Adaptive playout scheduling using time-scale modification in packet voice communications

A new receiver-based playout scheduling scheme is proposed, which estimates the network delay from past statistics and adaptively adjusts the playout time of the voice packets. In contrast to previous work, the adjustment is not only performed in between talkspurts, but also within the talkspurts in a highly dynamic way. Proper reconstruction of continuous output speech is achieved by scaling individual voice packets using a time-scale modification technique which modifies the rate of playout while preserving voice pitch. Subjective listening tests show that this operation does not impair the audio quality. Simulation results based on Internet measurement indicate that buffering delay and loss rate can be significantly reduced by adaptive scheduling.