Superwideband extension for AMR-WB using conditional codebooks

In this paper, the conditional codebook mapping (CCM) method is proposed for super-wideband extension (SWB) of speech signals to achieve a wider bandwidth up to 12.8 kHz. As we know, the performance of bandwidth extension by codebook mapping (CM) is restricted by the codebook size. The proposed CCM-based BWE method reduces the restriction while introducing a conditional codebook and is applied in AMR-WB at 19.85 kbps. Both the Objective test results in the term of Log-spectral distortion (LSD) and Perceptual Evaluation of Speech Quality (PESQ) and the subjective test results show that the CCM-based SWB extension method achieves higher speech quality compared with the CM method.