed with text. The performance of the system, which spans multiple media networks, has been highly satisfactory
    IEEE Journal on Selected Areas in Communications 01/1992; · 3.12 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The latest extension of the Etherphone project is described. It creates a powerful conferencing system that lets users control their participation in multiple conferences across multimedia networks. The emphasis is on the software mechanisms that support its new features: first, a Sparcstation facility called Phoenix that extends the Etherphone software architecture to permit more flexible conferencing and to control Sparcstation-based Ethernet audio transmission, and, second, the integration of the Phoenix capabilities with Macaw, the earlier video extensions. Also described is a multicast packet protocol for audio transmission, which reimplements and extends the earlier special-purpose protocols, adding per-channel volume control and full support for the extended conferencing modes.< >
    Computer 11/1991; · 1.68 Impact Factor
  • P. Venkat Rangan, D. C. Swinehart
    IEEE Journal on Selected Areas in Communications - JSAC.
  • P. V. Rangan, H. M. Vin