An Infrastructure for the Real-Time Delivery of High Quality Continuous Media from Distributed Scalable Servers to Multiple Clients

Contact Information

University of Southern California

Computer Science Department SAL 300

Los Angeles, CA 90089-0781

Phone: (213) 740-8162

Fax : (213) 740-5807


List of Supported Students and Staff 

Senior Investigator: Prof. Roger Zimmermann
Ph.D. Students: Didi Yao, Farnoush Banaei-Kashani and Mehrdad Jahangiri
Project Award Information

Award Number: IIS-0082826
09/01/2000 -- 08/31/2003
Title: An Infrastructure for the Real-Time Delivery of High Quality Continuous Media from Distributed Scalable Servers to Multiple Clients


Continuous Media Servers, Real-time Streaming, Scalable Servers, Distributed Servers, Multimedia Infrastructure

Project Summary

Several large-scale IT applications are enabled by the design, implementation and evaluation of a scalable real-time streaming media architecture. Large volumes of real-time data are stored, maintained, and retrieved online. Popular examples of real-time media include video and audio, while less familiar examples are haptic and avatar data. The real-time end-to-end delivery of very high quality (megabits per second) media cannot be supported with the current Internet-based infrastructure due to the lack of a scalable server architecture as well as a missing global resource management protocol.

We are in the process of completing the design and implementation of our Yima streaming architecture, which consist of 1) a scalable, high performance, and real-time media server, 2) real-time network streaming paradigm and 3) several video and audio clients.  In addition, we are working on the design and implementation of GMeN (Global Media Network), a server-level distributed streaming architecture for cost-efficient delivery of continuous media to geographically distributed clients. Also, with P2PS (Peer-to-Peer Streaming) we investigate the client-level distribution of service that pushes the streaming task to the edges/users.

The impact of this architecture is on both the server design as well as the online multimedia content. Furthermore, the realization of such an infrastructure is enabling large scale applications such as video-on-demand, news-on-demand, distance learning and scientific exploration and visualization. These applications, in turn, will be promoting teaching, training, and learning as well as enhancing scientific and technological understanding.

Publications and Products

The following is a list of publications that are directly related to the topic of this grant and within which this ITR grant has been acknowledged.  Several other research publications that have acknowledged this grant but are not directly related can be found at:

  • Cyrus Shahabi, Roger Zimmermann, Kun Fu and Didi Yao, Yima: A Second Generation of Continuous Media Servers, To Appear in the IEEE Computer Magazine, June 2002
  • Cyrus Shahabi, Farnoush Banaei-Kashani, Decentralized Resource Management for a Distributed Continuous Media Server, IEEE Transactions on Parallel and Distributed Systems (TPDS), Vol. 13, No. 6, June 2002
  • Cyrus Shahabi, Shahram Ghandeharizadeh, Surajit Chaudhuri, On Scheduling Atomic and Composite Continuous Media Objects, IEEE Transactions on Knowledge and Data Engineering (TKDE), Vol. 14, No. 2, pages 447-455, March/April 2002
  • Ashish Goel, Cyrus Shahabi, Shu-Yuen Didi Yao, and Roger Zimmermann, SCADDAR: An Efficient Randomized Technique to Reorganize Continuous Media Blocks, IEEE International Conference on Data Engineering (ICDE'2002), San Jose, California, February 2002
  • Roger Zimmermann, Kun Fu, Cyrus Shahabi, Didi Yao, and Hong Zhu,Yima: Design and Evaluation of a Streaming Media System for Residential Broadband Services. , VLDB 2001 Workshop on Databases in Telecommunications (DBTel 2001) , Rome, Italy , September 2001

 Other Products:

  • An IEEE educational CD-ROM has been developed, teaching the concepts of streaming architectures.
  • A Prentice Hall book contract has been signed on the topic of streaming architectures.  The book will include a single-node version of Yima software on CD-ROM.
  • A video demonstration of Yima is available on the project web site.

Project Impact

  • Several technologies developed under this research project have been licensed to industry.  Super-streaming has been licensed to BTG Inc.; Yima Jade, RedHi-DM, and SCADDAR have been licensed to The GlobalTheater Inc ( ).
  • A research license for Yima Jade has also been provided to Wong's International USA Corp. ( )
  • A test installation of Yima server has been operational at The GlobalTheater since October 2000.
  • Several research prototypes of Yima (with different clients) have been demonstrated to NSF and industry visitors of the USC's Integrated Media Systems Center , an NSF Engineering Research Center.  A major press release and demonstration of the IMSC's RMI (Remote Media Immersion) experiment that is scheduled for May 2002 will include Yima as its main streaming infrastructure.
  • Yima’s performance has been evaluated in realistic setups by co-locating it in an IMSC industry partner, AboveNet Inc., data center at El Segundo, CA.

Goals, Objectives, and Targeted Activities

The goal of this project is to design and develop an architecture for real-time storage and playback of several continuous media streams through heterogeneous, scalable and distributed servers utilizing IP networks (e.g., Internet). This architecture enables applications such as video-on-demand, employee training and distance learning on a large scale.

The main component of our architecture is a scalable media server, termed YimaYima is based on a cluster design comprised of multiple nodes of off-the-shelf personal computers resulting in both a scalable and cost-effective implementation.  The network component of our architecture provides a selective retransmission scheme that improves the rendering quality of the transmitted streams with real-world networks that suffer from occasional packet loss. This scheme is shown to be more effective for real-time media as compared to conventional UDP and TCP schemes.  Yima's SCADDAR algorithm allows incremental storage system growth while (a) the system continues operation, (b) the minimal amount of data is reorganized, and (c) the system continues to be load balanced.  Finally, we are investigating a distributed architecture that consists of several Yima server nodes inter-connected through a controlled network.  We have discovered that a decentralized management of the media objects (e.g., video clips), as opposed to a centralized (e.g., directory-service) design, results in more efficient and robust architecture. This fully decentralized design is also consistent with the recently popular peer-to-peer architectures. We have developed a working prototype of Yima that is designed to be media independent to stream media types such as MPEG-4, uncompressed immersive audio, panoramic (360 degree) video and High Definition TV.  Our Multi-Threshold Flow Control (MTFC) algorithm allows the smoothing of variable bit-rate media transmissions without a priori knowledge of the actual bit-rate. It improves resource utilization and can be applied to (a) live streams and (b) stored streams without requiring any server side pre-processing. We have also shown the ability of Yima to allow multiple streams be rendered in tight synchronization over the public Internet. For example, panoramic video streams that are comprised of five individual streams can be displayed frame-locked.

Yima distinguishes itself from other similar efforts due to its: 1) independence from media type, 2) frame/sample accurate inter-stream synchronization, 3) compliance with industry standards (e.g., RTSP, RTP, MP4), 4) selective retransmission protocol, 5) scalable design, and 6) multi-threshold buffering to support variable-bitrate media (e.g., MPEG-2).

Project References

A video demonstration of Yima is available on the project web site. Several publications are also available as outlined in the "Publications and Products" section.

Area Background

A growing number of immersive and multimedia applications store, maintain, and retrieve large volumes of real-time data where the data is required to be available online.  We denote these data types collectively as "continuous media", or CM for short.  Continuous media is distinguished from traditional textual and record-based media in two ways.  First, the retrieval and display of continuous media are subject to real-time constraints.  If the real-time constraints are not satisfied, the display may suffer from disruptions and delays termed hiccups.  Second, continuous media objects are large in size.  A two-hour MPEG-2 video with a 4-megabit per second (Mb/s) bandwidth requirement is 3.6 gigabyte (GB) in size.  Popular examples of CM are video and audio objects, while less familiar examples are haptic, avatar and application coordination data.  We focus on those CM objects that are of very high quality requiring bandwidths in the order of megabits per second.

Area References
S. Ghandeharizadeh and C. Shahabi, “Distributed Multimedia Systems.” In Wiley Encyclopedia of Electrical and Electronics Engineering, Editor: J. G. Webster, Volume 5, 1999 John Wiley & Sons, Inc.

Potential Related Projects

Some of the resource reservation and path selection protocols designed for our fully decentralized video servers are applicable to the peer-to-peer architectures (refer to the TPDS’02 paper). Our approach for scaling up the number of disk nodes, SCADDAR, can be adapted for the design of expandable storage systems for data streams (refer to the ICDE’02 paper).