A study of perceptual VoIP quality evaluation with thai users and codec selection using voice quality - Bandwidth tradeoff analysis

Perceptual VoIP quality is an issue for VoIP applications/services because VoIP applications require real-time support. Not only network factors (e.g. packet loss, packet delay and jitter) but also codec selection that affects VoIP quality. Therefore, this study has been conducted, focusing on the perceptual VoIP quality and codec selection. This paper presents a study of the perception of native Thai subjects to the popular codecs, G.711, G.722, G.723.1 and G.729 using ACR listening opinion tests and conversation opinion tests. It has been found that native Thai users ranked VoIP quality from G.723.1 at 5.3 kbps as the worst, and no statistically significant difference from G.729 (8 kbps), G.711 (64 kbps) and G.722 (64 kbps). Then, the paper proposes voice quality - bandwidth tradeoff analysis approach for codec selection, based on perceptual VoIP quality and bandwidth consumption of voice-payload of codecs. It has been found from this approach that G.729 at 8 kbps is the best choice for VoIP codec selection for Thai users in Thailand, compared to the other codecs.