Multimedia Group synchronization based in standard protocols

Most of actual multimedia tools use RTP/RTCP for inter-stream synchronization, but not for group synchronization. A new proposal of modification of RTCP packets to provide a sender-based method for synchronization of a group of receivers is described and evaluated both objectively and subjectively. The solution takes advantage of the feedback RR RTCP messages and the malleability of RTP/RTCP to provide the information required by the synchronization approach, defining a few new APP RTCP packets useful for synchronization purpose. This modification hardly increases the workload of the network and helps to avoid the asynchronies, between receivers (distributed) and between streams (locally), exceeding the limits, in accordance with the related literature.