METHODS AND APPARATUS FOR EMBEDDING WATERMARKS

• US 20100046795A1
• Filed: 11/05/2009
• Published: 02/25/2010
• Est. Priority Date: 06/13/2003
• Status: Active Grant

• Current Assignee: Nielsen Company (US) LLC (RR Donnelley & Sons Company)
• Original Assignee: Nielsen Company (US) LLC (RR Donnelley & Sons Company)
• Inventors: Srinivasan, Venugopal
• Granted Patent: US 8,085,975 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 25/27 characterised by the analysis technique

Abstract

Methods and apparatus for embedding a watermark are disclosed. An example method for embedding a watermark disclosed herein comprises identifying a transform coefficient associated with a compressed digital data stream, obtaining a mantissa code, and modifying the transform coefficient based on the mantissa code to embed the watermark.

Claims

1. A method for embedding a watermark comprising:

identifying a transform coefficient associated with a compressed digital data stream;

obtaining a mantissa code; and

modifying the transform coefficient based on the mantissa code to embed the watermark.

2. A method as defined in claim 1 wherein the mantissa code is a first mantissa code, and wherein modifying the transform coefficient comprises substituting the first mantissa code for a second mantissa code associated with the transform coefficient.

3. A method as defined in claim 1 wherein obtaining the mantissa code comprises:

selecting a code signal frequency to encode to the transform coefficient based on data to be embedded;

obtaining a masking energy associated with the code signal frequency to be encoded to the transform coefficient;

selecting a magnitude for a watermarked transform coefficient associated with the mantissa code based on the masking energy; and

determining the mantissa code based on the magnitude.

4. A method as defined in claim 3 wherein the code signal frequency comprises one or more sinusoidal components, and wherein each sinusoidal component includes a frequency based on a desired code.

5. A method as defined in claim 1 wherein modifying the transform coefficient comprises:

generating a time-domain audio block based on the transform coefficient;

generating a reconstructed audio block based on the time-domain audio block; and

generating a watermarked audio block based on the reconstructed audio block.

6. A method as defined in claims 1 wherein modifying the transform coefficient comprises generating a watermarked transform coefficient based on a first watermarked audio block and a second watermarked audio block.

7. A method as defined in claim 6 wherein generating the watermarked coefficient based on the first and second watermarked audio blocks comprises obtaining the mantissa code based on compression information associated with the compressed digital data stream.

8. A tangible article of manufacture storing machine readable instructions which, when executed, cause a machine to:

identify a transform coefficient associated with a compressed digital data stream;

obtain a mantissa code; and

modify the transform coefficient based on the mantissa code to embed a watermark.

9. A tangible article of manufacture as defined in claim 8 wherein the mantissa code is a first mantissa code, and wherein the machine readable instructions, when executed, further cause the machine to modify the transform coefficient by substituting the first mantissa code for a second mantissa code associated with the transform coefficient.

10. A tangible article of manufacture as defined in claim 8 wherein the machine readable instructions, when executed, further cause the machine to obtain the mantissa code by:

selecting a code signal frequency to encode to the transform coefficient based on data to be embedded;

obtaining a masking energy associated with the code signal frequency to be encoded to the transform coefficient;

selecting a magnitude for a watermarked transform coefficient associated with the mantissa code based on the masking energy; and

determining the mantissa code based on the magnitude.

11. A tangible article of manufacture as defined in claim 10 wherein the code signal frequency comprises one or more sinusoidal components, and wherein each sinusoidal component includes a frequency based on a desired code.

12. A tangible article of manufacture as defined in claim 8 wherein the machine readable instructions, when executed, further cause the machine to modify the transform coefficient by:

generating a time-domain audio block based on the transform coefficient;

generating a reconstructed audio block based on the time-domain audio block; and

generating a watermarked audio block based on the reconstructed audio block.

13. A tangible article of manufacture as defined in claim 8 wherein the machine readable instructions, when executed, further cause the machine to modify the transform coefficient by generating a watermarked transform coefficient based on a first watermarked audio block and a second watermarked audio block.

14. A tangible article of manufacture as defined in claim 13 wherein generating the watermarked coefficient based on the first and second watermarked audio blocks comprises obtaining the mantissa code based on compression information associated with the compressed digital data stream.

15. An apparatus for embedding a watermark comprising:

an identifier to identify a transform coefficient associated with a compressed digital data stream; and

a modifier to obtain a mantissa code and modify the transform coefficient based on the mantissa code to embed the watermark.

16. An apparatus as defined in claim 15 wherein the mantissa code is a first mantissa code, and wherein the modifier is to modify the transform coefficient by substituting the first mantissa code for a second mantissa code associated with the transform coefficient.

17. An apparatus as defined in claim 15 wherein the modifier is to obtain the mantissa code by:

selecting a code signal frequency to encode to the transform coefficient based on data to be embedded;

obtaining a masking energy associated with the code signal frequency to be encoded to the transform coefficient;

selecting a magnitude for a watermarked transform coefficient associated with the mantissa code based on the masking energy; and

determining the mantissa code based on the magnitude.

18. An apparatus as defined in claim 15 wherein the modifier is to modify the transform coefficient by:

generating a time-domain audio block based on the transform coefficient;

generating a reconstructed audio block based on the time-domain audio block; and

generating a watermarked audio block based on the reconstructed audio block.

19. An apparatus as defined in claim 15 wherein the modifier is to modify the transform coefficient by generating a watermarked transform coefficient based on a first watermarked audio block and a second watermarked audio block.

20. An apparatus as defined in claim 19 wherein generating the watermarked coefficient based on the first and second watermarked audio blocks comprises obtaining the mantissa code based on compression information associated with the compressed digital data stream.