NC State University

Department of Computer Science Colloquia 1999-2000

Date: Wednesday, March 22, 2000
Time: 3:30 PM (talk)
Place: Withers 402A, NCSU Historical Campus (click for courtesy parking request)

Speaker: Surendar Chandra, Computer Science, Duke University

Quality Aware Transcoding:  An Application Level Technique to Dynamically Manage Wide-Area Resources

Abstract: The Web is emerging as the primary data dissemination and e-commerce mechanism. Popular web servers experience periods of bursty load from flash crowds. The problem of bursty traffic is compounded by the proliferation of inexpensive devices that can create, share and consume multimedia objects. A wider audience is encouraging e-commerce sites to use multimedia objects extensively. Multimedia objects, which tend to be large, are placing enormous strains on the network infrastructure. Web services need to dynamically manage available computation and network resources because of these highly bursty and demanding access patterns. Transcoding is a promising technology that allows systems to effect a quality-versus-size tradeoff on multimedia objects. Transcoding can be used to dynamically customize objects for the prevailing operating environment.

In this talk, I will present image transcoding as an application level technique to dynamically customize content. First, I analyze characteristics of Web images to choose appropriate transcoding technologies.  Next, I quantify the quality versus size trade-off characteristics of a promising transcoding algorithm. I then use this informed technique in a Web service for providing bandwidth consumption control, while providing differentiated Quality of Service. This technology also allows Web services to customize objects for clients accessing the Web using various network technologies.  By understanding the image characteristics, informed transcoding avoids unnecessary operations that lose quality as well as place unnecessary loads on the infrastructure. Through an implementation of informed transcoding in a popular Web server, I demonstrate how it achieves these goals.

Short Bio: Surendar Chandra is an Experimental Computer Science student at Duke University. His research interests lie in the areas of mobile computing, distributed systems, operating systems, computer networks and WWW issues. He received his undergraduate degree in Computer Science from Anna University, India in 1988. He received the M.S degree in Computer Science from Worcester Polytechnic Institute, Worcester MA in 1993. He is a student member of ACM (SIGOPS and SIGMOBILE), USENIX and IEEE.

Host: Edward Gehringer, Computer Science, NCSU

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