On improving vector excitation coders through the use of spherical lattice codebooks (SLCs)

Two novel techniques for use in VXC (vector excitation coding) speech coders are presented. The first enables massive excitation codebooks (⩾20 b) to be used at realizable complexities by using a novel spherical lattice codebook for the excitation codebook. The second technique is a generalization of the gain-optimized error measure which allows any number of gains to be calculated for each excitation vector. This multiple-gain VXC can be thought of as a hybrid between multipulse and VXC