Title :
Variable-dimension vector quantization of speech spectra for low-rate vocoders
Author :
Das, Amitava ; Rao, Ajit V. ; Gersho, Allen
Author_Institution :
Center for Inf. Process. Res., California Univ., Santa Barbara, CA, USA
Abstract :
Optimal vector quantization of variable-dimension vectors in principle is feasible by using a set of fixed dimension VQ codebooks. However, for typical applications, such a multi-codebook approach demands a grossly excessive and impractical storage and computational complexity. Efficient quantization of such variable-dimension spectral shape vectors is the most challenging and difficult encoding task required in an important family of low bit-rate vocoders. The authors introduce a simple and effective formulation of variable-dimension vector quantization (VDVQ) which quantizes variable-dimension vectors using a single universal codebook having fixed dimension yet covering the entire range of input vector dimensions under consideration. This VDVQ technique is applied to quantize variable-dimension spectral shape vectors leading to a high quality speech coder at the low bit-rate of 2.5 kb/s. The combination of a universal spectral codebook and structured VQ reduces storage and computational complexity, yet delivers a high quantization efficiency and enhanced perceptual quality of the coded speech
Keywords :
spectral analysis; speech coding; speech intelligibility; vector quantisation; vocoders; voice communication; VDVQ; coded speech quality; computational complexity; encoding; high quality speech coder; input vector dimensions; low-rate vocoders; optimal VQ; perceptual quality; quantization efficiency; speech spectra; structured VQ; universal spectral codebook; variable-dimension spectral shape vectors; variable-dimension vector quantization; Application software; Computational complexity; Encoding; Information processing; Random variables; Spectral shape; Speech enhancement; Speech processing; Vector quantization; Vocoders;
Conference_Titel :
Data Compression Conference, 1994. DCC '94. Proceedings
Conference_Location :
Snowbird, UT
Print_ISBN :
0-8186-5637-9
DOI :
10.1109/DCC.1994.305949