Patent ID: 6820052
Filing Date: 2004-11-16
Classification: G10L

Abstract:
A method for low bit rate speech coding of unvoiced speech, comprising;identifying an incoming speech frame as an unvoiced speech frame; performing linear predictive analysis on the unvoiced speech frame to create an unvoiced liner predictive residue; extracting high-time-resolution energy parameters from the unvoiced linear predictive residue, wherein extracting high-time-resolution energy parameters comprises extracting a number (M) of local energy parameters Ei, where i=1,2, . . . , M, is extracted from an unvoiced residue R[n] by performing the following steps; dividing N-sample residue R[n] into (Mâˆ’2) sub-blocks Xi, where i=2,3, . . . , Mâˆ’1, with each block Xi having a length of L=N/(Mâˆ’2); obtaining an L-sample past residue block X1 from a past quantized residue of a previous frame; obtaining an L-sample future residue block XM from the linear predictive residue of a following frame; and creating a number M of local energy parameters where Ei, where i=1,2, . . . , M, from each of the M blocks Xi, where i=1,2, . . . , M, in accordance with the following equation; Ei=1L*&Sum;m=1L&it;Xi&af;[m]*Xi&af;[m];encoding the high-time-resolution energy parameters; quantizing the high-time-resolution energy parameters to form quantized energy vectors; forming a high-time-resolution energy envelope; generating a quantized unvoiced residue by coloring random noise with the high-time-resolution energy envelope; and generating a quantized unvoiced speech frame.