Patent ID: 8653991
Filing Date: 2014-02-18
Classification: G10L

Abstract:
1. A coding method that codes a number sequence based on the μ-law or the A-law according to the ITU-T G.711, referred to as a second signal sequence hereinafter, comprising: letting a quantized value, a magnitude of which is 0 based on the μ-law according to the ITU-T G.711 or a magnitude of which is 1 based on to the A-law according to the ITU-T G.711, as a minimum quantized value, a signal sequence transformation step of in a case where a number corresponding to a positive minimum magnitude of quantized value and a number corresponding to a negative minimum magnitude of quantized value occur in said second signal sequence, replacing the numbers in said second signal sequence with newly assigned numbers and outputting a number sequence formed thereby, referred to as a transformed second signal sequence hereinafter, the newly assigned numbers corresponding to quantized values so that a positive maximum magnitude of quantized value corresponds to +127, a negative maximum magnitude of quantized value corresponds to −128 and relation in magnitude of the quantized values is maintained in the newly assigned numbers, in a case where a number corresponding to a positive minimum magnitude of quantized value and a number corresponding to a negative minimum magnitude of quantized value do not occur in said second signal sequence, replacing the numbers in said second signal sequence with newly assigned numbers and outputting a number sequence formed thereby, referred to as a transformed second signal sequence hereinafter, the newly assigned numbers corresponding to quantized values excluding the positive minimum magnitude of quantized value and the negative minimum magnitude of quantized value so that a positive maximum magnitude of quantized value corresponds to +126, a negative maximum magnitude of quantized value corresponds to −127 and relation in magnitude of the quantized values is maintained in the newly assigned numbers, in a case where one of a number corresponding to a positive minimum magnitude of quantized value and a number corresponding to a negative minimum magnitude of quantized value does not occur in said second signal sequence, replacing the numbers in said second signal sequence with newly assigned numbers and outputting a number sequence formed thereby, referred to as a transformed second signal sequence hereinafter, the newly assigned numbers corresponding to quantized values excluding the minimum magnitude of quantized value corresponding to said one number so that a positive maximum magnitude of quantized value corresponds to +127, a negative maximum magnitude of quantized value corresponds to −127 and relation in magnitude of the quantized values is maintained in the newly assigned numbers; a prediction analysis step of performing a prediction analysis of said transformed second signal sequence to determine prediction coefficients; a quantization step of quantizing said prediction coefficients to determine quantized prediction coefficients; a predicted value calculation step of determining a transformed second predicted value sequence, which is a result of prediction of the transformed second signal sequence, using a previous transformed second signal sequence and said quantized prediction coefficients; a subtraction step of determining a prediction residual sequence between said transformed second predicted value sequence and said transformed second signal sequence; a coefficients coding step of coding said quantized prediction coefficients; and a residual coding step of coding said prediction residual sequence.