NEMESYS
Networked and Embedded Multimedia Systems Research Group,
School of Computing, National University of Singapore
About Us

The NEMESYS research group conducts systems research with a special focus on multimedia applications. Our interest spans distributed systems, operating systems, embedded systems, and programming systems. In particular, we are studying how to provide systems support for multimedia data types (video, audio, graphics) in the context of applications such as video on demand, tele-conferencing, webcast productions, computer games, video surveillance, running on personal computers and mobile devices.

People

Axel Carlier
Research Assistant
Axel received a Bachelor of Science in Computer Science and Applied Mathematics from ENSEEIHT, Toulouse (France). His research interests are in multimedia.
Wei Cheng
Ph.D. Candidate
Wei Cheng received his Master degree in Computer Science from Fudan University, Shanghai, China in 2005, and joined the Ph.D. program in NUS in the same year. His thesis topic is on streaming of progressive meshes. [Home Page]
Ravindra Guntur
Research Fellow
Ravi graduated with a Ph.D. in Computer Science from IIS, Bangalore, India, in 2005. He worked in HP and Motorola Labs before joining NUS as a postdoctoral researcher. Ravi research interests are in multimedia systems and NLP. [Home Page]
Pavel Korshunov
Ph.D. Candidate
Pasha obtained his Master degree from St. Petersburg State University in 2002 and joined NUS as a Ph.D. student in 2003. Pasha worked on the DAVIS project, in particular, on reducing the data rate of surveillance video streams without affecting the accuracy of automated surveillance algorithms. He spent half a year from July - December 07 as an intern in FXPAL. [Home Page]
Dan Liu
Ph.D. Candidate
Dan graduated from Tianjing University and joined NUS's Ph.D. program in 2007. Her current research interest is in peer-to-peer streaming.
Manoranjan Mohanty
Ph.D. Candidate
Manoranjan obtained his Master degree from Jawaharlal Nehru University (JNU), New Delhi, India in 2007. Before joining NUS as a Ph.D. student in 2009, He worked as Systems Engineer in IBM and R&D Engineer in OSI. He is working on real time, 4D medical image visualization.
Chanaka Aruna Munasinghe
Ph.D. Candidate
Chanaka obtained his BSc in Computer Engineering from University of Peradeniya, Sri Lanka in 2008. He joined NUS as a Ph.D. student in 2009 and he is currently working on scalability issues of networked virtual environments. [Home Page]
Wei Tsang Ooi
Assistant Professor
Wei Tsang received his Ph.D. in Computer Science from Cornell University, Ithaca, NY in 2001. He later spent a year as postdoc at Berkeley Multimedia Research Center in U.C. Berkeley. He joined NUS as an Assistant Professor in 2002. His research interests include multimedia, computer networking, mobile computing, distributed systems. [Home Page]
Balaji Raman
Ph.D. Candidate
Balaji received his Master degree in Computer Science from NUS in 2004 and continued to study his Ph.D. in the same department. He is jointly supervised by Wei Tsang Ooi and Samarjit Chakraborty. Balaji's thesis is on modeling and analysis of multimedia applications on system-on-chip platform. He was an intern at EPFL from Jan - Jun of 2008. [Home Page]
Sameer Samarth
Master of Computing Student
Sameer completed his under-graduation from Bangalore, India. After his graduation he worked in the software industry for over 3 years developing firmware and other low level code for Hewlett Packard printers. Currently, he is pursuing his Masters degree at the School of Computing, NUS. His research interest is in distributed systems, embedded systems and multimedia.
Satish Verma
Ph.D. Candidate
Satish received his bachelor degree from IIT, India and his master degree from EPFL, Switzerland. He joined the department of computer science as a Ph.D. student in 2003 and is working on modeling and improving the performance of gossip protocols. [Home Page]
Jinyu Xu
Ph.D. Candidate
Jinyu graduated from Shandong University and joined NUS in 2009. His research area is in mesh network streaming.
Shanghong Zhao
Ph.D. Candidate
Shanghong received his Bachelor degree in Computer Science from Fudan University, Shanghai, China, and joined the Ph.D. program in NUS in 2009. He is now working on streaming of progressive meshes.
Zhengwei Zhao
Ph.D. Candidate
Zhenwei graduated with Bachelor of Computing (First Class Honors) and minor in Mathematics from National University of Singapore in June 2009. In the same year, He joined the Ph.D program of NUS Graduate School for Integrative Sciences and Engineering. His research interests are in the area of multimedia systems, distributed computing and security related issues. [Home Page]
Minhui Zhu
Ph.D. Candidate
Minhui received her Bachelor degree in Computer Science from Xi'an Jiaotong University, Xi'an, China, in 2009, and joined the Ph.D. program in NUS in the same year. She is currently working on 3D rendering on mobile devices.

Alumni

Yanhong Liu
Ph.D., 2007, Postdoc at VERIMAG, France.
Yanhong received his Master degree from Chinese Academy of Science and joined NUS's Ph.D. program in 2002. He is jointly supervised by Samarjit Chakraborty and Wei Tsang Ooi. He graduated in 2007, and a thesis on applying network calculus to model system-on-chip platforms for multimedia applications. Yanhong is now a postdoc researcher at VERIMAG, France.
Lin Ma
Ph.D., Jun 2008, Macquarie Bank, Singapore
Lin received his Bachelor degree from Zhejiang University and join the Ph.D. program in NUS in 2002. He has worked on the Dimestr project and TCP UREL. Lin graduated in June 2008 and is now working in Macquarie Bank in Singapore. [Home Page]
Ransi Nilaksha De Silva
Research Assistant
Ransi graduated with Bachelor of Science (First Class Honors) from University of Colombo and a Master degree in Electrical Engineering from National University of Singapore. His research interests are in embedded systems design and virtual environments. Ransi was a reserach assistant with NeMeSys till Jan 2010.

Honors
  • Dean's Graduate Research Excellence Award Cheng Wei, August 2009
  • Best Paper Award ACM Multimedia 2008
  • President's Graduate Fellowship Balaji Raman, August 2007
  • Dean's Graduate Award Lin Ma, Mar 2007
  • Dean's Graduate Award Yanhong Liu, Jan 2005
  • Dean's Graduate Award Satish Verma, August 2005
  • Best Paper Candidate CODES+ISSS 2006
  • Best Paper Candidate DAC 2005
  • Best Paper Candidate ICCCN 2005
Projects

MALDIVES
Measurement and Analysis of Large Distributed VIrtual EnvironmentS
Previous research in DVE mainly based their design on assumptions on how avatars behave, and use randomly generated movements to evaluate their design. We believe that there is a gap between these assumptions and randomly generated movements to how real avatar behave. To bridge the gap, we collected a large number of avatar movement traces from Second Life. Our analysis of the traces lead to several new insights to design of caching, prefetching, zoning, load balancing in traditional client/server architecture as well as peer-to-peer DVE.
Cubist
3D Mesh Streaming
3D triangular mesh is becoming an increasingly important data type for networked applications such as digital museums, online games, and virtual worlds. A high quality 3D mesh can consists of billions of polygons, giving a total data size in the order of gigabytes, even after lossless compression. Disseminating such 3D meshes over a resource-constraint network for on-demand viewing and rendering presents many technical challenges. We are investigating how to efficiently and effectively support streaming of large 3D meshes to large number of clients over the Internet. This project is partially supported by MOE ARF Grant 232-000-306-112. (September 2007 - September 2009).
DAVIS
Distributed, Automated Video Surveillance
In next generation video surveillance system, video streams are not watched by humans most of the time, but, instead, are processed by automated software employing computer vision algorithms. Computer vision has a much lower requirements on video quality than human vision. Exploiting this fact, surveillance video streams can be sent at a low quality without affecting the accuracy of the vision algorithms.
TCP UREL
Unreliable TCP
We propose an alternative congestion controlled, unreliable transport protocol based on TCP. Unlike DCCP, our protocol is merely a TCP option, and therefore can be deployed immediately, is friendly to TCP, and evolves with TCP. The idea behind our proposal is simple -- put new data in retransmitted segments. An implementation on FreeBSD requires only 750 lines of code.
Plasma
A Scripting Language for Manipulating Media Streams
Plasma is a scripting language designed to make it easy to manipulate live media streams. One can easily compose a new stream from multiple media sources, including cameras, stored media files, and live streams. Plasma is event-based. One can bind an action to UI event (e.g. mouse click), network event (e.g., packet losses) or content (e.g. motion in video). Plasma is useful to building applications such as video surveillance and broadcast production.
Dimestr
Multi-source Media Streaming
Distributed media streaming, or multi-source media streaming, exploits both server and path diversity to improve the quality of the media streams received. Under this communication model, multiple senders collaboratively and simultaneously stream a media content to a receiver. Such model poses breaks some fundamental assumptions in traditional media streaming systems. We are investigating transport and application protocols to support this new model, in particular, in error control and congestion control.

Publications
2009
  • Integrated Optimization of Video Server Resource and Streaming Quality over Best-effort Network Hang Yu, Ee-Chien Chang, Wei Tsang Ooi, Mun Choon Chan, and Wei Cheng, IEEE Transactions on Circuits and Systems for Video Technology, 19(3), March 2009, 374--385.
  • Peer-Assisted View-Dependent Progressive Mesh Streaming Wei Cheng, Dan Liu, Wei Tsang Ooi, in the Proceedings of the 17th ACM International Multimedia Conference, 19-24 October 2009, Beijing, China.
  • Towards Characterizing User Interaction with Progressively Transmitted 3D Meshes Ransi Nilaksha De Silva, Wei Cheng, Dan Liu, Wei Tsang Ooi, Shengdong Zhao, in the Proceedings of the 17th ACM International Multimedia Conference, 19-24 October 2009, Beijing, China. (Short Paper)
  • A Demonstration of MobiTree: Progressive 3D Tree Models Streaming on Mobile Clients Andra Doran, Sebastien Mondet, Romulus Grigoras, Geraldine Morin, Wei Tsang Ooi, Frederick Boudon, in the Proceedings of the 17th ACM International Multimedia Conference, 19-24 October 2009, Beijing, China. (Demo Paper)
  • Avatar Mobility in User-created Networked Virtual Worlds: Measurements, Analysis, and Implications Huiguang Liang, Ransi Nilaksha De Silva, Wei Tsang Ooi, Mehul Motani Multimedia Tools and Applications, Published Online First (21 May 2009), doi:10.1007/s11042-009-0304-x. (An earlier version of this paper is published as arXiv:0807:2328)
  • A Stochastic Dynamic Traveling Salesman Problem with Hard Time Windows Tsung-Sheng Chang, Yat-Wah Wan, Wei Tsang Ooi, European Journal of Operational Research, 198(3), November 2009, 748-759.
2008
  • Textures in Second Life: Measurements and Analysis Huiguang Liang, Mehul Motani, Wei Tsang Ooi, in Proceedings of 2nd International Workshop on Peer-to-Peer Networked Virtual Environments (P2P-NVE), 8-10 December 2008, Melbourne, Australia. [pdf]
  • Equilibrium Analysis Through Separation of User and Network Behavior Y.C. Tay, Dinh Nguyen Tran, Eric Yi Liu, Wei Tsang Ooi, and Robert Morris, Computer Networks, 52(18), December 2008, 3405 -- 3420.
  • Streaming of Plants in Distributed Virtual Environments Sebastien Mondet, Wei Cheng, Geraldine Morin, Romulus Grigoras, Frederic Boudon, and Wei Tsang Ooi in the Proceedings of the 16th ACM International Multimedia Conference, 27-31 October 2008, Vancouver, BC, Canada. (Best Paper) (9 out of 50 Systems/Networking Track, 18%)
  • Receiver-Driven View-Dependent Streaming of Progressive Mesh Wei Cheng, Wei Tsang Ooi, In Proceedings of the 18th International Workshop on Network and Operating System Support for Digital Audio and Video (NOSSDAV), 28-30 May 2008. 17 out of 50 (34%) [pdf]
  • Techniques and Protocols for Distributed Media Streaming Lin Ma, Ph.D. Thesis, April 2008 [pdf]
2007
  • An Analytical Model for Progessive Mesh Streaming Wei Cheng, Wei Tsang Ooi, Sebastian Mondet, Romulus Grigoras, Geraldine Morin, In Proceedings of 15th ACM International Multimedia Conference, September 24-29, 200, Augsburg, Germany. 13 out of 63 (Systems/Networking Track, 20.6%) [pdf]
  • Application-specific Workload Shaping in Multimedia-enabled Personal Mobile Devices Balaji Raman, Samarjit Chakraborty, To appear in Proceedings of the ACM Transactions on Embedded Computing Systems (TECS), 2007. [pdf]
  • Reducing Data-Memory Footprint of Multimedia Applications by Delay Redistribution Balaji Raman, Samarjit Chakraborty, Wei Tsang Ooi, and Santanu Dutta, in Proceedings of Design Automation Conference (DAC), 4-8 June 2007, San Diego, California, USA. 153 out of 659 (23.2%) [pdf]
  • Congestion Control in Distributed Media Streaming Lin Ma, Wei Tsang Ooi, In Proceedings of the 26th Annual IEEE Conference on Computer Communications (INFOCOM 2007), 6-12 May 2007, Anchorage, Alaska, USA 252 out of 1400 (~18%) [pdf]
  • Plasma: A Scripting Language for Processing Media Streams Tao Zhu, Pavel Korshunov, Bing Liu, Wei Tsang Ooi, In Proceedings of ACM/SPIE Multimedia Computing and Networking (MMCN), 28 January - 1 February 2007, San Jose, CA. 18 out of 60 (30%) [pdf]
  • System-Level Modeling and Analysis of Multimedia-SoC Platforms Yanhong Liu, Ph.D. Thesis, Jan 2007 [pdf]
2006
  • Rate-Accuracy Tradeoff in Automated, Distributed Video Surveillance Systems Pavel Korshunov, In Proceedings of the 14th ACM International Conference on Multimedia, (MM 06), Doctoral Symposium, pages 887-889, Santa Barbara, California, USA, October 23-27, 2006. [pdf]
  • Application-specific Workload Shaping in Multimedia-enabled Personal Mobile Devices Balaji Raman, Samarjit Chakraborty, In Proceedings of the ACM International Conference on Hardware/Software Codesign and System Synthesis (CODES+ISSS), Seoul, October 22-25, 2006 Best Paper Candidate (among the top 2 papers) 46 out of 183 (25%) [pdf]
  • Analysis and Implications of Student Contact Patterns Derived from Campus Schedules Vikram Srinivasan, Mehul Motani, Wei Tsang Ooi, In Proceedings of the Twelfth Annual ACM International Conference on Mobile Computing and Networking (MobiCom), Los Angeles, CA, September 23-29, 2006. 35 out of 298 (11.7%) [pdf]
  • Games are Up for DVFS Yan Gu, Samarjit Chakraborty, Wei Tsang Ooi, In Proceedings of Design Automation Conference (DAC) San Francisco, CA, July 24-28, 2006 180 out of 865 (20.8%) [pdf]
  • SAX: A Tool for Studying Congestion-induced Surfer Behavior Dinh Nguyen Tran, Wei Tsang Ooi, Y.C. Tay, in Proceedings of Passive and Active Measurement Conference, Adelaide, Australia, March 30-31, 2006 21 out of 82 (25%) [pdf]
2005
  • Critical Video Quality for Distributed Automated Video Surveillance Pavel Korshunov, Wei Tsang Ooi, ACM Multimedia 2005, Singapore, 6-12 November 2005. [pdf]
  • Packetization of 3D Progressive Meshes for Streaming over Lossy Networks, Yan Gu, Wei Tsang Ooi, ICCCN 2005, San Diego, CA, 17-19 October 2005. Best Paper Candidate [pdf]
  • Cost-Quality Tradeoffs in MPEG-4 Decoding on Resource-Constrained Devices Yanhong Liu, Samarjit Chakraborty, Wei Tsang Ooi, Ashish Gupta, Subramanian Mohan, ESTIMedia 2005, New York, NY, 22-23 September 2005. [pdf]
  • Retransmission in Distributed Media Streaming, Lin Ma, Wei Tsang Ooi, NOSSDAV 2005, Skamania, WA, 12-14 June 2005. [pdf]
  • Meeting CPU Constraints by Delaying Playout of Multimedia Tasks, Balaji Raman, Samarjit Chakraborty, Wei Tsang Ooi, NOSSDAV 2005, Skamania, WA, 12-14 June 2005. [pdf]
  • Approximate VCCs: A New Characterization of Multimedia Workloads for System-level MpSoC Design, Yanhong Liu, Samarjit Chakraborty, Wei Tsang Ooi, DAC 2005, Anaheim, CA, 13-15 June 2005. Best Paper Candidate [pdf]
  • Dependency-aware Packetization Problem in Progressive Meshes, Yan Gu, INFOCOM 2005 (Poster), Miami, FL, March 2005.
  • Controlling Gossip Protocol Infection Pattern Using Adaptive Fanout, Satish Verma, Wei Tsang Ooi, ICDCS 2005, Columbus, OH, June 2005. [pdf]
  • Dagster: Contributor Aware End-Host Multicast for Media Streaming in Heterogeneous Environment, Wei Tsang Ooi, MMCN 2005, San Jose, CA, Jan 2005. [pdf]
2004
  • Processor Frequency Selection in Energy-Aware SoC Platform Design for Multimedia Applications, Yanhong Liu, Alexander Maxiaguine, Samarjit Chakraborty, Wei Tsang Ooi, RTSS 2004, Lisbon, Portugal, December 2004. [pdf]
  • Identifying Representative Workloads in Designing MpSoC Platforms for Media Processing, Alexander Maxiaguine, Yanhong Liu, Samarjit Chakraborty, Wei Tsang Ooi, ESTIMedia 2004, Stockholm, Sweden, September 2004. [pdf]
  • Hierarchical, Non-uniform Locality Sensitive Hashing and Its Application to Video Identification, Zixiang Yang, Wei Tsang Ooi, Qibin Sun, ICME 2004, Taipei, Taiwan, June 2004. [pdf]
  • Distributed Construction of Resource-Efficient Overlay Tree by Approximating MST, Yuan Li, Wei Tsang Ooi, ICME 2004, Taipei, Taiwan, June 2004. [pdf]
  • Layered Coding with Good Allocation Outperforms Multiple Description Coding over Multiple Paths, Vu Thanh Nguyen, Ee-Chien Chang, Wei Tsang Ooi, ICME 2004, Taipei, Taiwan, June 2004. [pdf]
2003
  • Packet Allocation for Layered Media Transmission with Path Diversity, Vu Thanh Nguyen, Wei Tsang Ooi, Ee-Chien Chang, Technical Report TR21/03, School of Computing, National University of Singapore, 2003. [pdf]