Encoding device, decoding device, and method thereof

1. An encoding apparatus comprising:

a processor, the processor comprising:

a first encoder that encodes a portion in a low band of an input speech/audio signal to generate first encoded data, the low band being a band lower than a predetermined frequency;

a first decoder that decodes the first encoded data to generate a first decoded signal;

a second encoder that encodes a predetermined band portion of a residual signal calculated from the input speech/audio signal and the first decoded signal, to generate second encoded data; and

a filter that filters a portion in the low band of the first decoded signal or of a calculated signal calculated using the first decoded signal, to obtain a band enhancement parameter for obtaining a portion in a high band of the input speech/audio signal, the high band being a band higher than the predetermined frequency.

2. The encoding apparatus according to claim 1 , further comprising:

a second decoder that decodes the second encoded data to generate a second decoded signal; and

an adder that adds together the first decoded signal and the second decoded signal to generate an addition signal,

wherein the filter uses the addition signal as the calculated signal, filters a portion in the low band of the addition signal, to obtain the band enhancement parameter for obtaining the portion of the input speech/audio signal in the high band.

3. The encoding apparatus according to claim 1 , further comprising a gain information generator that calculates gain information that adjusts per-subband energy after the filtering.

4. The encoding apparatus according to claim 1 , wherein the band enhancement parameter includes at least one of a pitch coefficient and a filter coefficient.

5. The encoding apparatus according to claim 2 , further comprising a gain information generator that calculates gain information that adjusts per-subband energy after the filtering.

6. The encoding apparatus according to claim 2 , wherein the band enhancement parameter includes at least one of a pitch coefficient and a filter coefficient.

7. The encoding apparatus according to claim 3 , wherein the band enhancement parameter includes at least one of a pitch coefficient and a filter coefficient.

8. A decoding apparatus that uses a scalable codec with an r-layer configuration (where r is an integer of 2 or more), the decoding apparatus comprising:

a processor, the processor comprising:

a receiver that receives a band enhancement parameter calculated using an m'th-layer decoded speech/audio signal (where m is an integer less than or equal to r) in an encoding apparatus; and

a decoder that generates a high-band component using the band enhancement parameter and a low-band component of an n'th-layer decoded speech/audio signal (where n is an integer less than or equal to r),

wherein the decoder generates a high-band component of a decoded signal of an n'th layer different from an m'th layer (where m≠n) using the band enhancement parameter.

9. The decoding apparatus according to claim 8 , wherein:

the receiver further receives gain information transmitted from the encoding apparatus; and

the decoder generates the high-band component of the n'th-layer decoded speech/audio signal using the gain information instead of the band enhancement parameter, or using the band enhancement parameter and the gain information.

10. The decoding apparatus according to claim 8 , wherein the band enhancement parameter includes at least one of a pitch coefficient and a filter coefficient.

11. A decoding apparatus comprising:

a processor, the processor comprising:

a receiver that receives, transmitted from an encoding apparatus, first encoded data in which a portion in a low band of an input speech/audio signal to the encoding apparatus is encoded, the low band being a band lower than a predetermined frequency; second encoded data in which a predetermined band portion of a residue of a first decoded spectrum is encoded, the residue being obtained by decoding the first encoded data and a spectrum of the input speech/audio signal; and a band enhancement parameter for obtaining a portion in a high band of the input speech/audio signal, which is a band higher than the predetermined frequency, the band enhancement parameter being acquired by filtering a portion in the low band of the first decoded spectrum or of a first added spectrum resulting from adding together the first decoded spectrum and a second decoded spectrum obtained by decoding the second encoded data;

a first decoder that decodes the first encoded data to generate a third decoded spectrum in the low band;

a second decoder that decodes the second encoded data to generate a fourth decoded spectrum in the predetermined band portion; and

a third decoder that decodes a band portion not decoded by the first decoder or the second decoder by performing band enhancement of one of the third decoded spectrum, the fourth decoded spectrum, and a fifth decoded spectrum using the band enhancement parameter, the fifth decoded spectrum being generated using both of the third decoded spectrum and the fourth decoded spectrum.

12. The decoding apparatus according to claim 11 , wherein the receiver receives the first encoded data, the second encoded data, and the band enhancement parameter for obtaining the portion in the high band of the input speech/audio signal acquired by filtering the portion in the low band of the first added spectrum.

13. The decoding apparatus according to claim 11 , wherein the third decoder comprises:

an adder that adds together the third decoded spectrum and the fourth decoded spectrum to generate a second added spectrum; and

a filter that performs the band enhancement by filtering the third decoded spectrum, the fourth decoded spectrum, or the second added spectrum as the fifth decoded spectrum, using the band enhancement parameter.

14. The decoding apparatus according to claim 11 , wherein:

the receiver further receives gain information transmitted from the encoding apparatus; and

the third decoder decodes a band portion not decoded by the first decoder or the second decoder by performing band enhancement of one of the third decoded spectrum, the fourth decoded spectrum, and a fifth decoded spectrum using the gain information instead of the band enhancement parameter, or using the band enhancement parameter and the gain information, the fifth decoded spectrum being generated using both of the third decoded spectrum and the fourth decoded spectrum.

15. An encoding method comprising:

encoding, by a processor, a portion in a low band of an input speech/audio signal to generate first encoded data, the low band being a band lower than a predetermined frequency;

decoding, by a processor, the first encoded data to generate a first decoded signal;

encoding, by a processor, a predetermined band portion of a residual signal calculated from the input speech/audio signal and the first decoded signal, to generate second encoded data; and

filtering, by a processor, a portion in the low band of the first decoded signal or of a calculated signal calculated using the first decoded signal, to obtain a band enhancement parameter for obtaining a portion in a high band of the input speech/audio signal, the high band being a band higher than the predetermined frequency.

16. A decoding method that uses a scalable codec with an r-layer configuration (where r is an integer of 2 or more), the decoding method comprising:

receiving, by a processor, a band enhancement parameter calculated using an m'th-layer decoded speech/audio signal (where m is an integer less than or equal to r) in an encoding apparatus; and

generating, by a processor, a high-band component using the band enhancement parameter and a low-band component of an n'th-layer decoded speech/audio signal (where n is an integer less than or equal to r),

wherein generating the high-band component generates a high-band component of a decoded signal of an n'th layer different from an m'th layer (where m≠n) using the band enhancement parameter.

17. A decoding method comprising:

receiving, by a processor, transmitted from an encoding apparatus, first encoded data in which a portion in a low band of an input speech/audio signal to the encoding apparatus is encoded, the low band being a band lower than a predetermined frequency; second encoded data in which a predetermined band portion of a residue of a first decoded spectrum is encoded, the residue being obtained by decoding the first encoded data and a spectrum of the input speech/audio signal; and a band enhancement parameter for obtaining a portion in a high band of the input speech/audio signal, which is a band higher than the predetermined frequency, the band enhancement parameter being acquired by filtering a portion in the low band of the first decoded spectrum or of a first added spectrum resulting from adding together the first decoded spectrum and a second decoded spectrum obtained by decoding the second encoded data;

decoding, by a processor, the first encoded data to generate a third decoded spectrum in the low band;

decoding, by a processor, the second encoded data to generate a fourth decoded spectrum in the predetermined band portion; and

decoding, by a processor, a band portion not decoded by the decoding of the first encoded data or the decoding of the second encoded data, by performing band enhancement of one of the third decoded spectrum, the fourth decoded spectrum, and a fifth decoded spectrum using the band enhancement parameter, the fifth decoded spectrum being generated using both of the third decoded spectrum and the fourth decoded spectrum.