Patent ID: 8019600

Claim:
A speech signal compression apparatus, including at least one processing device comprising: a transform unit, using the at least one processing device, to transform a speech signal including a plurality of subframes into a frequency domain and obtain frequency coefficients; a magnitude quantization unit to transform magnitudes of the frequency coefficients for each of the subframes of the speech signal, quantize the transformed magnitudes and obtain magnitude quantization indices; a sign quantization unit to quantize each sign of each of the frequency coefficients and obtain sign quantization indices; and a packetizing unit to generate the magnitude quantization indices and the sign quantization indices as a speech packet, wherein the frequency coefficients for each of the subframes are combined into a plurality of groups according to a time-varying property in energy of the speech signal and a two-dimensional transform is performed on each group according to the time-varying property of the speech signal, the frequency coefficients being combined into groups based on a uniformity of the subframes in relation to neighboring subframes.