Audio Encoding Device, Audio Encoding Method, and Audio Encoding Program

• US 20080140425A1
• Filed: 01/06/2006
• Published: 06/12/2008
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Shimada, Osamu
• Granted Patent: US 8,082,156 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: G10L 19/0208 Subband vocoders
• CPC Class Codes: G10L 19/20 using sound class specific coding, hybrid encoders or object based coding
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

By using a high-range sub-band signal, a correction coefficient corresponding to importance of auditory sense is calculated to correct a noise level and generate additional signal information, thereby accurately reflecting the noise level of the sub-band important in the auditory sense. Thus, it is possible to calculate additional signal information reflecting the noise level of the sub-band important in the auditory sense according to importance with a small calculation amount. The calculation amount can further be reduced by using a correction coefficient based on the characteristic of an ordinary audio signal.

Claims

1-15. -15. (canceled)

16. An audio encoding device for dividing an input signal into a low-frequency-band signal having a low frequency band and a high-frequency-band signal having a high frequency band, mixing a signal obtained by converting said low-frequency-band signal and a noise signal, and encoding noise signal information that is used in expressing the high-frequency-band signal, comprising a means for obtaining said noise signal information by allowing importance of each frequency component to be reflected into it.

17. The audio encoding device according to claim 16, wherein in obtaining said noise signal information, calculating noise signal information by frequency bands into which importance of auditory sense of said high-frequency-band signal has been reflected, and calculating noise signal information that is used in common in a plurality of the frequency bands.

18. The audio encoding device according to claim 16, wherein in obtaining said noise signal information, employing said high-frequency-band signal to obtain a correction coefficient, and employing said correction coefficient to correct said noise signal information.

19. The audio encoding device according to claim 18, wherein in obtaining said correction coefficient, calculating a correction coefficient into which importance of auditory sense of each frequency component of said high-frequency-band signal has been reflected.

20. The audio encoding device according to claim 18, wherein in obtaining said correction coefficient, calculating energy by frequency bands of said high-frequency-band signal, and calculating a correction coefficient based upon said energy by frequency bands.

21. The audio encoding device according to one of claim 18 or claim 19, wherein in obtaining said correction coefficient, calculating a correction coefficient such that a value of the correction coefficient is small for a high frequency.

22. The audio encoding device accord to one of claim 16 or claim 17, wherein in obtaining said noise signal information, smoothing the noise signal information obtained by allowing importance of each frequency component of said high-frequency-band signal to be reflected at least in one of a time direction and a frequency direction.

23. The audio encoding device according to one of claim 18 to claim 20, wherein in obtaining said correction coefficient, smoothing the correction coefficient calculated responding to each frequency component of said high-frequency-band signal at least in one of a time direction and a frequency direction.

24. The audio encoding device according to one of claim 16 to claim 18, wherein said noise signal information is a noise level indicating a ratio of the noise signal over said high-frequency-band signal.

25. An audio encoding method for dividing an input signal into a low-frequency-band signal having a low frequency band and a high-frequency-band signal having a high frequency band, mixing a signal obtained by converting said low-frequency-band signal and a noise signal, and encoding noise signal information that is used in expressing the high-frequency-band signal, comprising a step of obtaining said noise signal information by allowing importance of each frequency component to be reflected into it.

26. The audio encoding method according to claim 25, wherein in obtaining said noise signal information, calculating noise signal information by frequency bands into which importance of auditory sense of said high-frequency-band signal has been reflected, and calculating noise signal information that is used in common in a plurality of the frequency bands.

27. The audio encoding method according to claim 25, wherein in obtaining said noise signal information, employing said high-frequency-band signal to obtain a correction coefficient, and employing said correction coefficient to correct said noise signal information.

28. The audio encoding method according to claim 27, wherein in obtaining said correction coefficient, calculating a correction coefficient into which importance of auditory sense of each frequency component of said high-frequency-band signal has been reflected.

29. The audio encoding method according to claim 27, wherein in obtaining said correction coefficient, calculating energy by frequency bands of said high-frequency-band signal, and calculating a correction coefficient based upon said energy by frequency bands.

30. The audio encoding method according to one of claim 27 or claim 28, wherein in obtaining said correction coefficient, calculating a correction coefficient such that a value of the correction coefficient is small for a high frequency.

31. The audio encoding method according to one of claim 25 or claim 26, wherein in obtaining said noise signal information, smoothing the noise signal information obtained by allowing importance of each frequency component of said high-frequency-band signal to be reflected at least in one of a time direction and a frequency direction.

32. The audio encoding method according to one of claim 27 to claim 29, wherein in obtaining said correction coefficient, smoothing the correction coefficient calculated responding to each frequency component of said high-frequency-band signal at least in one of a time direction and a frequency direction.

33. The audio encoding method according to one of claim 25 to claim 27, wherein said noise signal information is a noise level indicating a ratio of the noise signal over said high-frequency-band signal.

34. An audio encoding program for dividing an input signal into a low-frequency-band signal having a low frequency band and a high-frequency-band signal having a high frequency band, mixing a signal obtained by converting said low-frequency-band signal and a noise signal, and encoding noise signal information that is used in expressing the high-frequency-band signal, wherein causing an information processing unit to execute the process of obtaining said noise signal information by allowing importance of each frequency component to be reflected into it.