Data communication system, data transmission apparatus, data reception apparatus, data communication method, and computer program

A data transmission apparatus for transmitting streaming data, comprising:

• a packet transmission processing unit for transmitting a plurality of data packets containing transmission data;
• and
• a retransmission control unit for extracting at least one data packet to be retransmitted according to a retransmission request received from a data reception apparatus, wherein said data transmission apparatus executes duplicate retransmission of at least one designated data packet in accordance with data of a designated count of duplicate retransmission designated in a retransmission-request message packet received from said data reception apparatus.

A data transmission apparatus for transmitting streaming data, comprising:

• a packet transmission processing unit for transmitting a plurality of data packets containing transmission data;
• and
• a retransmission control unit for extracting at least one data packet to be retransmitted according to a retransmission request received from a data reception apparatus, wherein said retransmission control unit extracts at least one packet to be retransmitted based on at least one of sequence-number designation data designating at least one data packet and timestamp designation data for at least one packet, and an option value, included in a retransmission-request message packet received from said data reception apparatus.

A data reception apparatus for receiving streaming data, comprising:

• a packet reception processing unit for receiving a plurality of data packets transmitted from a data transmission apparatus;
• and
• a retransmission-request processing control unit for determining whether to transmit a retransmission-request message packet that serves as a data-packet retransmission request to said data transmission apparatus, based on detection of at least one of a lost packet and an error in the plurality of data packets transmitted from said data transmission apparatus, wherein said retransmission-request processing control unit determines whether one or more retransmission data packets associated with the retransmission request can be received in time for processing relating to playing of data contained in the one or more retransmission data packets, and determines to transmit the retransmission request on condition that the one or more retransmission data packets can be received in time.

A computer readable medium storing a computer readable program for receiving streaming data, said computer readable program comprising the steps of:

• a packet reception processing step of receiving a plurality of data packets transmitted from a data transmission apparatus;
• and
• a retransmission-request processing control step of determining whether to transmit a retransmission-request message packet that serves as a data-packet retransmission request to said data transmission apparatus, based on detection of at least one of a lost packet and an error in the plurality of data packets transmitted from said data transmission apparatus, wherein said retransmission-request processing control step includes a step of determining whether one or more retransmission data packets associated with the retransmission request can be received in time for processing relating to playing of data contained in the one or more retransmission data packets, and determining that the retransmission request be transmitted on condition that the one or more retransmission data packets can be received in time.