Stealthy audio watermarking

• US 7,020,285 B1
• Filed: 07/12/2000
• Issued: 03/28/2006
• Est. Priority Date: 07/13/1999
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Kirovski, Darko, Malvar, Henrique
• Primary Examiner(s): REVAK, CHRISTOPHER A
• Application Number:
  US09/614,660
• Time in Patent Office: 2,085 Days
• Field of Search: 380200-203, 380/205, 380/210, 380/214, 380236-238, 380/243, 380/246, 380/252, 380/253, 382/232, 382/248, 382/250, 382/226, 382/280, 382/276, 713/176
• US Class Current: 380/238
• 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 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark

Abstract

Described herein is technology for inserting and detecting watermarks in signals, such as a music clip. In one described implementation, a watermarking system employs chess spread-spectrum sequences (i.e., “chess watermarks”) to improve the balance of positive and negative chips in the watermarking sequences. In another described implementation, a watermarking system employs an energy-level trigger to determine whether to skip encoding of a portion of a watermark within a given time span of a clip. If a large discrepancy in energy levels exists over a given time frame, then the frame is not watermarked, to avoid audible time-dispersion of artifacts due to spectral modifications. In another described implementation, a watermarking system begins encoding of a watermark at a variable position after the beginning of a clip.

Claims

1. A computer implemented method for concealing an information pattern of multiple discrete values within a digital signal, the method comprising:

receiving the information pattern of multiple discrete values;

absolute-chessboarding the discrete values of the information pattern to produce absolute-chessboarded discrete values, wherein absolute-chessboarding comprises adjusting successive discrete values of the information pattern so that the successive discrete values differ from immediately adjacent discrete values.

2. A method as recited in claim 1 further comprising encoding the chessboarded discrete values into the digital signal, wherein such signal is noise in relation to the information pattern.

3. A method as recited in claim 1, wherein;

each discrete value of the information pattern is represented by a defined set of multiple consecutive blocks, wherein in each consecutive block within a defined set includes its representative discrete value;

the absolute-chessboarding further comprises adjusting the information pattern of multiple discrete values so that the representative discrete values in the consecutive blocks of at least one defined set of the multiple discrete values differ from adjacent representative discrete values in the consecutive blocks of the same defined set.

4. A method as recited in claim 1, wherein the wherein:

each discrete value of the information pattern is represented by a defined set of multiple consecutive blocks, wherein each consecutive block within a defined set includes its representative discrete value and the consecutive blocks overlap with adjacent blocks in the time-domain;

the absolute-chessboarding further comprises adjusting the information pattern of multiple discrete values so that the representative discrete values in the consecutive blocks of at least one defined set of the multiple discrete values differ from adjacent representative discrete blocks of the same defined set.

5. A method as recited in claim 1, wherein the digital signal is a digital audio signal.

6. A computer-readable medium having computer-executable instructions that, when executed by a computer, performs the method as recited in claim 1.

7. A computer implemented method for revealing an information pattern of multiple absolute-chessboarded discrete values within a digital signal, wherein the absolute-chessboarded discrete values correspond to original discrete values of the information pattern before the values were absolute-chessboarded, the method comprising:

receiving the information pattern of multiple absolute-chessboarded discrete values;

un-chessboarding the absolute-chessboarded discrete values to produce the original values of the information pattern, wherein un-chessboarding comprises adjusting one or more discrete values of the information pattern.

8. A method as recited in claim 7 further comprising detecting the original discrete values encoded in the digital signal, wherein such signal is noise in relation to the information pattern.

9. A method as recited in claim 7, wherein the digital signal is of a digital audio signal.

10. A computer-readable medium having computer-executable instructions that, when executed by a computer, performs the method as recited in claim 7.

11. A computer-readable medium having computer-executable instructions that, when executed by a computer, perform a method for concealing an information pattern of multiple discrete values within a digital signal, the method comprising:

receiving the information pattern of multiple discrete values;

absolute-chessboarding the discrete values of the information pattern to produce absolute-chessboarded discrete values, wherein absolute-chessboarding comprises adjusting successive discrete values of the information pattern so that the successive discrete values differ from immediately adjacent discrete values;

encoding the absolute-chessboarded discrete values into the digital signal, wherein such signal is noise in relation to the information pattern.

12. A computer-readable medium having computer-executable instructions that, when executed by a computer, perform a method for revealing an information pattern of multiple absolute-chessboarded discrete values within a digital signal, wherein the absolute-chessboarded discrete values correspond to original discrete values of the information pattern before the values were absolute-chessboarded, the method comprising:

receiving the information pattern of multiple absolute-chessboarded discrete values;

un-chessboarding the absolute-chessboarded discrete values to produce the original values of the information pattern, wherein un-chessboarding comprises adjusting one or more discrete values of the information pattern;

detecting the original discrete values encoded in the digital signal, wherein such signal is noise in relation to the information pattern.

13. An apparatus comprising:

a processor;

an absolute-chessboarder executable on the processor to;

receive an information pattern of multiple discrete values;

absolute-chessboard the discrete values of the information pattern to produce absolute-chessboarded discrete values, wherein successive chessboarded discrete values differ from immediately adjacent discrete values.

14. An apparatus comprising:

a processor;

an un-chessboarder executable on the processor to;

receive an information pattern of multiple absolute-chessboarded discrete values;

un-chessboard the absolute-chessboarded discrete values to produce original values of the information pattern, wherein one or more of the un-chessboarded discrete values differs from the chessboarded discrete values before un-chessboarding.

15. An information pattern encoding system for concealing an information pattern of multiple discrete values within a digital signal, wherein such signal is noise in relation to the information pattern, the system comprising:

a receiver for receiving the information pattern of multiple discrete values and the digital signal;

an absolute-chessboarder coupled to such receiver, the chessboarder absolute-chessboards the values received from the receive to produce absolute-chessboarded discrete values, wherein successive chessboarded discrete values differ from immediately adjacent discrete values;

an encoder coupled to the receiver and the chessboarder, the encoder inserts the absolute-chessboarded discrete values received from the absolute-chessboarder into the digital signal received from the receiver.

16. An encoding system as recited in claim 15, wherein the digital signal is a digital audio signal.

17. An operating system comprising an encoding system as recited in claim 15.

18. A marked signal with an information pattern of multiple chessboarded discrete values encoded therein, the marked signal generated in accordance with the following acts:

receiving an information pattern of multiple discrete values and an unmarked signal;

absolute-chessboarding the discrete values of the information pattern to produce absolute-chessboarded discrete values, wherein absolute-chessboarding comprises adjusting successive discrete values of the information pattern so that the successive discrete values differ from immediately adjacent discrete values;

encoding the absolute-chessboarded discrete values into the unmarked signal to produce the marked signal, wherein such unmarked signal is noise in relation to the information pattern.

19. A marked signal as recited in claim 18, wherein the marked and unmarked signals are digital audio signals.

20. A computer implemented method for concealing an information pattern of multiple discrete values within a digital signal, the method comprising:

receiving the information pattern of multiple discrete values, wherein each discrete value of the information pattern is represented by a defined set of multiple consecutive blocks, wherein each consecutive block within a defined set includes its representative discrete value;

chessboard encoding the discrete values of the information pattern to produce chessboarded discrete values so that the representative discrete values in the consecutive blocks of at least one defined set of the multiple discrete values differ from adjacent representative discrete values in the consecutive blocks of the same defined set.

21. A method as recited in claim 20, wherein the chessboarded discrete values are absolutely chessboarded.

22. A method as recited in claim 20, wherein the digital signal is a digital audio signal.

23. One or more computer-readable media having computer-executable instructions that, when executed by a computer, performs the method as recited in claim 20.

24. A computer implemented method for concealing an information pattern of multiple discrete values within a digital signal, the method comprising:

receiving the information pattern of multiple discrete values, wherein each discrete value of the information pattern is represented by a defined set of multiple consecutive blocks, wherein each consecutive block within a defined set includes its representative discrete value;

generating a pseudorandom pattern based upon a pseudorandom number generator (PRNG) and a key;

chessboard encoding the discrete values of the information pattern to produce chessboarded discrete values, wherein chessboard encoding comprises adjusting the representative discrete values in the consecutive blocks of at least one defined set of the multiple discrete values in accordance with the pseudo-randomly generated pattern.

25. A method as recited in claim 24 further comprising encoding the chessboarded discrete values into the digital signal, wherein such signal is noise in relation to the information pattern.

26. A method as recited in claim 24, wherein The chessboarded discrete values are entropy-balanced.

27. A method as recited in claim 24, wherein the digital signal is a digital audio signal.

28. One or more computer-readable media having computer-executable instructions that, when executed by a computer, performs the method as recited in claim 24.