Methods for audio watermarking and decoding

• US 7,536,555 B2
• Filed: 01/03/2006
• Issued: 05/19/2009
• Est. Priority Date: 11/18/1993
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Primary Examiner(s): Smithers; Matthew B
• Assistant Examiner(s): Pyzocha; Michael
• Application Number:
  US11/325,131
• Publication Number:
  US 20060109984A1
• Time in Patent Office: 1,232 Days
• Field of Search: 713/176, 726/30, 726/32
• US Class Current: 713/176
• CPC Class Codes: G06Q 20/1235 with control of digital rights management [DRM]
• CPC Class Codes: G06Q 20/306 using TV related infrastructures external card used for payment with client device H04N21/4185
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/40145 Biometric identity checks
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0057 Compression invariant watermarking
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G07C 9/253 visually
• CPC Class Codes: G07D 7/0032 using holograms
• CPC Class Codes: G07D 7/004 using digital security elements, e.g. information coded on a magnetic thread or strip
• CPC Class Codes: G07F 17/26 for printing, stamping, franking, typing or teleprinting apparatus ticket printing or the like apparatus G07F17/42
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/086 by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G07F 7/1016 Devices or methods for securing the PIN and other transaction-data, e.g. by encryption arrangements for secret communication, see H04L9/00
• CPC Class Codes: G07F 7/12 Card verification
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G10L 19/022 Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00094 : involving measures which result in a restriction to authorised record carriers
• CPC Class Codes: G11B 20/00115 : wherein the record carrier stores a unique medium identifier
• CPC Class Codes: G11B 20/00166 : involving measures which result in a restriction to authorised contents recorded on or reproduced from a record carrier, e.g. music or software
• CPC Class Codes: G11B 20/00181 : using a content identifier, e.g. an international standard recording code [ISRC] or a digital object identifier [DOI]
• CPC Class Codes: G11B 20/0021 : involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00231 : wherein the key is obtained from a local external medium, e.g. a card
• CPC Class Codes: G11B 20/00492 : wherein content or user data is encrypted
• CPC Class Codes: G11B 20/00884 : involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: G11B 20/00891 : embedded in audio data
• CPC Class Codes: H04B 1/665 : using psychoacoustic properties of the ear, e.g. masking effect
• CPC Class Codes: H04N 1/00005 : relating to image data
• CPC Class Codes: H04N 1/00037 : Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00079 : remotely
• CPC Class Codes: H04N 1/32128 : attached to the image data, e.g. file header, transmitted message header, information on the same page or in the same computer file as the image for information embedded in the image H04N1/32144
• CPC Class Codes: H04N 1/32144 : embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32203 : Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 : involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32229 : with selective or adaptive application of the additional information, e.g. in selected regions of the image H04N1/32213 takes precedence
• CPC Class Codes: H04N 1/32251 : in multilevel data, e.g. greyscale or continuous tone data
• CPC Class Codes: H04N 1/32288 : Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image
• CPC Class Codes: H04N 2005/91321 : the copy protection signal being a copy protection control signal, e.g. a record inhibit signal
• CPC Class Codes: H04N 2005/91335 : the copy protection signal being a watermark
• CPC Class Codes: H04N 2201/3205 : of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• CPC Class Codes: H04N 2201/3207 : of an address
• CPC Class Codes: H04N 2201/3225 : of data relating to an image, a page or a document
• CPC Class Codes: H04N 2201/3226 : of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• CPC Class Codes: H04N 2201/3233 : of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3246 : of data relating to permitted access or usage, e.g. level of access or usage parameters for digital rights management [DRM] related to still images
• CPC Class Codes: H04N 2201/3249 : data relating to a linked page or object, e.g. hyperlink
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3271 : Printing or stamping
• CPC Class Codes: H04N 2201/3278 : Transmission
• CPC Class Codes: H04N 2201/328 : Processing of the additional information
• CPC Class Codes: H04N 5/913 : for scrambling ; for copy protection
• CPC Class Codes: H04N 7/08 : Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band , e.g. by time division H04N7/007 takes precedence

Abstract

The present invention relates generally to digital watermarking and steganographic embedding and decoding. One claim recites a method of decoding auxiliary data that has been embedded in an audio signal through modifications to the audio signal that are substantially imperceptible. The auxiliary data comprises bits of digital data and the bits being carried in a plurality of embedded code signals embedded in the audio signal, each of the plurality of embedded code signals corresponding to one or more bits in the auxiliary data. The method includes: extracting auxiliary data from a series of blocks of the audio signal, the blocks conveying the same auxiliary data, yet the blocks representing the auxiliary data differently as the embedded code signals conveying the same auxiliary data change over the blocks, and wherein extracting includes evaluating features of the blocks, the features being modulated to carry the auxiliary data; and using the auxiliary data from the series of blocks to increase statistical confidence of accurate recovery of the auxiliary data, the auxiliary data being separately decoded from the blocks and combined to increase the statistical confidence of recovery of the auxiliary data. Of course, other claims and combinations are provided as well.

Claims

1. A method of decoding auxiliary data that has been embedded in an audio signal through modifications to the audio signal that are substantially imperceptible, the auxiliary data comprises bits of digital data and the bits being carried in a plurality of embedded code signals embedded in the audio signal, each of the plurality of embedded code signals corresponding to one or more bits in the auxiliary data, the method comprising:

utilizing a multi-purpose processor programmed as an auxiliary data decoder, extracting auxiliary data from a series of blocks of the audio signal, the blocks conveying the same auxiliary data, yet the blocks represent the auxiliary data differently as the embedded code signals conveying the same auxiliary data change over the blocks, and in which the extracting includes utilizing the multi-purpose processor programmed as the auxiliary data decoder to evaluate features of the blocks, the features being modulated to carry the auxiliary data; and

using the auxiliary data from the series of blocks to increase statistical confidence of accurate recovery of the auxiliary data, the auxiliary data being separately decoded from the blocks and combined to increase the statistical confidence of recovery of the auxiliary data.

2. The method of claim 1 including using reference data to calibrate detection of the auxiliary data.

3. The method of claim 2 wherein the reference data comprises a predetermined pseudorandom sequence.

4. The method of claim 1 wherein the features comprise signal power calculated from the blocks.

5. The method of claim 1 wherein auxiliary data is conveyed using pseudo random carrier data.

6. The method of claim 5 wherein the pseudorandom carrier data is previously used to modify the features of the blocks to embed the auxiliary data in the blocks.

7. A programmed computing device storing instructions in memory, said instructions are executable by said programmed computing device to perform the acts of claim 1.

8. A computer readable media comprising instructions stored thereon to cause a multi-purpose processor to perform the acts of claim 1.

9. The method of claim 1 further comprising obtaining the audio signal with a microphone, the audio signal representing an ambient audio signal carried by sound waves.

10. A method of processing a digital audio signal comprising:

utilizing a multi-purpose processor programmed as a steganographic encoder to perform the acts;

altering the digital audio signal in accordance with an embedded signal so as to encode an auxiliary code therein;

the digital audio signal, the altered audio signal, and the embedded signal each including a number of elements, each with an associated value, wherein an element of the altered audio signal has a value different than that of corresponding elements in both the digital audio and embedded signals, and wherein the auxiliary code and reference data are used to generate the embedded signal, the association between the embedded signal and the auxiliary code being indiscernible without availability of the reference data;

modifying a feature of the audio signal using the reference data according to the auxiliary code to generate the embedded signal;

adjusting the embedded signal according to characteristics of the digital audio signal such that the altered signal preserves aural information of the digital audio signal without human perceptible degradation; and

repeating the auxiliary data in blocks of the audio signal, the blocks conveying the same auxiliary data, yet the blocks representing the auxiliary data differently as time varying embedded code signals conveying the same auxiliary data change over time in different blocks of the audio signal, wherein auxiliary data is separately decodable from the blocks of audio data using the time-varying embedded code signals.

11. The method of claim 10 including providing calibration data in the embedded signal to facilitate decoding of the auxiliary code from the altered signal.

12. The method of claim 11 wherein the calibration data comprises a pseudorandom signal.

13. The method of claim 10 including embedding the auxiliary code in the audio signal repeatedly such that recovery of the auxiliary code from the altered audio signal is improved by combining elements of the embedded signal in a process of decoding the auxiliary code.

14. A computer readable media comprising instructions stored thereon to cause a multi-purpose processor to perform the acts of claim 10.

15. A programmed computing device storing instructions in memory, said instructions are executable by said programmed computing device to perform the acts of claim 10.

16. An apparatus comprising:

electronic memory; and

electronic processing circuitry for decoding auxiliary data that has been embedded in an audio signal through modifications to the audio signal that are substantially imperceptible, the auxiliary data comprises bits of digital data and the bits being carried in a plurality of embedded code signals embedded in the audio signal, each of the plurality of embedded code signals corresponding to one or more bits in the auxiliary;

electronic processing circuitry for extracting auxiliary data from a series of blocks of the audio signal, the blocks conveying the same auxiliary data, yet the blocks represent the auxiliary data differently as the embedded code signals conveying the same auxiliary data changes over the blocks, and wherein the extracting includes evaluating features of the blocks, the features being modulated to carry the auxiliary data; and

electronic processing circuitry operable to use the auxiliary data from the series of blocks to increase statistical confidence of accurate recovery of the auxiliary data, the auxiliary data being separately decoded from the blocks and combined to increase the statistical confidence of recovery of the auxiliary data;

in which said electronic processing circuitry is in a state of execution performing at least one of the above functions.

17. The apparatus of claim 16 in which the electronic processing circuitry is further operable to use reference data to calibrate detection of the auxiliary data.

18. The apparatus of claim 17 in which the reference data comprises a predetermined pseudorandom sequence.

19. The apparatus of claim 16 in which the features comprise signal power calculated from the blocks.

20. The apparatus of claim 16 in which auxiliary data is conveyed using pseudo random carrier data.

21. The apparatus of claim 20 in which the pseudorandom carrier data is previously used to modify the features of the blocks to embed the auxiliary data in the blocks.

22. The apparatus of claim 16 in which the electronic memory comprises data stored therein, the data representing the embedded audio signal.

23. An apparatus comprising:

electronic memory; and

a multi-purpose computer processor programmed to;

alter a digital audio signal in accordance with an embedded signal so as to encode an auxiliary code therein;

the digital audio signal, the altered audio signal, and the embedded signal each including a number of elements, each with an associated value, wherein an element of the altered audio signal has a value different than that of corresponding elements in both the digital audio and embedded signals, and wherein the auxiliary code and reference data are used to generate the embedded signal, the association between the embedded signal and the auxiliary code being indiscernible without availability of the reference data;

modify a feature of the audio signal using the reference data according to the auxiliary code to generate the embedded signal;

adjust the embedded signal according to characteristics of the digital audio signal such that the altered signal preserves aural information of the digital audio signal without human perceptible degradation; and

repeat the auxiliary data in blocks of the audio signal, the blocks conveying the same auxiliary data, yet the blocks representing the auxiliary data differently as time varying embedded code signals conveying the same auxiliary data change over time in different blocks of the audio signal, wherein auxiliary data is separately decodable from the blocks of audio data using the time-varying embedded code signals.

24. The apparatus of claim 23 in which the multi-purpose computer processor is programmed to:

provide calibration data in the embedded signal to facilitate decoding of the auxiliary code from the altered signal.

25. The apparatus of claim 24 in which the calibration data comprises a pseudorandom signal.

26. The apparatus of claim 23 in which the multi-purpose computer processor is further programmed to:

embed the auxiliary code in the audio signal repeatedly such that recovery of the auxiliary code from the altered audio signal is improved by combining elements of the embedded signal in a process of decoding the auxiliary code.

27. The apparatus of claim 23 in which the electronic memory comprises data stored therein, the data representing the embedded audio signal.

28. The apparatus of claim 23 in which said multi-purpose computer processor is in a state of execution performing at least one function recited in claim 23.

29. An apparatus comprising:

electronic memory storing data representing an audio signal; and

electronic processing circuitry decoding auxiliary data from the data representing the audio signal, the auxiliary data having been embedded in the audio signal through modifications to the audio signal that are substantially imperceptible, the auxiliary data comprises bits of digital data and the bits being carried in a plurality of embedded code signals embedded in the audio signal, each of the plurality of embedded code signals corresponding to one or more bits in the auxiliary data,

the electronic processing circuitry also extracting auxiliary data from a series of blocks of the data representing the audio signal, the blocks conveying the same auxiliary data, yet the blocks represent the auxiliary data differently as the embedded code signals conveying the same auxiliary data change over the blocks, and in which the extracting includes evaluating features of the blocks, the features being modulated to carry the auxiliary data; and

the electronic processing circuitry also utilizing the auxiliary data from the series of blocks to increase statistical confidence of accurate recovery of the auxiliary data, the auxiliary data being separately decoded from the blocks and combined to increase the statistical confidence of recovery of the auxiliary data.

30. The apparatus of claim 29 wherein the electronic processing circuitry comprises recognition signal processing circuitry.

31. The apparatus of claim 29 further comprising a microphone to capture an audio signal, wherein the data corresponds the audio signal.

32. An apparatus comprising:

electronic memory storing data representing a digital audio signal; and

a multi-purpose processor programmed to;

alter the digital audio signal in accordance with an embedded signal so as to encode an auxiliary code therein;

the digital audio signal, the altered audio signal, and the embedded signal each including a number of elements, each with an associated value, wherein an element of the altered audio signal has a value different than that of corresponding elements of the altered audio signal and embedded signals, and in which the auxiliary code and reference data are used to generate the embedded signal, the association between the embedded signal and the auxiliary code being indiscernible without availability of the reference data;

modify a feature of the audio signal using the reference data according to the auxiliary code to generate the embedded signal;

adjust the embedded signal according to characteristics of the digital audio signal such that the altered signal preserves aural information of the digital audio signal without human perceptible degradation; and

repeat the auxiliary data in blocks of the audio signal, the blocks conveying the same auxiliary data, yet the blocks representing the auxiliary data differently as the time varying embedded code signals conveying the same auxiliary data change over time in different blocks of the audio signal, wherein auxiliary data is separately decodable from the blocks of audio data using the time-varying embedded code signals.

33. The apparatus of claim 32 in which the digital audio signal represents an audio signal carried by sound waves.

34. An apparatus comprising:

a microphone for capturing an audio signal carried by sound waves;

electronic memory for buffering a digital audio signal representing at least a portion of the audio signal captured by said microphone; and

a multi-purpose processor configured to;

decode auxiliary data from the digital audio signal, the auxiliary data having been embedded in the audio signal through modifications to the audio signal that are substantially imperceptible, the auxiliary data comprises bits of digital data and the bits being carried in a plurality of embedded code signals embedded in the audio signal, each of the plurality of embedded code signals corresponding to one or more bits in the auxiliary data;

extract auxiliary data from a series of blocks of the digital audio signal, the blocks conveying the same auxiliary data, yet the blocks represent the auxiliary data change over the blocks, and in which the function to extract includes evaluating features of the blocks, the features being modulated to carry the auxiliary data; and

utilize the auxiliary data from the series of blocks to increase statistical confidence of accurate recovery of the auxiliary data, the auxiliary data being separately decoded from the blocks and combined to increase the statistical confidence of recovery of the auxiliary data.

35. The apparatus of claim 34 in which said multi-purpose processor is in a state of execution to perform at least one of the recited functions.

36. The apparatus of claim 34 further comprising an analog-to-digital converter for converting audio signals carried by sound waves into digital audio signals.

37. An apparatus comprising:

a microphone for capturing an audio signal carried by sound waves;

electronic memory for buffering a digital audio signal representing at least a portion of the audio signal captured by said microphone; and

electronic processing circuitry configured to;

decode auxiliary data from the digital audio signal, the auxiliary data having been embedded in the audio signal through modifications to the audio signal that are substantially imperceptible, the auxiliary data comprises bits of digital data and the bits being carried in a plurality of embedded code signals embedded in the audio signal, each of the plurality of embedded code signals corresponding to one or more bits in the auxiliary data;

extract auxiliary data from a series of blocks of the digital audio signal, the blocks conveying the same auxiliary data, yet the blocks represent the auxiliary data differently as the embedded code signals conveying the same auxiliary data change over the blocks, and in which the function to extract includes evaluating features of the blocks, the features being modulated to carry the auxiliary data; and

utilize the auxiliary data from the series of blocks to increase statistical confidence of accurate recovery of the auxiliary data, the auxiliary data being separately decoded from the blocks and combined to increase the statistical confidence of recovery of the auxiliary data.

38. The apparatus of claim 37 in which said electronic processing circuitry is in a state of execution to perform at least one of the recited functions.

39. The apparatus of claim 37 further comprising an analog-to-digital converter for converting audio signals carried by sound waves into digital audio signals.

40. An apparatus comprising:

means for capturing an audio signal carried by sound waves;

means for buffering a digital audio signal representing at least a portion of the audio signal captured by said means for capturing; and

means for decoding auxiliary data from the digital audio signal, the auxiliary data having been embedded in the audio signal through modifications to the audio signal that are substantially imperceptible, the auxiliary data comprises bits of digital data and the bits being carried in a plurality of embedded code signals embedded in the audio signal, each of the plurality of embedded code signals corresponding to one or more bits in the auxiliary data;

means for extracting auxiliary data from a series of blocks of the digital audio signal, the blocks conveying the same auxiliary data, yet the blocks represent the auxiliary data differently as the embedded code signals conveying the same auxiliary data change over the blocks, and in which the extracting includes evaluating features of the blocks, the features being modulated to carry the auxiliary data; and

means for utilizing the auxiliary data from the series of blocks to increase statistical confidence of accurate recovery of the auxiliary data, the auxiliary data being separately decoded from the blocks and combined to increase the statistical confidence of recovery of the auxiliary data.

41. The apparatus of claim 40 further comprising means for converting audio signals carried by sound waves to digital audio signals.