Frequency band extension apparatus, frequency band extension method, and program

A frequency band extension method comprising:

• dividing an input signal, having a predetermined bandwidth, into a plurality of sub-band signals of a plurality of sub-bands within the predetermined bandwidth;
• calculating, for each of the plurality of sub-bands, a low frequency sub-band power of the input signal as a feature value;
• estimating, for each high frequency sub-band of the plurality of sub-bands, a power of a high frequency sub-band of the input signal based on the feature values to obtain high frequency sub-band power estimation values;
• comparing, for each of the high frequency sub-bands, a respective high frequency sub-band power and a respective high-frequency sub-band power estimation value associated with a respective high frequency sub-band;
• and
• generating a high-frequency signal of the input signal, for each of the high frequency sub-bands, using the respective high frequency sub-band power when a result of the comparison indicates that the respective high frequency sub-band power is larger than the respective high-frequency sub-band power estimation value or using the respective high-frequency sub-band power estimation value when the result of the comparison indicates that the respective high-frequency sub-band power estimation value is larger than the respective high frequency sub-band power.

A non-transitory computer-readable medium having embodied thereon a program, which when executed by a computer causes the computer to execute a method, the method comprising:

• dividing an input signal, having a predetermined bandwidth, into a plurality of sub-band signals of a plurality of sub-bands within the predetermined bandwidth;
• calculating, for each of the plurality of sub-bands, a low frequency sub-band power of the input signal as a feature value;
• estimating, for each high frequency sub-band of the plurality of sub-bands, a power of a high frequency sub-band of the input signal based on the feature values to obtain high frequency sub-band power estimation values;
• comparing, for each of the high frequency sub-bands, a respective high frequency sub-band power and a respective high-frequency sub-band power estimation value associated with a respective high frequency sub-band;
• and
• generating a high-frequency signal of the input signal, for each of the high frequency sub-bands, using the respective high frequency sub-band power when a result of the comparison indicates that the respective high frequency sub-band power is larger than the respective high-frequency sub-band power estimation value or using the respective high-frequency sub-band power estimation value when the result of the comparison indicates that the respective high-frequency sub-band power estimation value is larger than the respective high frequency sub-band power.