Patent ID: 7496040

Claim:
An apparatus for measuring a roundtrip delay time associated with communication of multimedia data, the apparatus comprising: a video encoder for encoding multimedia data to produce encoded multimedia data; a transmission rate controller for controlling transmission rate of the encoded multimedia data according to a transmission rate; a first sending/receiving unit for sending the multimedia data via a first channel; a roundtrip delay time (RTT) measuring unit for measuring an instant roundtrip delay time using a receiver report (RR) packet received by the first sending/receiving unit; a moving average calculating unit for calculating a moving average roundtrip delay time using the measured instant roundtrip delay time; and a transmission rate estimating unit for estimating the transmission rate using the moving average roundtrip delay time and providing the estimated transmission rate to the transmission rate controller, wherein the moving average calculating unit measures the moving average roundtrip delay time according to: RTT ( t )=(1− j )· RTT ( t− 1)+ j·RTT new wherein, the RTT new denotes a new instant roundtrip delay time, the RTT(t) denotes a roundtrip delay time value obtained by calculating the RTT new and thereafter calculating the moving average of the RTT new at time t, and the j denotes a weight for determining an adaptation speed with respect to the network state.