Patent ID: 7054809

Claim:
A method of selecting a coding rate for coding a plurality of frames of a speech signal at an average bit rate, said method comprising: obtaining a mode indicative of said average bit rate, wherein said mode is one of a premium mode, a standard mode and an economy mode; classifying a frame of said plurality of frames as being in a class from a plurality of classes, wherein said plurality of classes include a first class indicative of background noise or silence, a second class indicative of noise-like unvoiced speech, a third class indicative of pulse-like unvoiced speech, a fourth class indicative of transition into voiced speech, a fifth class indicative of unstable voiced speech, and a sixth class indicative of stable voiced speech; selecting from one of a premium algorithm, a standard algorithm and an economy algorithm corresponding to said mode, wherein each of said premium algorithm, said standard algorithm and said economy algorithm is different but each uses said class, a noise-to-signal ratio (NSR), a pitch correlation of a first half of said frame (Rp1), a pitch correlation of a second half of said frame (Rp2) and a sharpness of said frame (Shp) to determine said coding rate; and setting said coding rate for said frame at one of a plurality of rates according to said selected algorithm.