Abstract: A multimedia conferencing system has a plurality of remote user terminals, each of which may be different from any other, and each of which may communicate to a central processing hub using different communications protocols. The central processing hub receives, processes, and sends video and audio data from and to the plurality of remote users, and comprises a media bus for handling video and audio data signals, a packet bus for handling data and control signals, a shelf controller card which issues control messages in keeping with incoming management signals, a bus controller card which provides clock and bus arbitration signals, at least one media processor card for processing video and audio signals, and video encoding means for receiving video data from the one or more media processor cards and delivering video data signals to the packet bus. Video and audio data signals may be received by or delivered from any of the at least one media processor card and the at least one physical interface card.