A Novel Transcoding Technique between EVRC and G.729A for Mobile Multimedia Devices

In this paper, we propose a novel transcoding technique between enhanced variable rate codec (EVRC) and G.729A for mobile multimedia devices. The simplest way to communicate between heterogeneous speech networks is the cascade connection of two different codecs, called tandem coding. However, tandem coding not only has high computational loads, but also makes long delay. These problems can be solved by the effective transcoding algorithm using line spectral pair (LSP) and pitch delay conversion in speech codec. The proposed algorithm consists of LSP conversion, pitch delay conversion and algorithm for delay reduction. Experimental results show the proposed algorithm has lower computational complexity, shorter algorithm delay, and similar speech quality in comparison of the tandem algorithm.