Patent ID: 6915256

Claim:
A method on an information processing system for quantizing pitch information of audio, comprising: capturing audio representing a numbered frame of a plurality of numbered frames; calculating a class of the frame, wherein a class is any one of a voiced class and an unvoiced class; if the frame is a voiced class, calculating a pitch for the frame; if the frame is an even numbered frame and a voiced class, calculating a codeword of a first length by quantizing the pitch of the frame absolutely; if the frame is an even numbered frame and an unvoiced class, calculating a codeword of the first length indicating a frame of unvoiced class; if the frame is an odd numbered frame and a voiced class and at least one of the three frames immediately preceding the frame is reliable, calculating a codeword of a second length by quantizing the pitch of the frame differentially referencing a quantized pitch of the nearest preceding reliable frame, wherein the first length is greater than the second length; if the frame is an odd numbered frame and a voiced class and each of the three frames immediately preceding the frame is not reliable, calculating a codeword of the second length by quantizing the pitch of the frame absolutely; and if the frame is an odd numbered frame and an unvoiced class, calculating a codeword of the second length indicating a frame of unvoiced class.