Patent ID: 7061863

Claim:
A data communication system having a data sending terminal which sends data to a network and changes data quality of the data sent to the network according to the network load and a receiving terminal which receive the data from the network and accumulates the received data, said system comprising: at the data receiving terminal (a) a received-data quality discriminating section for discriminating whether or not the received data from the data sending terminal satisfies a predetermined accumulation quality; (b) an alternative-data sending requesting section for, if the received data of a particular time section does not satisfy the accumulation quality caused by the data sending terminal changing of the data quality as the result of discrimination by said received-data quality discriminating section, requesting the data sending terminal to send alternative data having a data quality higher than the data quality of the received data and satisfying the accumulation quality for the received data of the particular time section; (c) a received-data accumulating section for accumulating the received data as judged satisfying the accumulation quality by said received-data quality discriminating section, and the alternative data as sent from the data sending terminal in response to the request by said alternative-data sending requesting section; at the data sending terminal (d) an alternative-data sending request receiving section for receiving, from said alternative-data sending requesting section of the data receiving terminal, the request for sending of alternative data satisfying the accumulation quality; (e) a sending-data accumulating section for accumulating data to be sent to the data receiving terminal as alternative data to be sent to the data receiving terminal in response to the sending request from the data receiving terminal; and (f) an alternative-data sending section for, upon receipt of the sending request by said alternative-data sending request receiving section, obtaining alternative data satisfying the accumulation quality from accumulated contents of said sending-data accumulating section and then sending the obtained alternative data to the data receiving terminal.