Patent ID: 7916653

Claim:
Apparatus for determining a round-trip delay of a media stream in a conferencing or telephony system comprising: a speaker; a microphone; and a processing unit coupled with the speaker and the microphone, the processing unit being operable to output, via the speaker, a first audio waveform having a predefined duration for reception by a first endpoint device of the conferencing or telephony system, the first endpoint device encoding the first audio waveform into one or more data packets for transmission over a packet-based network to a second endpoint device of the conferencing or telephony system, the second endpoint device playing out the first audio waveform to another apparatus that responds by producing a second audio waveform, the first and second audio waveforms each having unambiguous characteristics that resemble speech, the second audio waveform being emitted after a delay of a fixed period of time, the second audio waveform being encoded by the second endpoint device and sent over the network to the first endpoint device, the first endpoint device playing out the second audio waveform, the microphone capturing the second audio waveform, the processing unit being further operable to calculate the round-trip delay across the packet-based network based on a time period measured from the output of the first audio waveform to the capturing of the second audio waveform without the use of timestamps, the processing unit subtracting the fixed period of time from the time period in calculating the round-trip delay, wherein the processing unit rejects any audio waveforms received during a duration substantially equal to the fixed period of time after the first audio waveform is outputted.