Improvement issues on transcoding algorithms: for the flexible usage to the various pairs of speech codec
Jin-Kyu Choi, Chang-Heon Lee, K. Hong-Goo, Young-Cheol Park, Dae Hee Youn · 2004
The paper describes important issues on transcoding between different speech codecs by considering the paradigms of source and target coders. Conventional transcoding algorithms on LSP, pitch and adaptive/fixed codebook conversion are refined with regard to the structure of the coders. In addition, a new perceptual weighting filter, that plays a role in the post-filter and perceptual weighting filter together, is proposed to improve the performance further. The performance of the proposed algorithms is verified in a step-by-step manner with examples of transcoding between AMR, G.723.1 and G.729. By applying the proposed algorithm to the transcoders, the complexity is reduced by about 20-76.88% and quality is also improved compared to conventional approaches.