Encoding method and apparatus, decoding method and apparatus and recording medium

• US 6,169,973 B1
• Filed: 03/25/1998
• Issued: 01/02/2001
• Est. Priority Date: 03/31/1997
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Tsutsui, Kyoya, Shimoyoshi, Osamu
• Primary Examiner(s): Hudspeth, David R.
• Assistant Examiner(s): CHAWAN, VIJAY B
• Application Number:
  US09/048,150
• Time in Patent Office: 1,014 Days
• Field of Search: 704/229, 704/230, 704/222, 704/226, 704/201, 704/500-504, 704/233, 704/227, 369/124, 369/47
• US Class Current: 704/500
• CPC Class Codes: G11B 20/00007 Time or data compression or expansion audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: H04B 1/665 using psychoacoustic properties of the ear, e.g. masking effect
• CPC Class Codes: H04H 20/88 Stereophonic broadcast systems multiplex system in general H04J

Abstract

An encoding method and apparatus and a decodings method and apparatus in which the encoded information is decreased in volume and in which the encoding and decoding operations are performed with a smaller processing volume and a smaller buffer memory capacity. The apparatus includes a low range signal splitting circuit for separating low-range side signal components from L and R channel signals converted by a transform circuit into spectral signal components, and a channel synthesis circuit for synthesizing (L+R) channel signal components from the L and R channel spectral signal components. The apparatus also includes a high range signal separating circuit for separating the high range side signal components from the (L+R) channel signal components, a signal component encoding circuit for compression-encoding low-range side signal components and a signal component encoding circuit for compression-encoding the normalization coefficient information obtained on normalization of the (L+R) channel high-range signal components.

Claims

1. A method for encoding plural input audio signals, comprising the steps of:

generating plural lower frequency signals and higher frequency signals by splitting a signal derived from the plural input audio signals, wherein a number of the higher frequency signals is less than that of the plural input audio signals;

encoding each of said plural lower frequency signals;

encoding said higher frequency signals and generating encoding information obtained on said step of encoding said higher frequency signals; and

generating a codestring based on signals encoded by said step of encoding each of said lower frequency signals, the step of encoding said higher frequency signals and on said encoding information.

2. The encoding method as claimed in claim 1, wherein

said step of encoding higher frequency signals normalizes and encodes the higher frequency signals and also generates the encoding information, wherein the encoding information contains normalization coefficients based on said encoding of higher frequency signals.

3. The encoding method as claimed in claim 2, wherein

said step of splitting generates from a signal derived from the plural input audio signals common higher frequency signals for said plural input audio signals, wherein

said step of encoding higher frequency signals encodes the common higher frequency signals and generates the encoding information, wherein the encoding information contains normalization coefficient information based on said step of encoding higher frequency signals.

4. The encoding method as claimed in claim 1, wherein said step of splitting generates common higher frequency signals for said plural input audio signals from the signal derived from the plural input audio signals.

5. The encoding method as claimed in claim 1, wherein

the plural input audio signals are right-channel and left-channel signals of an acoustic signal.

6. The encoding method as claimed in claim 5, wherein

said step of splitting generates plural lower frequency signals and higher frequency signals from right-channel and left-channel signals of the acoustic signal.

7. The encoding method as claimed in claim 5, wherein

said step of splitting generates plural lower frequency signals and higher frequency signals from a signal generated based on the sum of the left-channel signal and the right-channel signal of said acoustic signal.

8. The encoding method as claimed in claim 1 further comprising the step of:

calculating weighting information for said higher frequency signals in association with each of the input audio signals, wherein

said step of generating generates signals encoded by said steps of encoding higher frequency signals and lower frequency signals, said encoding information and the weighting information.

9. The encoding method as claimed in claim 1, wherein

said step of slitting splits the signal derived from the plural input audio signals into plural band signals and generates plural the lower frequency signals and the higher frequency signals from the plural band signals;

said step of encoding low frequency signals forward orthogonally transforms said lower frequency signals to generate spectral signal components; and

said step of encoding high frequency signals forward orthogonally transforms said higher frequency signals to generate spectral signal components.

10. The encoding method as claimed in claim 9, further comprising the step of:

calculating weighting coefficient information for the higher frequency signals associated with the input audio signal, wherein

said step of generating a codestring generates a codestring based on the signal encoded by said steps of encoding the higher frequency signals and encoding the lower frequency signals, said encoding information and on the weighting information.

11. The encoding method as claimed in claim 1, wherein said step of encoding lower frequency signals encodes said plural lower frequency signals by different encoding systems.

12. An apparatus for encoding plural input audio signals, comprising:

splitting means for generating plural lower frequency signals and higher frequency signals from a signal derived from the plural input audio signals, wherein a number of the higher frequency signals is less than that of the plural input audio signals;

lower frequency encoding means for encoding each of said plural lower frequency signals;

higher frequency encoding means for encoding said higher frequency signals and for generating encoding information obtained by said higher frequency encoding means; and

generating means for generating a codestring based on signals encoded by said lower frequency encoding means and the higher frequency encoding means, and on said encoding information.

13. The encoding apparatus as claimed in claim 12, wherein said higher frequency encoding means normalizes and encodes the higher frequency signals, and also generates the encoding information, wherein the encoding information contains normalization coefficients based on said encoding of higher frequency signals.

14. The encoding apparatus as claimed in claim 13, wherein said splitting means generates from a signal derived from the plural input audio signals common higher frequency signals for said plural input audio signals, wherein

said higher frequency encoding means encodes the common higher frequency signals and generates the encoding information, wherein the encoding information contains normalization coefficient information based on the encoding of higher frequency signals.

15. The encoding apparatus as claimed in claim 12, wherein said splitting means generates common higher frequency signals for said plural input audio signals from the signal derived from the plural input audio signals.

16. The encoding apparatus as claimed in claim 12, wherein the plural input audio signals are right-channel and left-channel signals of an acoustic signal.

17. The encoding apparatus as claimed in claim 16, wherein said splitting means generates plural lower frequency signals and higher frequency signals from right-channel and left-channel signals of the acoustic signal.

18. The encoding apparatus as claimed in claim 16, wherein said splitting means generates plural lower frequency signals and higher frequency signals from a signal generated based on the sum of the left-channel signal and the right-channel signal of said acoustic signal.

19. The encoding apparatus as claimed in claim 12, further comprising:

weighting calculating means for calculating weighting information for said higher frequency signals in association with each of the input audio signals, wherein

said generating means generates signals encoded by said lower frequency encoding means and higher frequency encoding means, said encoding information and the weighting information.

20. The encoding apparatus as claimed in claim 12, wherein said splitting means splits the signal derived from the plural input audio signals into plural band signals and generates plural the lower frequency signals and the higher frequency signals from the plural band signals;

said lower frequency encoding means forward orthogonally transforms said lower frequency signals to generate spectral signal components; and

said higher frequency encoding means forward orthogonally transforms said higher frequency signals to generate spectral signal components.

21. The encoding apparatus as claimed in claim 20, further comprising:

a weighting calculating means for calculating weighting coefficient information for the higher frequency signals associated with the input audio signals, wherein

said generating means generates a codestring based on the signal encoded by said lower frequency encoding means and said higher frequency encoding means, said encoding information and on the weighting information.

22. The apparatus for encoding as claimed in claim 12, wherein said lower frequency encoding means encodes said plural lower frequency signals by different encoding systems.

23. A method for decoding a codestring, comprising the steps of:

separating a codestring having low-range codes obtained on encoding each of plural lower frequency signals, generated based on plural audio signals, high-range codes obtained on each of plural higher frequency signals wherein a number of higher frequency signals is smaller than that of the plural signals and encoding information obtained on encoding the higher frequency signals;

decoding the separated low-range codes;

decoding the separated high-range codes based on the encoding information; and

synthesizing plural output audio signals based on the decoded lower frequency signals and the decoded higher frequency signals.

24. The decoding method as claimed in claim 23, wherein said high-range decoding step decodes the high-range codes by denormalization based on normalization coefficient information contained in said encoding information.

25. The decoding method as claimed in claim 24, wherein said step of synthesizing generates plural output signals based on higher frequency signals decoded on denormalization by common normalization coefficients information for each of the higher frequency signals.

26. The decoding method as claimed in claim 23, wherein said step of synthesizing generates plural output signals using a common higher frequency signal decoded by the step of decoding the high-range codes and the plural lower frequency signals.

27. The decoding method as claimed in claim 23, wherein said step of synthesizing generates right-channel and left-channel signals of an acoustic signal based on the decoded lower frequency signals and the decoded higher frequency side signals.

28. The decoding method as claimed in claim 27, wherein said step of synthesizing synthesizes the decoded lower frequency signals and the decoded higher frequency signals to generate right-channel and left-channel signals of the acoustic signal.

29. The decoding method as claimed in claim 27, wherein said step of synthesizing generates right-channel and left-channel signals of the acoustic signals from a signal generated based on the sum of the decoded respective lower frequency signals, a signal generated based on the difference of the respective frequency signals and the decoded higher frequency signals.

30. The decoding method as claimed in claim 23 further comprising the step of:

generating weighting information used for controlling a level of the higher frequency signals corresponding to said plural signals, wherein

said step of synthesizing generates the output audio signals based on the decoded lower frequency signals and on the higher frequency signals controlled in level based on the weighting information.

31. The decoding method as claimed in claim 23, wherein

said step of synthesizing generates plural output signals based on the decoded lower frequency signals and on the higher frequency signals controlled in level based on weighting information contained in said encoding information.

32. The decoding method as claimed in claim 23, wherein

said step of synthesizing inverse orthogonally transforms lower frequency spectral signal components derived from the decoded respective lower frequency signals;

and

said step of synthesizing also inverse orthogonally transforms higher frequency spectral signal components derived from the decoded higher frequency signals.

33. The decoding method as claimed in claim 23, wherein said plural low-range codes are decoded by respective decoding methods.

34. An apparatus for decoding a codestring, comprising:

separating means for separating a codestring having low-range codes obtained on encoding each of plural lower frequency signals, generated based on plural audio signals, high-range codes obtained on each of plural higher frequency signals, wherein a number of higher frequency signals is smaller than that of the plural signals and encoding information obtained on encoding the high-range signals;

lower frequency decoding means for decoding the separated low-range codes;

higher frequency decoding means for decoding the separated high-range codes based on the encoding information; and

synthesis means for generating plural output audio signals based on the decoded lower frequency signals and the decoded higher frequency signals.

35. The decoding apparatus as claimed in claim 34, wherein said high-range decoding means decodes the high-range codes by denormalization based on normalization coefficient information contained in said encoding information.

36. The decoding apparatus as claimed in claim 35, wherein said synthesis means generates plural output signals based on higher frequency signals decoded on denormalization by common normalization coefficient information for each of the higher frequency signals.

37. The decoding apparatus as claimed in claim 34, wherein said synthesis means generates an plural output signals using the a common higher frequency signal decoded by the step of decoding the high-range codes and the plural lower frequency signals.

38. The decoding apparatus as claimed in claim 34, wherein said synthesis means generates right-channel and left-channel signals of an acoustic signal based on the decoded lower frequency signals and the decoded higher frequency signals.

39. The decoding apparatus as claimed in claim 38, wherein said synthesis means synthesizes the decoded lower frequency signals and the decoded higher frequency signals to generate right-channel and left-channel signals of the acoustic signal.

40. The decoding apparatus as claimed in claim 38, wherein said synthesis means generates right-channel and left-channel signals of the acoustic signal from a signal generated based on the sum of the decoded respective lower frequency signals, a signal generated based on the difference of the respective lower frequency signals and the decoded higher frequency signals.

41. The decoding apparatus as claimed in claim 34 further comprising:

weighted information generating means for generating weighting information used for controlling a level of the higher frequency signals corresponding to said plural signals, wherein

said synthesis means generates the output audio signals based on the decoded lower frequency signals and on the higher frequency signals controlled in level based on the weighting information.

42. The decoding apparatus as claimed in claim 34, wherein said synthesis means generates plural output signals based on the decoded lower frequency signals and on the higher frequency signals controlled in level based on weighting information contained in said encoding information.

43. The decoding apparatus as claimed in claim 34, wherein said synthesis means inverse orthogonally transforms lower frequency spectral signal components derived from the decoded respective lower frequency signals;

and

said synthesis means also inverse orthogonally transforms higher frequency spectral signal components derived from the decoded higher frequency signals.

44. The decoding apparatus as claimed in claim 34, wherein said plural low-range codes are decoded by respective decoding methods.

45. A recording medium having plural audio signals recorded thereon, the plural audio signals represented by

a codestring having low-range codes obtained on encoding each of plural lower frequency signals, high-range codes obtained on encoding a number of higher frequency signals and encoding information obtained on encoding the higher frequency signals,

wherein the lower frequency signals and the higher frequency signals are generated based on plural audio signals and a number of the higher frequency signals is smaller than that of the plural audio signals.

46. The recording medium as claimed in claim 45, wherein said encoding information includes normalization coefficient information obtained on normalization of said higher frequency signals.

47. The recording medium as claimed in claim 45, wherein said encoding information includes weighting information used for controlling a level of the higher frequency signals corresponding to the plural audio signals.

48. The recording medium as claimed in claim 45, wherein common high-range codes for the plural signals and the encoding information are recorded for said plural audio signals.

49. An apparatus for encoding plural input audio signals, comprising:

a circuit for generating plural lower frequency signals and higher frequency signals from a signal derived from the plural input audio signals, wherein a number of the higher frequency signals is less than that of the plural input audio signals;

a lower frequency encoder for encoding each of said plural lower frequency signals;

a higher frequency encoder for encoding said higher frequency signals and for generating encoding information obtained by said higher frequency encoder; and

a coder for generating a codestring based on signals encoded by said lower frequency encoder and the higher frequency encoder, and on said encoding information.

50. The encoding apparatus as claimed in claim 49, wherein said higher frequency encoder normalizes and encodes the higher frequency signals and also generates the encoding information, wherein the encoding information contains normalization coefficients based on said encoding of higher frequency signals.

51. The encoding apparatus as claimed in claim 50, wherein said circuit generates from a signal derived from the plural input audio signals common higher frequency signals for said plural input audio signals, wherein

said higher frequency encoder encodes the common higher frequency signals and generates the encoding information, wherein the encoding information contains normalization coefficient information based on the encoding of higher frequency signals.

52. The encoding apparatus as claimed in claim 49, wherein said circuit generates common higher frequency signals for said plural input audio signals from the signal derived from the plural input audio signals.

53. The encoding apparatus as claimed in claim 49, wherein the plural input audio signals are right-channel and left-channel signals of an acoustic signal.

54. The encoding apparatus as claimed in claim 53, wherein said circuit generates plural lower frequency signals and higher frequency signals from right-channel and left-channel signals of the acoustic signal.

55. The encoding apparatus as claimed in claim 53, wherein said circuit generates plural lower frequency signals and higher frequency signals from a signal generated based on the sum of the left-channel signal and the right-channel signal of said acoustic signal.

56. The encoding apparatus as claimed in claim 49, further comprising:

a calculator for calculating weighting information for said higher frequency signals in association with each of the input audio signals, wherein

said coder generates signals encoded by said lower frequency encoder and higher frequency encoder, said encoding information and the weighting information.

57. The encoding apparatus as claimed in claim 49, wherein

said circuit splits the signal derived from the plural input audio signals into plural band signals and generates plural the lower frequency signals and the higher frequency signals from the plural band signals;

said lower frequency encoder forward orthogonally transforms said lower frequency signals to generate spectral signal components; and

said higher frequency encoder forward orthogonally transforms said higher frequency signals to generate spectral signal components.

58. The encoding apparatus as claimed in claim 57, further comprising:

a calculator for calculating weighting coefficient information for the higher frequency signals associated with the input audio signals, wherein

said coder generates a codestring based on the signal encoded by said lower frequency encoder and said higher frequency encoder, said encoding information and on the weighting information.

59. The apparatus for encoding as claimed in claim 49, wherein said lower frequency encoder encodes said plural lower frequency signals by different encoding systems.

60. An apparatus for decoding a codestring, comprising:

a circuit for separating a codestring having low-range codes obtained on encoding each of plural lower frequency signals, generated based on plural audio signals, high-range codes obtained on each of plural higher frequency signals, wherein a number of higher frequency signals is smaller than that of the plural signals and encoding information obtained on encoding the high-range signals;

lower frequency decoder for decoding the separated low-range codes;

higher frequency decoder for decoding the separated high-range codes based on the encoding information; and

a synthesizer for generating plural output audio signals based on the decoded lower frequency signals and the decoded higher frequency signals.

61. The decoding apparatus as claimed in claim 60, wherein said high-range decoder decodes the high-range codes by denormalization based on normalization coefficient information contained in said encoding information.

62. The decoding apparatus as claimed in claim 61, wherein said synthesizer generates plural output signals based on higher frequency signals decoded on denormalization by common normalization coefficient information for each of the higher frequency signals.

63. The decoding apparatus as claimed in claim 60, wherein said synthesizer generates an plural output signals using the a common higher frequency signal decoded by the step of decoding the high-range codes and the plural lower frequency signals.

64. The decoding apparatus as claimed in claim 60, wherein said synthesizer generates right-channel and left-channel signals of an acoustic signal based on the decoded lower frequency signals and the decoded higher frequency signals.

65. The decoding apparatus as claimed in claim 64, wherein said synthesizer synthesizes the decoded lower frequency signals and the decoded higher frequency signals to generate right-channel and left-channel signals of the acoustic signal.

66. The decoding apparatus as claimed in claim 64, wherein said synthesizer generates right-channel and left-channel signals of the acoustic signal from a signal generated based on the sum of the decoded respective lower frequency signals, a signal generated based on the difference of the respective lower frequency signals and the decoded higher frequency signals.

67. The decoding apparatus as claimed in claim 60, wherein the circuit is a first circuit, further comprising:

a second circuit for generating weighting information used for controlling a level of the higher frequency signals corresponding to said plural signals, wherein

said synthesizer generates the output audio signals based on the decoded lower frequency signals and on the higher frequency signals controlled in level based on the weighting information.

68. The decoding apparatus as claimed in claim 60, wherein said synthesizer generates plural output signals based on the decoded lower frequency signals and on the higher frequency signals controlled in level based on weighting information contained in said encoding information.

69. The decoding apparatus as claimed in claim 60, wherein said synthesizer inverse orthogonally transforms lower frequency spectral signal components derived from the decoded respective lower frequency signals;

and

said synthesizer also inverse orthogonally transforms higher frequency spectral signal components derived from the decoded higher frequency signals.

70. The decoding apparatus as claimed in claim 60, wherein said plural low-range codes are decoded by respective decoding methods.