Adaptive playout scheduling for multi-stream voice over IP networks

Packet delay and loss are two essential problems to real-time voice transmission over IP networks. In the proposed system, multiple redundant descriptions of the speech are transmitted to take advantage of largely uncorrelated delay and loss characteristics on independent network paths. Adaptive playout scheduling of multiple voice streams is then formulated as a constrained optimization problem leading to a better balance between end-to-end delay and packet loss. For proper reconstruction of continuous speech, we also develop a packet-based time-scale modification algorithm based on sinusoidal representation of the speech production mechanism. Experimental results indicate that the proposed adaptive multi-stream playout scheduling technique improves the delay-loss tradeoff as well as speech reconstruction quality.