FREQUENCY BAND EXTENSION APPARATUS AND METHOD, ENCODING APPARATUS AND METHOD, DECODING APPARATUS AND METHOD, AND PROGRAM Russian patent published in 2012 - IPC G10L21/04 

FIELD: information technology.

SUBSTANCE: band-pass filters 13 obtain a plurality of subband signals from an input signal. A frequency envelope extracting circuit 14 extracts a frequency envelope from the plurality of subband signals. A highband signal generating circuit 15 generates highband signal components on the basis of the frequency envelope obtained by the frequency envelope extracting circuit 14, and the plurality of subband signals obtained by the band-pass filters 13. A frequency band extension apparatus 10 extends the frequency band of the input signal on the basis of the highband signal components generated by the highband signal generating circuit 15. The highband signal generating circuit includes a gain calculating circuit that finds a gain for each subband from the frequency envelope and applies the gain to the plurality of subband signals. The gain is calculated by a mapping function obtained by performing learning in advance with a wide-band signal as teacher data.

EFFECT: higher sound quality of reproducing a music signal owing to frequency band extension.

26 cl, 17 dwg