Device and method for bandwidth extension for audio signals

An audio signal decoding apparatus, comprising:

• a receiver that receives an encoded information;
• a memory;
• and
• a processor that
• demultiplexes the encoded information, including encoding parameters that are used for decoding a low frequency spectrum and index information that identifies 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 the plurality of spectral peak frequencies so that the spacing between the spectral peak frequencies after the adjustment is equal to the estimated harmonic frequency, using, as a reference, the highest frequency of the spectral peaks in the synthesized low frequency spectrum.

An audio signal decoding method, comprising:

• receiving encoded information;
• demultiplexing the encoded information, including encoding parameters that are used for decoding a low frequency spectrum and index information that identifies 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 spacing between each of the identified spectral peak frequencies;
• and
• calculating the harmonic frequency using the spacing between the identified spectral peak frequencies.

An audio signal decoding method, comprising:

• receiving an encoded information;
• demultiplexing the encoded information, including encoding parameters that are used for decoding a low frequency spectrum and index information that identifies 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 the plurality of spectral peak frequencies so that the spacing between the spectral peak frequencies after the adjustment is equal to the estimated harmonic frequency, using, as a reference, the highest frequency of the spectral peaks in the synthesized low frequency spectrum.