Synchronization Quality Enhancement in 3G-324M Video Telephony

Media synchronization is an important issue to be solved in order to achieve satisfactory video communication quality in 3G-324M mobile video telephony. This paper analyzes weaknesses of existing solutions and telephony protocols from the aspect of synchronization, and proposes an enhanced mobile media synchronization scheme. The scheme consists of dynamic multiplex code selection (DMCS) and a frame-to-frame (F2F) adaptive playout strategy (F2F-APS). The DMCS is to construct a plurality of multiplex codes for one channel and select an optimal multiplex code from those based on the send-buffer occupancy and the F2F-APS is an adaptive playout strategy based on frame-to-frame delay at the receiver. In order to evaluate the method, we implemented it in the control application of a real 3G mobile phone and measured the media synchronization error. The experimental results show that the synchronization inconsistency between audio and video streams can be decreased by more than 10% compared to a conventional scheme in a highly erroneous environment.