|
|
|
| Main |
| Publications |
| Statistics |
| People |
| Research |
| Teaching |
| Press Coverage |
|
|
I. Streaming Media |
| HYDRA - High-speed Data Recording Architecture |
|
Presently, digital continuous media (CM) are well established as an integral part of many applications. In recent years, a considerable amount of research has focused on the efficient retrieval of such media. Scant attention has been paid to servers that can record such streams in real time. However, the current technological trends are such that more and more sensor devices (e.g., cameras) can directly produce digital data streams. Furthermore, some of these new devices are network-capable either via wired (SDI, Firewire) or wireless (Bluetooth, IEEE 802.11x) connections. Hence, the need arises to capture and store these streams with an efficient data stream recorder that can handle both recording and playback of many streams simultaneously and provide a central repository for all data.  Our research activities are focusing on the design and implementation of a High-performance Data Recording Architecture (HYDRA). The goal of HYDRA is to improve current and enable new applications by acting as an efficient media stream coordinator that manages the transmission, recording, and playback of many different data streams simultaneously. The objective of HYDRA is to use a unified paradigm that integrates multi-stream recording, retrieval and control in a synergetic manner. HYDRA aims to provide the same services for all media, independent of their bandwidth requirements, resolution or modality. One of the applications that we are exploring for this technology is a Distributed Immersive Performance where musicians and audiences are geographically disbursed in different locations. The HYDRA architecture is based on a scalable cluster design. Each cluster node is a off-the-shelf personal computer with attached storage devices and, for example, a Fast Ethernet connection. The HYDRA server software manages the storage and network resources to provide real-time service to the various clients that are requesting media streams. The design goals of our architecture can be summarized as follows:
We have performed experiments across both LAN and WAN environments. Our most recent tests were conducted via a two-way, trans-pacific Internet2 link between the East West Center at the University of Hawaii in Honolulu, and the USC campus in Los Angeles, CA. People Involved
More Information
|
| ACTIVE AudioPeer - Peer-to-Peer Streaming |
There is evidence from learning and psychology research that indicates memory is enhanced by spatial associations. Such spatial information is lost with current telephone-based teleconferencing, which makes it difficult to hold audio teleconferences with large numbers of people. Since classroom discussions can involve large numbers of students,it is currently difficult to make practical use of audio teleconferencing in courses with large enrolments. We propose to address this problem by developing a prototype Multiuser Audio Chat System with the features of rendering the source of users initially to several predetermined spatially arranged positions, as well as generating and archiving a searchable transcript of each session. This will make it possible for remote learners to participate more actively in on-line discussions, and give them more of a sense of being present in the discussion session, just as graphics-based virtual reality technology gives users the illusion of being present in a virtual scene. This same technology can provide students with the ability to "go back in time" to query and recall earlier discussion sessions. The multiuser audio chat system involves numerous technical challenges that need to be addressed to build such an application. The number of participants in a chat session may be several dozens, with each student needing to hear and possibly talk to any other person in the session. Hence, one of the primary concerns is an efficient interconnection topology and architecture. An immediate first approach would be to connect each participant to a central server that merges incoming audio streams and then distributes the final mixed result to every listener that is connected. The advantage of such a star layout is that the sessions can be centrally managed and the delay for the sound streams to be relayed by the server depends mostly on the distance of the users from the server. The disadvantages of this architecture are that the central server requires a large amount of resources (for example memory and network bandwidth) that is proportional to the number of participants. Furthermore, the server can easily become a bottleneck and also is a single point of failure. Therefore, we plan to develop and implement a more distributed peer architecture where a newly joining user may be connecting to one of her peers who is already participating in an ongoing audio chat session. We envision that some central control is still necessary to manage the session (for example for floor control, i.e., who should be allowed to speak and at what time). However, the network resources that are required at the server side for this architecture will be greatly reduced. One of the challenges with a distributed architecture is that the end-to-end audio latency may be more variable. From existing research we know that for an interactive conversation the delay from the microphone input through the transmission to the audio speaker output should not exceed 100 to 200 milliseconds for a natural conversation. If these limits are surpassed then the delay becomes distracting. The audio chat system will automatically select a peer connection that will enable audio transmissions to take place within these given limits. People Involved
|
|
II. Web Services and Database Integration |
| GIME - Geotechnical Information Exchange |
 The Geotechnical Information Exchange ITR Project is an NSF sponsored research collaboration project (Jean-Pierre Bardet, PI; Roger Zimmermann, Co-PI) aimed at supplying ITR solutions for the exchange and utilization of geotechnical information. Nowadays Information Technologies (IT) unleash new powerful opportunities for collecting, exchanging, and utilizing geotechnical information, which should be explored for the sake of our civil infrastructures. Our research creates ITR methods for resolving major issues associated with the collection, exchange and utilization of geotechnical information. The research integrates different IT methods to produce a comprehensive and complete description and utilization of geotechnical information starting from the data generation in the laboratory and field to its end usage by engineers and planners involved in civil infrastructure systems. Objectives of the research:
People Involved
Project Web Site
Additional Information
|
|
III. Previous Projects |
| YIMA - Streaming Media Architecture |
|
The research activities at the USC Data Management Research Lab and the Information Laboratory during the past several years have resulted in the design, implementation and evaluation of Yima, a scalable real-time streaming architecture that enables applications such as video-on-demand and distance learning on a large scale. Yima incorporates lessons learned from first generation research prototypes and it also complies with industry standards in content format (e.g., MPEG-2, MPEG-4) and communication protocols (RTP/RTSP). The Yima server is based on a scalable cluster design. Each cluster node is a off-the-shelf personal computer with attached storage devices and, for example, a Fast Ethernet connection. The Yima server software manages the storage and network resources to provide real-time service to the various clients that are requesting media streams. The Yima clients run on either Windows or Linux and may utilize a hardware or software decoder to display media streams. We have implemented a number of different clients that support a variety of display bandwidths from less than 1 Mb/s to more than 45 Mb/s. Furthermore, Yima is the basis of the Remote Media Immersion (RMI) project. RMI is a testbed that integrates many of the technologies that are the result of multiple research efforts. The goal of the RMI is to reproduce the complete aural and visual ambience of an environment that includes people and other real and virtual elements. We have performed experiments across both LAN and WAN environments. Recent tests were conducted via a trans-continental SUPERNET link from the Information Science Institute (ISI East) at Arlington, VA, and also via Internet2 to the USC campus in Los Angeles, CA. See also the SUPERNET Next Generation Internet (NGI) Experiments web site. The YIMA project the foundation for our current work on the HYDRA system (see above). People Involved
Additional Information
|
|
Maintained by
Roger Zimmermann |