Audio Quality and Acoustic Echo Issues for VOIP on Portable Devices

Abstract

Abstract-The control of the overall quality of service for VOIP applications depends for sure on features and capabilities of the network layer but at the same time, and especially in the case of low-resource, portable devices, it relies on smart flexible signal processing and control tools that allow tuning the usage of computational resources to obtain the best possible quality for a given system. Audio signal I/O (acquisition and rendering), packet loss concealment and acoustic echo detection and suppression play a fundamental role, since good algorithms are rather demanding for calculations but their presence is often necessary to compensate low-cost, average-quality platforms and interfaces. Some measures and remarks on these platforms and interfaces are presented in this paper, together with a set of implemented solutions providing a remarkable improvement in the mean opinion score of a typical VOIP conversation for different families of PDAs and Smartphones.

Adaptive Parallelism Exploitation under Physical and Real-Time Constraints for Resilient Systems

“…The network impulse response has a typical length of 64 to 128ms [Lin et al 2008], whereas the acoustic impulse response has a typical length of ∼300ms [Zoia et al 2007]. Considering a long response impulse such as acoustic echo, the adaptive filter requires a higher number of taps, thus demanding a higher computation effort.…”