Digital audio watermarking using content-adaptive, multiple echo hopping

• US 6,674,861 B1
• Filed: 12/02/1999
• Issued: 01/06/2004
• Est. Priority Date: 12/29/1998
• Status: Expired due to Fees

• Current Assignee: Kent Ridge Digital Labs
• Original Assignee: Kent Ridge Digital Labs
• Inventors: Xin, Kai, Li, Haizhou, Xu, Changsheng, Wu, Jiankang, Sun, Qibin
• Primary Examiner(s): Peeso, Thomas R.
• Application Number:
  US09/445,141
• Time in Patent Office: 1,496 Days
• Field of Search: 380/252, 380/264, 380/277, 380/278, 380/283
• US Class Current: 380/252
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal

Abstract

A method, an apparatus and a computer program product for adaptive, content-based watermark embedding of a digital audio signal (100) are disclosed. Corresponding watermark extracting techniques are also disclosed. Watermark information (102) is encrypted (120) using an audio digest signal, i.e. a watermark key (108). To optimally balance inaudibility and robustness when embedding and extracting watermarks (450), the original audio signal (100) is divided into fixed-length frames (1100, 1120, 1130) in the time domain. Echoes (S′[n], S″[n]) are embedded in the original audio signal (100) to represent the watermark (450). The watermark (450) is generated by delaying and scaling the original audio signal (100) and embedding it in the audio signal (100). An embedding scheme (104) is designed for each frame (1100, 1120, 1130) according to its properties in the frequency domain. Finally, a multiple-echo hopping module (160) is used to embed and extract watermarks in the frame (1100, 1120, 1130) of the audio signal (100). An audio watermarking system known as KentMark (Audio) is implemented.

Claims

1. A method of embedding a watermark in a digital audio signal, said method including the steps of:

embedding at least one echo dependent upon said watermark in a portion of said digital audio signal, predefined characteristics of said at least one echo being dependent upon time and/or frequency domain characteristics of said portion of said digital audio signal to provide a substantially inaudible and robust embedded watermark in said digital audio signal.

2. The method according to claim 1, further including the step of digesting said digital audio signal to provide a watermark key, said watermark being dependent upon said watermark key.

3. The method according to claim 2, further including the step of encrypting predetermined information using said watermark key to form said watermark.

4. The method according to claim 1, further including the step of generating said at least one echo to have a delay and an amplitude relative to said digital audio signal that is substantially inaudible.

5. The method according to claim 1, wherein the value of said delay and said amplitude are programmable.

6. The method according to claim 1, wherein two or more echoes are programmably sequenced having different delays and/or amplitudes.

7. The method according to claim 1, wherein two portions of said digital audio signal are embedded with different echoes dependent upon the time and/or frequency characteristics of said digital audio signal.

8. An apparatus for embedding a watermark in a digital audio signal, said apparatus including:

means for determining time and/or frequency domain characteristics of said digital audio signal;

means for embedding at least one echo dependent upon said watermark in a portion of said digital audio signal, predefined characteristics of said at least one echo being dependent upon said time and/or frequency domain characteristics of said portion of said digital audio signal to provide a substantially inaudible and robust embedded watermark in said digital audio signal.

9. The apparatus according to claim 8, further including means for digesting said digital audio signal to provide a watermark key, said watermark being dependent upon said watermark key.

10. The apparatus according to claim 9, further including means for encrypting predetermined information using said watermark key to form said watermark.

11. The apparatus according to claim 8, further including means for generating said at least one echo to have a delay and an amplitude relative to said digital audio signal that is substantially inaudible.

12. The apparatus according to claim 8, wherein the value of said delay and said amplitude are programmable.

13. The apparatus according to claim 8, wherein two or more echoes are programmably sequenced having different delays and/or amplitudes.

14. The apparatus according to claim 8, wherein two portions of said digital audio signal are embedded with different echoes dependent upon the time and/or frequency characteristics of said digital audio signal.

15. A computer program product having a computer readable medium having a computer program recorded therein for embedding a watermark in a digital audio signal, said computer program product including:

means for determining time and/or frequency domain characteristics of said digital audio signal;

means for embedding at least one echo dependent upon said watermark in a portion of said digital audio signal, predefined characteristics of said at least one echo being dependent upon said time and/or frequency domain characteristics of said portion of said digital audio signal to provide a substantially inaudible and robust embedded watermark in said digital audio signal.

16. The computer program product according to claim 15, further including means for digesting said digital audio signal to provide a watermark key, said watermark being dependent upon said watermark key.

17. The computer program product according to claim 16, further including means for encrypting predetermined information using said watermark key to form said watermark.

18. The computer program product according to claim 15, further including means for generating said at least one echo to have a delay and an amplitude relative to said digital audio signal that is substantially inaudible.

19. The computer program product according to claim 15, wherein the value of said delay and said amplitude are programmable.

20. The computer program product according to claim 15, wherein two or more echoes are programmably sequenced having different delays and/or amplitudes.

21. The computer program product according to claim 15, wherein two portions of said digital audio signal are embedded with different echoes dependent upon the time and/or frequency characteristics of said digital audio signal.

22. A method of extracting a watermark from a watermarked digital audio signal, said method including the steps of:

detecting at least one echo embedded in a portion of said watermarked digital audio signal, predefined characteristics of said at least one echo being dependent upon time and/or frequency domain characteristics of said portion of a corresponding original digital audio signal; and

decoding said at least one detected echo recover said watermark.

23. The method according to claim 22, further including the step of registering said watermarked digital audio signal with said original audio signal to recover from any distortions and/or modifications of said watermarked digital audio signal.

24. The method according to claim 22, wherein said decoding step is dependent upon an embedding scheme.

25. The method according to claim 22, further comprising the step of decrypting one or more codes produced by said decoding step dependent upon a digested digital audio signal.

26. The method according to claim 22, wherein said at least one echo has a delay and an amplitude relative to said digital audio signal that is substantially inaudible.

27. The method according to claim 26, wherein the value of said delay and said amplitude are programmable.

28. The method according to claim 22, wherein two or more echoes are programmably sequenced having different delays and/or amplitudes.

29. The method according to claim 22, wherein two portions of said watermarked digital audio signal is embedded with different echoes dependent upon the time and/or frequency characteristics of said original digital audio signal.

30. An apparatus for extracting a watermark from a watermarked digital audio signal, said apparatus including:

means for detecting at least one echo embedded in a portion of said watermarked digital audio signal, predefined characteristics of said at least one echo being dependent upon time and/or frequency domain characteristics of said portion of a corresponding original digital audio signal; and

means for decoding said at least one detected echo recover said watermark.

31. The apparatus according to claim 30, further means for registering said watermarked digital audio signal with said original audio signal to recover from any distortions and/or modifications of said watermarked digital audio signal.

32. The apparatus according to claim 30, wherein said decoding means is dependent upon an embedding scheme.

33. The apparatus according to claim 30, further comprising means for decrypting one or more codes produced by said decoding step dependent upon a digested digital audio signal.

34. The apparatus according to claim 30, wherein said at least one echo has a delay and an amplitude relative to said digital audio signal that is substantially inaudible.

35. The apparatus according to claim 34, wherein the value of said delay and said amplitude are programmable.

36. The apparatus according to claim 30, wherein two or more echoes are programmably sequenced having different delays and/or amplitudes.

37. The apparatus according to claim 30, wherein two portions of said watermarked digital audio signal is embedded with different echoes dependent upon the time and/or frequency characteristics of said original digital audio signal.

38. A computer program product having a computer readable medium having a computer program recorded therein for extracting a watermark from a watermarked digital audio signal, said computer program product including:

means for detecting at least one echo embedded in a portion of said watermarked digital audio signal, predefined characteristics of said at least one echo being dependent upon time and/or frequency domain characteristics of said portion of a corresponding original digital audio signal; and

means for decoding said at least one detected echo recover said watermark.

39. The computer program product according to claim 38, further means for registering said watermarked digital audio signal with said original audio signal to recover from any distortions and/or modifications of said watermarked digital audio signal.

40. The computer program product according to claim 38, wherein said decoding means is dependent upon an embedding scheme.

41. The computer program product according to claim 38, further comprising means for decrypting one or more codes produced by said decoding step dependent upon a digested digital audio signal.

42. The computer program product according to claim 38, wherein said at least one echo has a delay and an amplitude relative to said digital audio signal that is substantially inaudible.

43. The computer program product according to claim 42, wherein the value of said delay and said amplitude are programmable.

44. The computer program product according to claim 38, wherein two or more echoes are programmably sequenced having different delays and/or amplitudes.

45. The computer program product according to claim 38, wherein two portions of said watermarked digital audio signal is embedded with different echoes dependent upon the time and/or frequency characteristics of said original digital audio signal.

46. A method of embedding a watermark in a digital audio signal, said method including the steps of:

generating a digital watermark;

adaptively segmenting said digital audio signal dependent upon at least one frequency and/or time domain characteristic into two or more frames containing respective portions of said digital audio signal;

classifying each frame dependent upon at least one frequency and/or time domain characteristic of said portion of said digital audio signal in said frame; and

embedding at least one echo in at least one of said frames, said echo being dependent upon said watermark and upon a classification of each frame determined by said classifying step, whereby a watermarked digital audio signal is produced.

47. The method according to claim 46, wherein said watermark is dependent upon said digital audio signal.

48. The method according to claim 47, further including the steps of:

audio digesting said digital audio signal to provide an audio digest; and

encrypting watermark information dependent upon said audio digest.

49. The method according to claim 46, further including the step of extracting one or more features from each frame of said digital audio signal.

50. The method according to claim 49, further including the step of selecting an embedding scheme for each frame dependent upon said classification of each frame, said embedding scheme adapted dependent upon at least one time and/or frequency domain characteristic of said classification for the corresponding portion of said digital audio signal.

51. The method according to claim 50, further including the step of embedding said at least one echo in at least one of said frames dependent upon the selected embedding scheme.

52. The method according to claim 51, wherein the amplitude and the delay of said echo relative to the corresponding portion of said digital audio signal in said frame is defined dependent upon the embedding scheme so as to be inaudible.

53. The method according to claim 52, wherein at least two echoes are embedded in said frame.

54. The method according to claim 46, wherein two or more echoes embedded in said digital audio signal are dependent upon a bit of said watermark.

55. An apparatus for embedding a watermark in a digital audio signal, said apparatus including:

means for generating a digital watermark;

means for adaptively segmenting said digital audio signal dependent upon at least one frequency and/or time domain characteristic into two or more frames containing respective portions of said digital audio signal;

means for classifying each frame dependent upon at least one frequency and/or time domain characteristic of said portion of said digital audio signal in said frame; and

means for embedding at least one echo in at least one of said frames, said echo being dependent upon said watermark and upon a classification of each frame determined by said classifying means, whereby a watermarked digital audio signal is produced.

56. The apparatus according to claim 55, wherein said watermark is dependent upon said digital audio signal.

57. The apparatus according to claim 56, further including:

means for audio digesting said digital audio signal to provide an audio digest; and

means for encrypting watermark information dependent upon said audio digest.

58. The apparatus according to claim 55, further including means for extracting one or more features from each frame of said digital audio signal.

59. The apparatus according to claim 58, further including means for selecting an embedding scheme for each frame dependent upon said classification of each frame, said embedding scheme adapted dependent upon at least one time and/or frequency domain characteristic of said classification for the corresponding portion of said digital audio signal.

60. The apparatus according to claim 59, further including means for embedding said at least one echo in at least one of said frames dependent upon the selected embedding scheme.

61. The apparatus according to claim 60, wherein the amplitude and the delay of said echo relative to the corresponding portion of said digital audio signal in said frame is defined dependent upon the embedding scheme so as to be inaudible.

62. The apparatus according to claim 61, wherein at least two echoes are embedded in said frame.

63. The apparatus according to claim 55, wherein two or more echoes embedded in said digital audio signal are dependent upon a bit of said watermark.

64. A computer program product having a computer readable medium having a computer program recorded therein for embedding a watermark in a digital audio signal, said computer program product including:

means for generating a digital watermark;

means for adaptively segmenting said digital audio signal dependent upon at least one frequency and/or time domain characteristic into two or more frames containing respective portions of said digital audio signal;

means for classifying each frame dependent upon at least one frequency and/or time domain characteristic of said portion of said digital audio signal in said frame; and

means for embedding at least one echo in at least one of said frames, said echo being dependent upon said watermark and upon a classification of each frame determined by said classifying means, whereby a watermarked digital audio signal is produced.

65. The computer program product according to claim 64, wherein said watermark is dependent upon said digital audio signal.

66. The computer program product according to claim 65, further including:

means for audio digesting said digital audio signal to provide an audio digest; and

means for encrypting watermark information dependent upon said audio digest.

67. The computer program product according to claim 64, further including means for extracting one or more features from each frame of said digital audio signal.

68. The computer program product according to claim 67, further including means for selecting an embedding scheme for each frame dependent upon said classification of each frame, said embedding scheme adapted dependent upon at least one time and/or frequency domain characteristic of said classification for the corresponding portion of said digital audio signal.

69. The computer program product according to claim 68, further including means for embedding said at least one echo in at least one of said frames dependent upon the selected embedding scheme.

70. The computer program product according to claim 69, wherein the amplitude and the delay of said echo relative to the corresponding portion of said digital audio signal in said frame is defined dependent upon the embedding scheme so as to be inaudible.

71. The computer program product according to claim 70, wherein at least two echoes are embedded in said frame.

72. The computer program product according to claim 64, wherein two or more echoes embedded in said digital audio signal are dependent upon a bit of said watermark.

73. A method of extracting a watermark from a watermarked digital audio signal, said method including the steps of:

adaptively segmenting said watermarked digital audio signal into two or more frames containing corresponding portions of said watermarked digital audio signal;

detecting at least one echo present in said frames; and

code mapping said at least one detected echo to extract an embedded watermark, said mapping being dependent upon one or more embedding schemes used to embed said at least one echo in said watermarked digital audio signal.

74. The method according to claim 73, further including the step of audio registering said watermarked digital audio signal with said original digital audio signal to determine any unauthorised modifications of said watermarked digital audio signal.

75. The method according to claim 73, further including the step of decrypting said embedded watermark dependent upon an audio digest signal to derive watermark information, said audio digest signal being dependent upon an original digital audio signal.

76. An apparatus for extracting a watermark from a watermarked digital audio signal, said apparatus including:

means for adaptively segmenting said watermarked digital audio signal into two or more frames containing corresponding portions of said watermarked digital audio signal;

means for detecting at least one echo present in said frames; and

means for code mapping said at least one detected echo to extract an embedded watermark, said mapping being dependent upon one or more embedding schemes used to embed said at least one echo in said watermarked digital audio signal.

77. The apparatus according to claim 76, further including means for audio registering said watermarked digital audio signal with said original digital audio signal to determine any unauthorised modifications of said watermarked digital audio signal.

78. The apparatus according to claim 76, further including means for decrypting said embedded watermark dependent upon an audio digest signal to derive watermark information, said audio digest signal being dependent upon an original digital audio signal.

79. A computer program product having a computer readable medium having a computer program recorded therein for extracting a watermark from a watermarked digital audio signal, said computer program product including:

means for adaptively segmenting said watermarked digital audio signal into two or more frames containing corresponding portions of said watermarked digital audio signal;

means for detecting at least one echo present in said frames; and

means for code mapping said at least one detected echo to extract an embedded watermark, said mapping being dependent upon one or more embedding schemes used to embed said at least one echo in said watermarked digital audio signal.

80. The computer program product according to claim 79, further including means for audio registering said watermarked digital audio signal with said original digital audio signal to determine any unauthorised modifications of said watermarked digital audio signal.

81. The computer program product according to claim 79, further including means for decrypting said embedded watermark dependent upon an audio digest signal to derive watermark information, said audio digest signal being dependent upon an original digital audio signal.