Researcher Named Top Young Investigator at Key Imaging Conference

An HP Labs researcher working in the area of streaming media has received the Visual Communications and Image Processing (VCIP) 2001 Young Investigator Best Paper Award.

John Apostolopoulos, a senior research scientist in the Streaming Media Systems Group, was recognized for his paper, "Reliable Video Communication Over Lossy Packet Networks using Multiple State Encoding and Path Diversity."

Just released as HP Labs technical report HPL-2001-319, the paper presents a system for providing reliable video communication over lossy packet networks such as the Internet.

"This outstanding paper . not only advances the state of the art, but is also presented in a very clear and readable fashion," VCIP officials said in their commendation. "It will undoubtedly inspire further research in this area."

Apostolopoulos, who joined HP Labs four years ago, works in video communication and is part of a team that is designing a streaming media content delivery network. He is tackling the problem of high-quality video communication over wired and wireless networks afflicted by packet loss and burst errors. These losses can cause significant reductions in video quality, including temporary breaks (such as freeze frames) and potentially even complete loss of video.

Apostolopoulos proposed one of the first multiple description video coders. In this case, video is coded into two or more complementary descriptions so that even if one description is lost, viewers can still decode useful video. When both descriptions are received, the video will be of maximum quality.

Next, he collaborated with MIT Professor Gregory Wornell (who spent part of his sabbatical at HP Labs in Fall 1999) on the problem of improving communication over lossy packet networks, and examined the idea of using diversity over networks (that is, path diversity) in which multiple network paths are used at the same time.

In the VCIP paper, Apostolopoulos combined multiple description video coding with path diversity over packet networks, developed system architectures for this process, and showed that this system leads to significant improvements in video communication as compared to conventional systems.

"At a high level, the idea is simple and intuitive, you send one description over one path and a second description over a second path, so if you lose one, you still get the other and can reconstruct usable video," he said.

Apostolopoulos and other researchers in the Mobile Streaming Media Systems Team are now working with NTT DoCoMo, Japan's premier mobile communications company, to design a mobile streaming media content delivery network (MSM-CDN).

Apostolopoulos has a consulting assistant professor appointment at Stanford, where he teaches the graduate-level course, Digital Video Processing. He has also lectured on video compression and video streaming at MIT. He is actively involved with the IEEE Signal Processing Society, and is a member of IEEE Image and Multidimensional Digital Signal Processing (IMDSP) Technical Committee.

He received his BS, MS, and PhD degrees in Electrical Engineering and Computer Science from MIT.