Adaptive multimedia synchronization in a teleconference system

In this paper, we present an adaptive buffering scheme for implementing int ra-stream and inter-stream synchronization in real-time multimedia applicat ions. The essence of the proposed scheme is to dynamically enforce equalize d delays to incoming media streams, in order to piece-wise smooth the netwo rk delay variations and to synchronize the streams at the sink. An adaptive control mechanism based on an event-counting algorithm is employed to cali brate the PlayOut Clocks (POCs), which manages the presentations of multime dia data. The algorithm does not rely on globally synchronized clock and ma kes minimal assumption on underlying network delay distribution. Also, the user defined quality of service (QoS) specifications can be directly incorp orated into the design parameters of the synchronization algorithm. The pro posed synchronization scheme has been experimentally implemented in a telec onference system which consists of separately controllable audio, video, an d data channels. The modular structure of the synchronization control provi des the flexibility to maintain an arbitrary synchronization group in conju nction with a distributed conference management scheme. This paper also sho ws the experimental results of the test implementation and the suitability of the proposed scheme with respect to the multimedia traffic across an FDD I/Ethernet network.