A data communications system is provided to dynamically change the error processing between an ARQ function and an FEC function in accordance with the network status, thus enabling high-quality data playback. In packet transmission, error correction control is performed on the basis of the network status monitored by a network monitoring unit. The error control mode is switched between FEC-based error control and ARQ-based error control (retransmission request processing) in accordance with packet loss or error occurrence on the network, and packet transmission is performed. If the RTT is short, error correction based on ARQ is selected. If the RTT is long, error correction not based on ARQ but on FEC is selected. Such dynamic error correction control is achieved.