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 first coding section that encodes a low band part of an input signal including at least one of a speech signal and a music signal to generate first encoded data, the low band part being equal to or lower than a predetermined frequency; a normalization section that normalizes a first spectrum to generate a normalized spectrum, the first spectrum being obtained by decoding the first encoded data; a band searching section that makes a search to find a particular band having a largest correlation value between the normalized spectrum and a second spectrum that is a spectrum in a high band part of the input signal, the high band part being higher than the predetermined frequency; a gain calculating section that calculates a gain between the second spectrum and a third spectrum that is a spectrum obtained by copying the normalized spectrum in the particular band to the high band part; and a second coding section that encodes information including the particular band and the gain to generate second encoded data, wherein, the normalization section includes:
a largest value searching section that makes a search to find a largest value in amplitude of the first spectrum in each of a plurality of sub-bands resulting from division of the low band part; andan amplitude normalization section that normalizes the first spectrum included in each of the sub-bands using the largest value in the amplitude of the sub-band to obtain the normalized spectrum.