Encoding device, decoding device, encoding method and decoding method

摘要

By copying to a high-frequency band portion (extension band) a low-frequency band portion in which peaking has been set to a sufficiently low state, this encoding device is capable of preventing generation of a spectrum with overly high peaking in the high-frequency band portion, and of generating a high-quality extension band spectrum. This device comprises: a maximum value search unit which searches, in each of multiple sub-bands obtained by dividing the low-frequency band portion of an audio signal and/or music signal below a prescribed frequency, for the maximum value of the amplitude of a first spectrum obtained by decoding first encoded data, which is encoded data in the low-frequency band portion; and an amplitude normalization unit which obtains a normalized spectrum by normalizing, at the maximum values of the amplitude of each sub-band, the first spectrum contained in each sub-band.

主权项

1. A coding apparatus, comprising:
a memory that stores instructions; a processor that executes the instructions; a first coder that encodes a low band part of an input audio signal to generate first encoded data which is transmitted to a decoder side, the low band part being equal to or lower than a predetermined frequency; and a second coder; wherein, when executed by the processor, the instructions cause the coding apparatus to perform operations comprising: normalizing a first spectrum included in each of sub-bands obtained from dividing the low band part, using a largest amplitude value among the first spectrum included in each sub-band, and obtaining a first normalized low-frequency spectrum, the first spectrum being obtained by decoding the first encoded data; calculating energy of the first spectrum in each of a plurality of the sub-bands obtained from dividing the low band part, smoothing the energy of the first spectrum in the sub-bands to obtain smoothened sub-band energy, and normalizing the first spectrum using the smoothened sub-band energy to generate a second normalized low-frequency spectrum; selecting a first normalizer that obtains the first normalized low-frequency spectrum or a second normalizer that generates the second normalized low-frequency spectrum based on a feature value of the first spectrum obtained by decoding the first encoded data; searching for a particular band where a value of correlation between a second spectrum and the first normalized low-frequency spectrum is highest among a plurality of candidate bands, the second spectrum being a spectrum in a high band part of the input audio signal that is higher than the predetermined frequency; and wherein the second coder encodes the second spectrum, and encodes information including an identifier of the particular band for transmitting the information to the decoder side, when the first normalizer is selected.