This paper proposes a media synchronization mechanism for live media streams. The mechanism can also handle stored media streams by changing parameter values. The authors have implemented the mechanism on a lip-synch experimental system. Live video and voice streams input at a source workstation are transferred, and then they are synchronized and output at a destination workstation. This paper also evaluates the system performance such as mean square error of synchronization, average output rate, and average delay.

This paper proposes a scheme for synchronization of stored video and audio streams in PHS. A video stream of H. 263 is transmitted over a PHS channel with ARQ control, while an audio stream of 32 kbit/s ADPCM is sent on another channel without any control. In order to preserve the temporal constraints within the video stream as well as the relationship between the video and audio streams, we adopt a new control scheme which modifies the target output time according to the amount of video data in the receive-buffer. Through simulation we assess the characteristics of this scheme in both random and burst error environments and confirm the effectiveness of the scheme.

This paper reports experimental results of a media synchronization mechanism which was proposed by the authors, focusing on the graceful recovery scheme. The proposed method consists of intra-stream and inter-stream synchronization mechanisms. The inter-stream synchronization control is performed after the intra-stream synchronization control over each media unit (MU) such as a video frame. Then, whether the intra-stream synchronization is still maintained or not is checked. In the experimental system, video and voice stored in a source workstation are transferred to a destination workstation via an FDDI network, and then they are synchronized and outputted at the destination (i.e., lip-synch). At the transmission of each MU, we simulate network delay jitters by generating a pseudo-delay which is exponentially distributed. Using the system, we have confirmed the validity of the mechanism. We also clarify how to set the threshold and parameter values defined in the mechanism by evaluating mean square error and average MU rate or by subjective assessment. Furthermore, we demonstrate that the intra-stream synchronization control for each streams in addition to the inter-stream control is necessary for high quality synchronization.