Enhanced multiband excitation coding of speech at 2.4 Kb/s with discrete all-pole spectral modeling
Amitava Das, A.V. Rao, A. Gersho · 2002
This paper presents a high quality, low bit rate speech coder which applies an effective spectral modeling technique called discrete all-pole (DAP) modeling to efficiently represent speech spectra. The technique provides a fixed-dimension representation of the (pitch-dependent) variable dimension spectral shape vectors which arise in harmonic coders. Consequently, the spectral shapes are quantized more efficiently than with the usual linear prediction modeling, leading to better speech quality. We present a 2.4 kb/s speech coder, based on the multiband excitation (MBE) model and DAP modeling of the speech spectra, which delivers speech quality comparable to two standard higher rate coders: the 4.8 kb/s U.S. Federal Standard 1016 CELP coder and the 4.15 kb/s IMBE coder, adopted as the INMARSAT-M standard for satellite voice communications.