| 摘要 |
PROBLEM TO BE SOLVED: To perform a plurality of decoding operations differed in bit rate, enhance the coding efficiency, and minimize the deterioration of a regenerated sound even at a low bit rate. SOLUTION: From the input signal from a terminal 101, a low-pass side signal is taken out by a LPF(low pass filter) 102, LPC-analyzed by a LPC analyzing and quantizing part 130, a LPC residual which is a short-range predictive residual is determined by a LPC reverse filter 111, a pitch is then determined by a pitch analyzing circuit 115, and a long-range prediction is performed by a pitch reverse filter 112 to determine a pitch residual. This pitch residual is MDCT-processed by a MDCT(modified discrete cosine transformation) circuit 113, and vector-quantized by a VQ(vector quantizing) circuit 114, and the quantized index is transmitted together with pitch lag and pitch gain. As the parameter for expressing LPC coefficient, a SLP (line spectrum pair) is transmitted. |
