In this paper we propose a new technique to quantize the spectral information in an Algebraic Code-Excited Linear Prediction (ACELP) wideband codec. The Voicing-Based Vector Quantization (VBVQ) presented in this paper, optimizes the search of the optimum vector while reducing the codebook entries by almost one third. In the VBVQ training phase, three codebooks are individually designed for voiced, unvoiced and transition speech. The proposed technique reduces the processing delay since it restricts the quantization of an input vector to only one of the three codebooks. For each speech frame, one codebook is selected based on the interframe correlation of the spectral information.
The VBVQ was successfully implemented in an ACELP wideband coder. The objective and subjective performance are superior to that of the combination of the split vector quantization and multistage vector quantization after using the same database for training and testing.
Bibliographic reference. Guerchi, Driss / Rabie, Tamer / Louzi, Abdelrhani (2007): "Voicing-based codebook in low-rate wideband CELP coding", In INTERSPEECH-2007, 2505-2508.