Device and method for bandwidth extension for audio signals

1. An audio signal decoding apparatus, comprising:

a receiver that receives an encoded information;

a memory; and

a processor that

demultiplexes the encoded information, the encoded information including encoding parameters that are used for decoding a low frequency spectrum and index information that identify a most correlated portion from a low frequency spectrum for one or more high frequency subbands;

replicates a high frequency subband spectrum based on the index information using a synthesized low frequency spectrum, the synthesized low frequency spectrum being obtained by decoding the encoding parameters;

estimates a frequency of a harmonic component in the synthesized low frequency spectrum;

adjusts a frequency of a harmonic component in the high frequency subband spectrum using the estimated harmonic frequency; and

generates an output signal using the synthesized low frequency spectrum and the high frequency subband spectrum;

wherein, within the harmonic frequency estimation, the processor

splits a preselected portion of the synthesized low frequency spectrum into plural blocks;

identifies a frequency of a spectral peak having a maximum amplitude in each of the plural blocks;

calculates a spacing between each of the identified spectral peak frequencies; and

calculates the harmonic frequency using the spacing between the identified spectral peak frequencies.

2. The audio signal decoding apparatus according to claim 1 ,

wherein the processor calculates the harmonic frequency using an average value of the spacing between the identified spectral peak frequencies.

3. An audio signal decoding apparatus, comprising:

a receiver that receives an encoded information;

a memory; and

a processor that

demultiplexes the encoded information, the encoded information including encoding parameters that are used for decoding a low frequency spectrum and index information that identify a most correlated portion from a low frequency spectrum for one or more high frequency subbands;

replicates a high frequency subband spectrum based on the index information using a synthesized low frequency spectrum, the synthesized low frequency spectrum being obtained by decoding the encoding parameters;

estimates a frequency of a harmonic component in the synthesized low frequency spectrum;

adjusts a frequency of a harmonic component in the high frequency subband spectrum using the estimated harmonic frequency; and

generates an output signal using the synthesized low frequency spectrum and the high frequency subband spectrum;

wherein, within the harmonic frequency adjustment, the processor further

adjusts a plurality of spectral peak frequencies so that a spacing between the spectral peak frequencies after the adjustment is equal to the estimated harmonic frequency, using, as a reference, a highest frequency of spectral peaks in the synthesized low frequency spectrum.

4. An audio signal decoding method, comprising:

receiving encoded information;

demultiplexing the encoded information, the encoded information including encoding parameters that are used for decoding a low frequency spectrum and index information that identify a most correlated portion from a low frequency spectrum for one or more high frequency subbands;

replicating a high frequency subband spectrum based on the index information using a synthesized low frequency spectrum, the synthesized low frequency spectrum being obtained by decoding the encoding parameters;

estimating a frequency of a harmonic component in the synthesized low frequency spectrum;

adjusting a frequency of a harmonic component in the high frequency subband spectrum using the estimated harmonic frequency; and

generating an output signal using the synthesized low frequency spectrum and the high frequency subband spectrum;

wherein, within an harmonic frequency estimation,

splitting a preselected portion of the synthesized low frequency spectrum into plural blocks;

identifying a frequency of a spectral peak having a maximum amplitude in each of the plural blocks;

calculating a spacing between each of the identified spectral peak frequencies; and

calculating the harmonic frequency using the spacing between the identified spectral peak frequencies.

5. The audio signal decoding method according to claim 4 ,

wherein calculating the harmonic frequency uses an average value of the spacing between the identified spectral peak frequencies.

6. An audio signal decoding method, comprising:

receiving an encoded information;

demultiplexing the encoded information, the encoded information including encoding parameters that are used for decoding a low frequency spectrum and index information that identify a most correlated portion from a low frequency spectrum for one or more high frequency subbands;

replicating a high frequency subband spectrum based on the index information using a synthesized low frequency spectrum, the synthesized low frequency spectrum being obtained by decoding the encoding parameters;

estimating a frequency of a harmonic component in the synthesized low frequency spectrum;

adjusting a frequency of a harmonic component in the high frequency subband spectrum using the estimated harmonic; and

generating an output signal using the synthesized low frequency spectrum and the high frequency subband spectrum;

wherein, within the harmonic frequency adjustment, adjusting a plurality of spectral peak frequencies so that a spacing between the spectral peak frequencies after the adjustment is equal to the estimated harmonic frequency, using, as a reference, a highest frequency of spectral peaks in the synthesized low frequency spectrum.