Subrate multimedia data transmission control system

A real time multiplexed bit allocation in a 8 kbps frame unit of a transmission frame having a repeating cycle of 8khz is realised in a variable fashion such that an automatic matching of a transmission frame is achieved at an initiation of a transmission and that error check bits of the error correction code are contained in a transmission frame with a satisfactory matching. In addition, the multiframe configuration enables it to handle in an integrated fashion the synchronizations of the voice data frame, the error correction frame, and the video data packet, which as a result minimizes the size of the buffer memories disposed to send and/or to receive moving pictures and which enables the transmission speed smoothing operation to be accomplished in a simple configuration through an easy control.