Optimal Adaptive Voice Smoother with Lagrangian Multiplier Method for VoIP Service

VoIPs, emerging technologies, offer high-quality, real-time voice services over IP-based broadband networks. Perceived voice quality is a key metric for VoIP applications that is mainly affected by IP network impairments such as delay, jitter, and packet loss. Playout buffers at the receiving end can compensate for the effects of jitter based on a tradeoff between delay and loss. Adaptive smoothing algorithms are capable of dynamically adjusting the smoothing size by introducing a variable delay based on the network parameters to avoid the quality decay problem. This paper introduces an efficient and feasible perceived quality method for buffer optimization to achieve the best voice quality. This work formulates an online loss model that incorporates buffer sizes and applies the Lagrangian Multiplier approach to optimize the delay-loss problem. Distinct from the other optimal smoothers, the proposed optimal smoother, suitable for most codecs, carries the lowest complexity. Simulation experiments confirm that the proposed adaptive smoother achieves significant improvement in the voice quality. Key-Words: Adaptive voice smoother, VoIP, buffer re-synchronization, delay/loss trade off