Real-time distributed multi-party/multi-stream systems are becoming more popular in many areas such as 3D tele-immersion, multi-camera conferencing and security surveillance. However, the construction of such systems in large scale is impeded by the huge demand of computing and networking resources and the lack of a simple yet powerful networking model to handle interconnection, scalability and quality of service (QoS) guarantees. We make two main contributions in the paper: (1) we propose a novel generalized ViewCast model for multiparty/multi-stream video-mediated systems that fills the gap between high-level user interest and low level per-stream management, and (2) we demonstrate the ViewCast model by applying it to the multi-party 3D Tele-Immersive (3DTI) collaboration among geographically dispersed users. More specifically, we show how the ViewCast model is used in supporting stream data dissemination, coordination and QoS management among multiple 3D tele-immersive environments. We present our experimental results in both real implementation and simulation to show that our ViewCast-based solution achieves high efficiency, scalability, and quality in supporting multi-party 3DTI collaboration.

Tele-immersive systems can improve productivity and aid communication by allowing distributed parties to exchange information via a shared immersive experience. The TEEVE research project at the University of Illinois at Urbana-Champaign and the University of California at Berkeley seeks to foster the development and use of tele-immersive environments by a holistic integration of existing components that capture, transmit, and render three-dimensional (3D) scenes in real time to convey a sense of immersive space. However, the transmission of 3D video poses significant challenges. First, it is bandwidth-intensive, as it requires the transmission of multiple large-volume 3D video streams. Second, existing schemes for 2D color video compression such as MPEG, JPEG, and H.263 cannot be applied directly because the 3D video data contains depth as well as color information. Our goal is to explore from a different angle of the 3D compression space with factors including complexity, compression ratio, quality, and real-time performance. To investigate these trade-offs, we present and evaluate two simple 3D compression schemes. For the first scheme, we use color reduction to compress the color information, which we then compress along with the depth information using zlib. For the second scheme, we use motion JPEG to compress the color information and run-length encoding followed by Huffman coding to compress the depth information. We apply both schemes to 3D videos captured from a real tele-immersive environment. Our experimental results show that: (1) the compressed data preserves enough information to communicate the 3D images effectively (min. PSNR > 40) and (2) even without inter-frame motion estimation, very high compression ratios (avg. > 15) are achievable at speeds suffi...

We consider the problem of flow coordination in distributed multimedia applications. Most transport-level protocols are designed to operate independently and lack mechanisms for sharing information with other flows and coordinating data transport in various ways. This limitation becomes problematic in distributed applications that employ numerous flows between two computing clusters sharing the same intermediary forwarding path across the Internet. In this paper, we propose an open architecture that supports the sharing of network state information, peer flow information, and application-specific information. Called simply the Coordination Protocol (CP), the scheme facilitates coordination of network resource usage across flows belonging to the same application, as well as aiding other types of coordination. The effectiveness of our approach is illustrated in the context of multi-streaming in 3D tele-immersion where consistency of network information across flows both greatly improves frame transport synchrony and minimizes buffering delay.

3D tele-immersion (3DTI) has recently emerged as a new way of video-mediated collaboration across the Internet. Unlike conventional 2D video-conferencing systems, it can immerse remote users into a shared 3D virtual space so that they can interact or collaborate “virtually”. However, most existing 3DTI systems can support only two sites of collaboration, due to the huge demand of networking resources and the lack of a simple yet efficient data dissemination model. In this paper, we propose a general publish-subscribe model for multi-site 3DTI systems, which efficiently utilizes limited network resources by leveraging user interest. We focus on the overlay construction problem in the publish-subscribe model by exploring a spectrum of heuristic algorithms for data dissemination. With extensive simulation, we identify the advantages of a simple randomized algorithm. We propose optimization to further improve the randomized algorithm by exploiting semantic correlation. Experimental results demonstrate that we can achieve an improvement by a factor of five. 1

Urbana, Illinoissenting the user interest in the application layer. The design of the management framework revolves around the concept of view-aware multi-stream coordination, which leverages the central role of view semantics in 3D free-viewpoint video systems. Second, in the stream differentiation layer we present the design of view to stream mapping, where a subset of relevant streams are selected based on the relative importance of each stream to the current view. Conventional streaming controllers focus on a fixed set of streams specified by the application. Different from all the others, in our management framework the application layer only specifies the view information while the underlying controller dynamically determines the set of streams to be managed. Third, in the stream coordination layer we present two designs applicable in different situations. In the case of end-to-end 3DTI communication, a learning-based controller is embedded which provides bandwidth allocation for relevant streams. In the case of multi-party 3DTI communication, we propose a novel ViewCast protocol to coordinate the multi-stream content dissemination upon an end-system overlay network. Finally, we embed 3DTI session management in the framework which facilitates