Frequency band extending device and method, encoding device and method, decoding device and method, and program

• US 9,208,795 B2
• Filed: 09/29/2010
• Issued: 12/08/2015
• Est. Priority Date: 10/07/2009
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamamoto, Yuki, Chinen, Toru, Honma, Hiroyuki, Mitsufuji, Yuhki
• Primary Examiner(s): NGUYEN, MINH TRANG T
• Application Number:
  US13/499,559
• Publication Number:
  US 20120243526A1
• Time in Patent Office: 1,896 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G10L 19/0208 Subband vocoders
• CPC Class Codes: G10L 21/038 using band spreading techniques
• CPC Class Codes: G10L 21/0388 Details of processing therefor

Abstract

The present invention relates to a frequency band extending device and method, an encoding device and method, a decoding device and method, and a program, whereby music signals can be played with higher sound quality due to the extension of frequency bands.

A bandpass filter 13 divides an input signal into multiple sub-band signals, a feature amount calculating circuit 14 calculates feature amount using at least one of the multiple divided sub-band signals and the input signal, a high frequency sub-band power estimating circuit 15 calculates an estimated value of a high frequency sub-band power based on the calculated feature amount, a high frequency signal generating circuit 16 generates a high frequency signal component based on the multiple sub-band signals divided by the bandpass filter 13, and the estimated value of the high frequency sub-band power calculated by the high frequency sub-band power estimating circuit 15. A frequency band extending device 10 extends the frequency band of the input signal using a high frequency signal component. The present invention may be applied to a frequency band extending device, for example.

Claims

1. A decoding device comprising:

demultiplexing means configured to demultiplex input encoded data into at least low frequency encoded data and an index;

low frequency decoding means configured to decode said low frequency encoded data to generate a low frequency signal;

sub-band dividing means configured to divide the band of said low frequency signal into a plurality of low frequency sub-bands to generate a low frequency sub-band signal for each of said low frequency sub-bands; and

generating means configured to generate a high frequency signal based on said index and said low frequency sub-band signal.

2. The decoding device according to claim 1, wherein said index is obtained, at a device which encodes an input signal and outputs said encoded data, based on said input signal before encoding, and said high frequency signal estimated from said input signal.

3. The decoding device according to claim 1, wherein said index has not been encoded.

4. The decoding device according to claim 1, wherein said index is information indicating an estimating coefficient used for generation of said high frequency signal.

5. The decoding device according to claim 4, wherein said generating means generate said high frequency signal based on, of a plurality of said estimating coefficients, said estimating coefficient indicated by said index.

6. The decoding device according to claim 4, said generating means comprising:

feature amount calculating means configured to calculate feature amount that expresses a feature of said encoded data using at least one of said low frequency sub-band signal and said low frequency signal;

high frequency sub-band power calculating means configured to calculate a high frequency sub-band power of a high frequency sub-band signal of said high frequency sub-band by calculation using said feature amount and said estimating coefficient regarding each of a plurality of high frequency sub-bands making up the band of said high frequency signal; and

high frequency signal generating means configured to generate said high frequency signal based on said high frequency sub-band power and said low frequency sub-band signal.

7. The decoding device according to claim 6, wherein said high frequency sub-band power calculating means calculate said high frequency sub-band power of said high frequency sub-band by linearly combining a plurality of said feature amount using said estimating coefficient prepared for each of said high frequency sub-bands.

8. The decoding device according to claim 7, wherein said feature amount calculating means calculate a low frequency sub-band power of said low frequency sub-band signal for each of said low frequency sub-bands as said feature amount.

9. The decoding device according to claim 6, wherein said index is information indicating said estimating coefficient whereby said high frequency sub-band power most approximate to said high frequency sub-band power obtained from said high frequency signal of said input signal before encoding is obtained as a result of comparison between said high frequency sub-band power obtained from said high frequency signal of said input signal before encoding and said high frequency sub-band power generated based on said estimating coefficient of a plurality of said estimating coefficients.

10. The decoding device according to claim 9, wherein said index is information indicating said estimating coefficient whereby the sum of squares of difference between said high frequency sub-band power obtained from said high frequency signal of said input signal before encoding, and said high frequency sub-band power generated based on said estimating coefficient obtained for each of said high frequency sub-bands, becomes the minimum.

11. The decoding device according to claim 9, wherein said encoded data further includes difference information indicating difference between said high frequency sub-band power obtained from said high frequency signal of said input signal before encoding, and said high frequency sub-band power generated based on said estimating coefficient.

12. The decoding device according to claim 11, wherein said difference information has been encoded.

13. The decoding device according to claim 11, wherein said high frequency sub-band power calculating means add said difference indicated with said difference information included in said encoded data to said high frequency sub-band power obtained by calculation using said feature amount and said estimating coefficient;

and wherein said high frequency signal generating means generate said high frequency signal based on said high frequency sub-band power to which said difference has been added, and said ow frequency sub-band signal.

14. The decoding device according to claim 6, wherein said estimating coefficient is obtained by regression analysis using the least square method with said feature amount as an explanatory variable and said high frequency sub-band power as an explained variable.

15. The decoding device according to claim 6, further comprising, with said index being information indicating a difference vector made up of said difference for each of said high frequency sub-bands wherein difference between said high frequency sub-band power obtained from said high frequency signal of said input signal before encoding, and said high frequency sub-band power generated based on said estimating coefficient as an element:

coefficient output means configured to obtain distance between a representative vector or representative value in feature space of said difference with said difference of said high frequency sub-bands as an element, obtained beforehand for each of said estimating coefficients, and said difference vector indicated by said index, and to supply said estimating coefficient of said representative vector or said representative value whereby said distance is the shortest, of a plurality of said estimating coefficients, to said high frequency sub-band power calculating means.

16. The decoding device according to claim 4, wherein said index is information indicating said estimating coefficient of a plurality of said estimating coefficients whereby as a result of comparison between said high frequency signal of said input signal before encoding, and said high frequency signal generated based on said estimating coefficient, said high frequency signal most approximate to said high frequency signal of said input signal before encoding is obtained.

17. The decoding device according to claim 4, wherein said estimating coefficient is obtained by regression analysis.

18. The decoding device according to claim 1, wherein said generating means generate said high frequency signal based on information obtained by decoding said encoded index.

19. The decoding device according to claim 18, wherein said index has been subjected to entropy encoding.

20. A decoding method comprising:

a demultiplexing step arranged to demultiplex input encoded data into at least low frequency encoded data and an index;

a low frequency decoding step arranged to decode said ow frequency encoded data to generate a low frequency signal;

a sub-band dividing step arranged to divide the band of said low frequency signal into a plurality of low frequency sub-bands to generate a low frequency sub-band signal for each of said low frequency sub-bands; and

a generating step arranged to generate a high frequency signal based on said index and said low frequency sub-band signal.

21. A non-transitory computer-readable medium causing a computer to execute processing comprising:

a demultiplexing step arranged to demultiplex input encoded data into at least low frequency encoded data and an index;

a low frequency decoding step arranged to decode said low frequency encoded data to generate a low frequency signal;

a sub-band dividing step arranged to divide the band of said low frequency signal into a plurality of low frequency sub-bands to generate a low frequency sub-band signal for each of said low frequency sub-bands; and

a generating step arranged to generate a high frequency signal based on said index and said low frequency sub-band signal.

22. A decoding device comprising:

demultiplexing means configured to demultiplex input encoded data into low frequency encoded data and an index for obtaining an estimating coefficient used for generation of a high frequency signal;

low frequency decoding means configured to decode said low frequency encoded data to generate a low frequency signal;

sub-band dividing means configured to divide the band of said low frequency signal into a plurality of low frequency sub-bands to generate a low frequency sub-band signal for each of said low frequency sub-bands;

feature amount calculating means configured to calculate feature amount that expresses a feature of said encoded data using at least one of said low frequency sub-band signal and said low frequency signal;

high frequency sub-band power calculating means configured to calculate a high frequency sub-band power of the high frequency sub-band signal of said high frequency sub-band by multiplexing said feature amount by said estimating coefficient determined by said index of a plurality of said estimating coefficients prepared beforehand regarding each of a plurality of high frequency sub-bands making up the band of said high frequency signal, and obtaining the sum of said feature amount by which said estimating coefficient has been multiplied; and

high frequency signal generating means configured to generate said high frequency signal using said high frequency sub-band power and said low frequency sub-band signal.

23. The decoding device according to claim 22, wherein said feature amount calculating means calculate a low frequency sub-band power of said low frequency sub-band signal for each of said low frequency sub-bands as said feature amount.

24. The decoding device according to claim 23, wherein said index is information for obtaining said estimating coefficient of said plurality of said estimating coefficients whereby the sum of squares of difference obtained for each of said high frequency sub-bands, which is difference between said high frequency sub-band power obtained from the true value of said high frequency signal, and said high frequency sub-band power generated with said estimating coefficient, becomes the minimum.

25. The decoding device according to claim 24, wherein said index further include difference information indicating difference between said high frequency sub-band power obtained from said true value, and said high frequency sub-band power generated with said estimating coefficient;

and wherein said high frequency sub-band power calculating means further add said difference indicated by said difference information included in said index to said high frequency sub-band power obtained by obtaining the sum of said feature amount by which said estimating coefficient has been multiplied;

and wherein said high frequency signal generating means generate said high frequency signal using said high frequency sub-band power to which said difference has been added by said high frequency sub-band power calculating means, and said low frequency sub-band signal.

26. The decoding device according to claim 22, wherein said index is information indicating said estimating coefficient.

27. The decoding device according to claim 22, wherein said index is information obtained by information indicating said estimating coefficient being subjected to entropy encoding;

and wherein said high frequency sub-band power calculating means calculate said high frequency sub-band power using said estimating coefficient indicated by information obtained by decoding said index.

28. The decoding device according to claim 22, wherein said plurality of said estimating coefficients are obtained beforehand by regression analysis using the least square method with said feature amount as an explanatory variable and said high frequency sub-band power as an explained variable.

29. The decoding device according to claim 22, further comprising, with said index being information indicating a difference vector made up of said difference for each of said high frequency sub-bands wherein difference between said high frequency sub-band power obtained from the true value of said high frequency signal, and said high frequency sub-band power generated with said estimating coefficient as an element:

coefficient output means configured to obtain distance between a representative vector or representative value in feature space of said difference with said difference of said high frequency sub-bands as an element, obtained beforehand for each of said estimating coefficients, and said difference vector indicated by said index, and to supply said estimating coefficient of said representative vector or said representative value whereby said distance is the shortest, of a plurality of said estimating coefficients, to said high frequency sub-band power calculating means.

30. A decoding method comprising:

a demultiplexing step arranged to demultiplex input encoded data into low frequency encoded data and an index for obtaining an estimating coefficient used for generation of a high frequency signal;

a low frequency decoding step arranged to decode said low frequency encoded data to generate a low frequency signal;

a sub-band dividing step arranged to divide the band of said low frequency signal into a plurality of low frequency sub-bands to generate a low frequency sub-band signal for each of said low frequency sub-bands;

a feature amount calculating step arranged to calculate feature amount that expresses a feature of said encoded data using at least one of said low frequency sub-band signal and said low frequency signal;

a high frequency sub-band power calculating step arranged to calculate a high frequency sub-band power of the high frequency sub-band signal of said high frequency sub-band by multiplexing said feature amount by said estimating coefficient determined by said index of a plurality of said estimating coefficients prepared beforehand regarding each of a plurality of high frequency sub-bands making up the band of said high frequency signal, and obtaining the sum of said feature amount by which said estimating coefficient has been multiplied; and

a high frequency signal generating step arranged to generate said high frequency signal using said high frequency sub-band power and said low frequency sub-band signal.

31. A non-transitory computer-readable medium causing a computer to execute processing comprising:

a demultiplexing step arranged to demultiplex input encoded data into low frequency encoded data and an index for obtaining an estimating coefficient used for generation of a high frequency signal;

a low frequency decoding step arranged to decode said low frequency encoded data to generate a low frequency signal;

a sub-band dividing step arranged to divide the band of said low frequency signal into a plurality of low frequency sub-bands to generate a low frequency sub-band signal for each of said low frequency sub-bands;

a feature amount calculating step arranged to calculate feature amount that expresses a feature of said encoded data using at least one of said low frequency sub-band signal and said low frequency signal;

a high frequency sub-band power calculating step arranged to calculate a high frequency sub-band power of the high frequency sub-band signal of said high frequency sub-band by multiplexing said feature amount by said estimating coefficient determined by said index of a plurality of said estimating coefficients prepared beforehand regarding each of a plurality of high frequency sub-bands making up the band of said high frequency signal, and obtaining the sum of said feature amount by which said estimating coefficient has been multiplied; and

a high frequency signal generating step arranged to generate said high frequency signal using said high frequency sub-band power and said low frequency sub-band signal.