Multi-band vector excitation coding of speech at 4.8 kbps

A speech coder is presented which combines vector excitation coding (VXC) with frequency-domain representations so as to obtain a high-quality efficient scheme at 4.8 kb/s based on the use of different coding strategies and bit allocations for different frames of speech and different frequency bands. Attention is focused on the representation of voiced sounds and on multiband procedures for representing the short-time Fourier transform. The proposed scheme starts with a phonetically based frame segmentation. Multiband long-term prediction is included only when necessary, and random excitation in voiced sounds is spectrally shaped by using a linear predictive coding envelope from the long-term prediction error