Steganographic encoding and decoding of auxiliary codes in media signals

• US 20060062386A1
• Filed: 09/13/2005
• Published: 03/23/2006
• Est. Priority Date: 11/18/1993
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Granted Patent: US 8,204,222 B2
• Time in Patent Office: Days
• US Class Current: 380/236
• 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 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• 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 17/16 for devices exhibiting advertisements, announcements, pictures or the like
• 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: 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 20/00166 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 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• 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 1/32122 : in a separate device, e.g. in a memory or on a display separate from image data
• 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 1/32208 : 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 1/32251 : 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 2201/3226 : 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 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3271 : Printing or stamping
• CPC Class Codes: H04N 2201/328 : Processing of the additional information
• CPC Class Codes: H04N 5/913 : for scrambling ; for copy protection

Abstract

One aspect of the invention is a method of decoding an auxiliary code embedded in an audio signal. The method performs a statistical decoding of a multibit auxiliary code embedded in an audio signal. The auxiliary code has been repetitively embedded in the audio signal. The method decodes code values of the auxiliary code from two or more different portions of the audio signal, each having the multibit auxiliary code. It then uses the code values decoded from two or more different portions to determine statistically the code values of the auxiliary code. Another aspect of the invention is another method of decoding an auxiliary code embedded in an audio signal. The method receives an audio signal suspected of being embedded with an auxiliary code. It evaluates a statistical feature of a portion of the audio signal to decode code values of the auxiliary code from the audio signal. It then determines a code value in the auxiliary code based on the statistical feature. The statistical feature may comprise, for example, the power of the audio signal. The statistical feature may be analyzed over different portions of the audio signal to decode two or more values of the auxiliary code.

Claims

1. A method of decoding an auxiliary code embedded in an audio signal, the method comprising:

performing decoding of a multibit auxiliary code embedded in an audio signal, where the auxiliary code has been repetitively embedded in the audio signal;

decoding code values of the auxiliary code from two or more different portions of the audio signal, each having the multibit auxiliary code;

using the code values decoded from the two or more different portions of the audio signal to determine the code values of the auxiliary code;

wherein pseudo random data is used to detect the auxiliary code and a carrier of the auxiliary code is varied over time to vary representation of the auxiliary code in the audio over time.

2. A method of decoding an auxiliary code embedded in an audio signal, the method comprising:

receiving an audio signal suspected of being embedded with an auxiliary code;

evaluating a feature of a portion of the audio signal to decode code a value of the auxiliary code from the audio signal, the auxiliary code being conveyed using a carrier that varies over time; and

determining a code value in the auxiliary code based on the feature.

3. The method of claim 2 wherein the feature is analyzed over different portions of the audio signal to decode two or more values of the auxiliary code.

4. The method of claim 3 wherein each of the two or more code values are decoded from corresponding time domain portion of the audio signal, and the feature for each code value is evaluated over the corresponding time domain portion.

5. The method of claim 2 wherein the auxiliary code signal is repeated in different time domain portions of the audio signal.

6. The method of claim 5 wherein results of analyzing the feature over the time domain portions in which the auxiliary code signal is repeated are used to recover the auxiliary code.

7. The method of claim 2 wherein the auxiliary code comprises a code that enables or disables recording capabilities.

8. The method of claim 2 wherein the auxiliary code comprises an identification code.

9. The method of claim 2 wherein the auxiliary code comprises a code used to monitor a broadcast of the audio signal.

10. The method of claim 2 wherein the auxiliary code comprises a code that triggers transmission of information about the audio signal from a decoding device to a service provider.

11. The method of claim 2 wherein the auxiliary code is used to generate a report about use of the audio signal.

12. A method of steganographically encoding auxiliary data into audio, the method comprising:

mapping the auxiliary data to samples in the audio data;

modifying the mapping of the auxiliary data to the samples over time; and

modifying a feature of the audio data to convey the auxiliary data substantially imperceptibly in the audio data.

13. The method of claim 12 wherein the audio with encoded auxiliary data is a non linear function of the audio in which the auxiliary data is encoded.

14. The method of claim 12 wherein pseudorandom data is used to convey the auxiliary data in the audio so that the auxiliary data is robust to errors.

15. The method of claim 12 wherein the auxiliary data comprises a binary code, and elements of the binary code are redundantly encoded in the audio such that the binary code is decodable from portions of the audio.

16. The method of claim 15 wherein elements of the binary code are spread over non overlapping portions of the audio.

17. The method of claim 16 wherein the binary code is recoverable from non-overlapping portions of the audio.

18. The method of claim 17 wherein instances of the auxiliary data are repeated in the audio such that there is border continuity among the instances of the auxiliary data.

19. The method of claim 17 including concentrating the auxiliary data at a frequency range so that the auxiliary data in the audio is likely to survive losses due to compression of the audio.

20. The method of claim 19 wherein concentrating the auxiliary data includes selected a desired frequency.