Encoding Device, Decoding Device, and Method Thereof

• US 20080027733A1
• Filed: 05/13/2005
• Published: 01/31/2008
• Est. Priority Date: 05/14/2004
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ehara, Hiroyuki, Oshikiri, Masahiro
• Granted Patent: US 8,417,515 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

There is disclosed an encoding device capable of appropriately adjusting the dynamic range of spectrum inserted according to the technique for replacing a spectrum of a certain band with a spectrum of another band. The device includes a spectrum modification unit (112) which modifies a first spectrum S1(k) of the band 0≦k<FL in various ways to change the dynamic range so that a way of modification for obtaining an appropriate dynamic range is checked. The information concerning the modification is encoded and given to a multiplexing unit (115). By using a second spectrum S2(k) having a valid signal band 0≦k.

Claims

1. A coding apparatus comprising:

a coding section that codes a high frequency band spectrum of an input signal; and

a limiting section that acquires a first low frequency band spectrum in which a coded signal of a low frequency band spectrum of the input signal is decoded, and generates a second low frequency band spectrum in which amplitude of the first low frequency band spectrum is uniformly limited,

wherein the coding section codes the high frequency band spectrum based on the second low frequency band spectrum.

2. The coding apparatus according to claim 1 further comprises a transmission section that transmits information about a way of limiting used at the limiting section together with coded information obtained by the coding section.

3. The coding apparatus according to claim 1, wherein the limiting section limits amplitude of the first low frequency band spectrum so that average deviation of the second low frequency band spectrum amplitude is equivalent to average deviation of amplitude of the high frequency band spectrum.

4. The coding apparatus according to claim 1, wherein the limiting section generates the second low frequency band spectrum by uniformly raising the amplitude of the first low frequency band spectrum to the power of a predetermined value within a range from 0 to 1.

5. The coding apparatus according to claim 1, wherein the coding section comprises:

a pitch filter that has the second low frequency band spectrum as an internal state; and

an estimating section that estimates the high frequency band spectrum using the pitch filter,

wherein characteristics of the pitch filter are coded so as to correspond to an estimation result of the estimating section.

6. The coding apparatus according to claim 5, wherein the pitch filter characteristics are indicated by the following transfer function.

7. The coding apparatus according to claim 1, wherein the limiting section estimates information about the way of limiting based on the first low frequency band spectrum and generates the second low frequency band spectrum using the estimated information.

8. The coding apparatus according to claim 1, wherein the limiting section comprises:

a dynamic range calculating section that calculates dynamic range information using the first low frequency band spectrum;

a modification information estimating section that estimates modification information for uniformly limiting amplitude of the first low frequency band spectrum using the dynamic range information; and

a modification section that uniformly limits amplitude of the first low frequency band spectrum using the estimated modification information.

9. The coding apparatus according to claim 7, wherein the limiting section comprises:

a modification information estimating section that estimates modification information for uniformly limiting amplitude of the first low frequency band spectrum using pitch information indicating periodicity of the input signal; and

a modification section that uniformly limits amplitude of the first low frequency band spectrum using the estimated modification information.

10. The coding apparatus according to claim 9, wherein the pitch information is configured using at least one of pitch gain and pitch period.

11. The coding apparatus according to claim 7, wherein the limiting section comprises:

a modification information estimating section that estimates modification information for uniformly limiting amplitude of the first low frequency band spectrum using spectrum outline information of the input signal; and

a modification section that uniformly limits amplitude of the first low frequency band spectrum using the estimated modification information.

12. The coding apparatus according to claim 11, wherein the modification information estimating section comprises:

a spectrum outline information storage section that stores a plurality of candidates for spectrum outline information; and

a dynamic range information storage section that stores a plurality of candidates for dynamic range information, wherein;

a candidate for spectrum outline information corresponding to spectrum outline information of the input signal is selected from the spectrum outline information storage section; and

the modification information is estimated by selecting a candidate for dynamic range information corresponding to the selected candidate for spectrum outline information from the dynamic range information storage section.

13. The coding apparatus according to claim 1, further comprising:

a first classifying section that classifies the first low frequency band spectrum into a plurality of groups according to differences in amplitude;

a first typical value acquiring section that acquires a typical value for amplitude for each group of the first low frequency band spectrum;

a second classifying section that classifies the high frequency band spectrum into a plurality of groups according to differences in amplitude; and

a second typical value acquiring section that acquires a typical value for amplitude for each group of the high frequency band spectrum,

wherein the limiting section uniformly limits the amplitude of the first low frequency band spectrum based on the typical value for each group of the first low frequency band spectrum and the typical value for each group of the high frequency band spectrum.

14. The coding apparatus according to claim 13, wherein the limiting section obtains amplitude between the typical values by carrying out linear interpolation on the typical values.

15. The coding apparatus according to claim 13, wherein the limiting section uniformly limits the amplitude of the first low frequency band spectrum based on a ratio between the typical value for each group of the first low frequency band spectrum and the typical value for each group of the high frequency band spectrum.

16. The coding apparatus according to claim 13, wherein the first and second typical value acquiring sections acquire an average value or central value of the amplitude for each group.

19. A communication terminal apparatus comprising the coding apparatus according to claim 1.

20. A base station apparatus comprising the coding apparatus according to claim 1.

17. A decoding apparatus comprising:

a converting section that generates a first low frequency band spectrum in which a decoded signal of code of a low frequency band spectrum included in code generated in a coding apparatus is converted to a frequency domain signal;

a decoding section that decodes code of a high frequency band spectrum included in the code generated in the coding apparatus; and

a limiting section that generates a second low frequency band spectrum in which amplitude of the first low frequency band spectrum is uniformly limited according to spectrum modification information included in the code generated in the coding apparatus,

wherein the decoding section decodes the code of the high frequency band spectrum based on the second low frequency band spectrum.

21. A communication terminal apparatus comprising the decoding apparatus according to claim 17.

22. A base station apparatus comprising the decoding apparatus according to claim 17.

18. A decoding apparatus comprising:

a converting section that generates a first low frequency band spectrum in which a decoded signal of code of a low frequency band spectrum included in code generated in a coding apparatus is converted to a frequency domain signal;

a decoding section that decodes code of a high frequency band spectrum included in the code generated in the coding apparatus; and

a limiting section that generates a second low frequency band spectrum in which amplitude of the first low frequency band spectrum is uniformly limited,

wherein the limiting section estimates information about a way of limiting based on the first low frequency band spectrum and generates the second low frequency band spectrum using the estimated information; and

the decoding section decodes the code of the high frequency band spectrum based on the second low frequency band spectrum.

23. A communication terminal apparatus comprising the decoding apparatus according to claim 18.

24. A base station apparatus comprising the decoding apparatus of claim 18.

25. A coding method comprising:

a coding step of coding a high frequency band spectrum of an input signal;

an acquiring step of acquiring a first low frequency band spectrum in which a coded signal of the low frequency band spectrum of the input signal is decoded; and

a limiting step of generating a second low frequency band spectrum in which amplitude of the first low frequency band spectrum is uniformly limited,

wherein the coding step codes the high frequency band spectrum based on the second low frequency band spectrum.

26. A decoding method comprising:

a conversion step of generating a first low frequency band spectrum in which a decoded signal of code of a low frequency band spectrum included in code generated in a coding apparatus is converted to a frequency domain signal;

a decoding step of decoding code of a high frequency band spectrum included in the code generated in the coding apparatus;

an acquisition step of acquiring spectrum modification information included in the code generated in the coding apparatus; and

a limiting step of generating a second low frequency band spectrum in which amplitude of the first low frequency band spectrum is uniformly limited according to the spectrum modification information,

wherein the decoding step decodes the high frequency band spectrum based on the second low frequency band spectrum.

27. A decoding method comprising:

a conversion step of generating a first low frequency band spectrum in which a decoded signal of code of a low frequency band spectrum included in code generated in a coding apparatus is converted to a frequency domain signal;

a decoding step of decoding code of a high frequency band spectrum included in the code generated in the coding apparatus; and

a limiting step of generating a second low frequency band spectrum in which amplitude of the first low frequency band spectrum is uniformly limited, wherein;

the limiting step estimates information about a way of limiting based on the first low frequency band spectrum and generates the second low frequency band spectrum using the estimated information; and

the decoding step decodes the code of the high frequency band spectrum based on the second low frequency band spectrum.