Recent interest in supporting packet-audio applications over widearea networks has been fueled by the availability of low-cost,toll-quality workstation audio and the demonstration that limitedamounts of interactive audio can be supported by today's Internet. Insuch applications, received audio packets are buffered, and theirplayout delayed at the destination host in order to compensate for thevariable network delays. The authors investigate the performance of fourdifferent algorithms for adaptively adjusting the playout delay of audiopackets in an interactive packet-audio terminal application, in the faceof such varying network delays. They evaluate the playout algorithmsusing experimentally-obtained delay measurements of audio trafficbetween several different Internet sites. Their results indicate that anadaptive algorithm which explicitly adjusts to the sharp, spike-likeincreases in packet delay which were observed in the traces can achievea lower rate of lost packets for both a given average playout delay anda given maximum buffer size
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