Subband vector excitation coding with adaptive bit-allocation

A study of the combination of VSC (vector excitation coding) with subband coding is reported. In subband VXC (SBVXC), the burden of redundancy removal is split between the frequency domain and time domain to take advantage of both predictive coding and subband coding techniques. The conventional adaptive bit-allocation method used in subband coding has been generalized for use in SBVXC. Simulated comparisons of several coding schemes, including one comparing SBVXC with the full-band VXC, are presented. Results show that a two-band version of SBVXC can produce fairly clear, intelligible, and natural-sounding synthetic speech at 4.8 kb/s and very high quality speech at 8 kb/s with a reasonable complexity.<>