In this paper, a novel transcoding algorithm specially related to codebook gain conversion is proposed between AMR-NB at 7.95kb/s and G.729a. It can bypass the gain predictive process and directly convert codebook gain parameters. Additionally, the new gain parameter conversion method can be extended to the other rate modes of AMR-NB while transcoding with G.729a. The experimental results show that the quality of transcoded speech using the proposed algorithm is improved greatly and the computational complexity is reduced by 85% compared with DTE (Decode then Encode) method. A 5ms look-ahead delay is avoided as well.
Bibliographic reference. Xu, Hao / Bao, Changchun (2008): "A novel transcoding algorithm between 3GPP AMR-NB (7.95kbit/s) and ITU-t g.729a (8kbit/s)", In INTERSPEECH-2008, 49-52.