Video bridging based on H.261 standard

Multi-point ISDN videoconferencing with video bridging in network-based servers represents a viable new network service. The paper presents a detailed technical analysis of a continuous presence video bridge using the H.261 video coding standard. The authors first compare the pros and cons of coded domain versus pel domain video bridges. The architecture and the required operations of a coded domain bridge using H.261 are then investigated. They derive the bounds of the bridge delay and the required buffer size for the implementation of the bridge. The delay and the buffer occupancy of the video bridge depend on the order, complexity, and the bit-distribution of the input video sources. To investigate a typical case, the authors simulate the delay and the buffer occupancy of a video bridge. They also provide a heuristic method to estimate the delay in a typical case. Several techniques are discussed to minimize the bridge delay and the buffer size. Finally, they simulate intra slice coding and show that the delay and the buffer size can be reduced significantly using this technique