Encoding method and apparatus, and decoding method and apparatus

摘要

An encoding method of an encoder is provided. The encoder generates first MDCT coefficients by transforming an input signal, and generates MDCT indices by quantizing the first MDCT coefficients. The encoder generates second MDCT coefficients by dequantizing the MDCT indices, and calculates MDCT residual coefficients using differences between the first MDCT coefficients and the second MDCT coefficients. The encoder generates a residual index by encoding the MDCT residual coefficients, and generates gain indices corresponding to gains from the first MDCT coefficients and the second MDCT coefficients.

主权项

1. An encoding method of an encoder, the method comprising:
transforming an input signal to generate first modified discrete cosine transform (MDCT) coefficients; quantizing the first MDCT coefficients to generate MDCT indices; dequantizing the MDCT indices to generate second MDCT coefficients; computing MDCT residual coefficients using differences between the first MDCT coefficients and the second MDCT coefficients; encoding the MDCT residual coefficients to generate a residual index; generating gain indices corresponding to gains from the first MDCT coefficients and the second MDCT coefficients; and multiplexing the MDCT indices, the residual index, and the gain indices by a multiplexer to generate a bit stream, wherein generating the residual index comprises selecting an index of a sub-band with a largest energy of MDCT residual coefficients among a plurality of sub-bands, and wherein encoding the MDCT residual coefficients comprises selecting a pulse at a position corresponding to a predetermined number of MDCT residual coefficients, and generating the gain indices comprises computing exponents that are logarithms of magnitudes of the second MDCT coefficients at positions excluding the position of the pulse.