Adaptive multimedia synchronization in a teleconference system

We present an adaptive buffering scheme for implementing intra-stream and inter-stream synchronization in real-time multimedia applications. The essence of the proposed scheme is to dynamically enforce buffering delays to the incoming media streams in order to piecewisely smooth the end-to-end delay variation. A control mechanism based on an efficient event-counting algorithm is employed to calibrate the playout clocks (POCs), which manage the presentations of multimedia streams. The proposed synchronization algorithm is simple, robust, and does not rely on the globally synchronized clock. It virtually works with any network delay distribution. The proposed synchronization scheme has been implemented in our experimental teleconference system which consists of separately controllable audio, video, and data channels. The modular structure of synchronization control provides the flexibility to maintain an arbitrary synchronization group. This paper also shows the experimental results with respect to the multimedia traffic across an FDDI/Ethernet network.