Methods for audio watermarking and decoding

• US 20060109984A1
• Filed: 01/03/2006
• Published: 05/25/2006
• Est. Priority Date: 11/18/1993
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Granted Patent: US 7,536,555 B2
• Time in Patent Office: Days
• US Class Current: 380/252
• 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

An identification code signal is hidden in a carrier signal (such as an electronic data signal or a physical medium) in a manner that permits the identification signal later to be discerned. The carrier signal can thereby be identified, or some machine responsive action can thereby be taken. The technique can be applied in audio and video embodiments to control associated consumer electronic equipment, e.g. to serve as a copy control signal.

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 method comprising:

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, 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.

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. The method of claim 1 wherein the audio signal has been compressed using a lossy compression method, yet the auxiliary data is decodable from the audio signal despite changes to the audio signal due to the lossy compression.

8. A machine readable medium on which is stored instructions for performing the method of claim 1.

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

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.

10. The method of claim 9 including providing calibration data in the embedded signal to facilitate decoding of the auxiliary code from the altered signal.

11. The method of claim 10 wherein the calibration data comprises a pseudorandom signal.

12. The method of claim 9 including embedding the auxiliary code in the audio signal such that the auxiliary code can be recovered from the altered audio signal despite lossy compression of the altered audio signal.

13. The method of claim 9 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 method of decoding an auxiliary code from a digital audio signal wherein the digital audio signal has been altered in accordance with an embedded signal so as to encode an auxiliary code therein, reference data and the auxiliary code having been used to generate the embedded signal, the association between the embedded signal and the auxiliary code being indiscernible without availability of the reference data, wherein the embedded signal has been generated by using reference data to convey the auxiliary code, and features of the auxiliary data have been adjusted according to the reference data such that the encoding of the auxiliary code in the digital audio signal preserves aural information of the digital audio signal without human perceptible degradation, the method comprising:

detecting the embedded code signal; and

ascertaining values of the auxiliary code through a process that includes using repeated auxiliary data extracted from successive blocks of the audio data to improve statistical confidence of accurate recovery of the auxiliary code.

15. The method of claim 14 including using reference data to calibrate detection of the auxiliary data.

16. The method of claim 15 wherein the reference data comprises a predetermined pseudorandom sequence.

17. The method of claim 14 wherein features of blocks in the audio data are modified to convey the auxiliary data.

18. The method of claim 17 wherein the features comprise signal power values calculated from the blocks.

19. The method of claim 14 wherein reference data comprises pseudo random carrier data used to convey variable multi-bit message data.

20. The method of claim 19 wherein the pseudorandom carrier data is previously used to modify features of the blocks to embed the auxiliary data in the blocks.

21. The method of claim 14 wherein the audio signal has been compressed using a lossy compression method, yet the auxiliary data is decodable from the audio signal despite changes to the audio signal due to the lossy compression.

22. A method comprising:

receiving a representation of audio in compressed form;

processing said compressed form to discern a steganographically encoded plural-bit auxiliary code therefrom;

wherein encoding of the auxiliary code in the compressed form was adapted to survive a lossy compression-decompression operation that thereby distorts the decompressed form of the audio as compared with the audio prior to compression.

23. The method of claim 22 which includes limiting ability of an apparatus to record the audio based on the discerned auxiliary code.