Signal processing device, signal processing program and communication system

摘要

There is provided a signal processing device including: a packet receiving means for receiving a packet from a transmitting communication device; and a packet processing means for transmitting the received packet received by the packet receiving means, simply as received or after processing by a packet converting means, to a receiving communication device that is a destination of the packet, wherein when a communication session between a first transmitting communication device and the receiving communication device is established and the session is shifted to have a connection between a second transmitting communication device and the receiving communication device, the packet converting means converts the received packet received from the second transmitting communication device so as to maintain a consecutiveness related to a content of packets to be transmitted to the receiving communication device.

主权项

1. A signal processing device comprising:
a packet receiving means for receiving packets from IP communication terminals; and a signal processing means for transmitting information carried by packets received by the packet receiving means to other IP communication terminals, wherein the signal processing means comprises:
means for establishing a communication session between a first one of the IP communication terminals and a second one of the IP communication terminals during a first time interval, andmeans for permitting the session to be shifted so as to have a connection between the first one of the IP communication terminals and a third one of the IP communication terminals during a second time interval that begins following an end of the first time interval, and wherein the means for permitting includes packet converting means for converting packets received by the packet receiving means from the third one of the IP communication terminals during the second time interval so as to maintain a consecutiveness of RTP sequence numbers and time stamps with packets received by the packet receiving means from the first one of the IP communication terminals during the first time interval and so as to maintain consistency of synchronization source identifiers included in RTP headers of RTP packets to be transmitted to the first one of the IP communication terminals during the first and second time intervals, the packet converting means determining sequence numbers Nseq of packets to be transmitted to the first one of the IP communication terminals during the second time interval in accordance with the equation Nseq=SEQ−Rseq+Sseq, where SEQ represents sequence numbers of packets received by the signal processing means from the third one of the IP communication terminals during the second time interval, Rseq represents the sequence number of the first packet received by the signal processing means from the third one of the IP terminals during the second time period, and Sseq represents the sum of a predetermined number plus the sequence number of the last packet received by the signal processing means from the second one of the IP communication terminals during the first time period.