METHODS AND APPARATUS TO PERFORM AUDIO WATERMARKING AND WATERMARK DETECTION AND EXTRACTION

• US 20090259325A1
• Filed: 10/10/2008
• Published: 10/15/2009
• Est. Priority Date: 11/12/2007
• Status: Active Grant

• Current Assignee: Nielsen Company (US) LLC (RR Donnelley & Sons Company)
• Original Assignee: Nielsen Company (US) LLC (RR Donnelley & Sons Company)
• Inventors: Ramaswamy, Arun, Srinivasan, Venugopal, Topchy, Alexander Pavlovich
• Granted Patent: US 8,369,972 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• 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: G10L 19/06 Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients
• CPC Class Codes: G10L 25/18 the extracted parameters being spectral information of each sub-band
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04H 2201/50 characterised by the use of watermarks
• CPC Class Codes: H04H 60/31 Arrangements for monitoring the use made of the broadcast services
• CPC Class Codes: H04N 19/467 characterised by the embedded information being invisible, e.g. watermarking
• CPC Class Codes: H04N 21/23892 involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467

Abstract

Encoding and decoding methods and apparatus as described. In one example, a method of embedding auxiliary information into an audio signal includes sampling the audio signal to create an audio block; receiving a code; determining frequency components that will be used to represent the code, wherein different sets of frequency components represent respectively different information and wherein one frequency component from each set of frequency components is located in a code band and there are multiple code bands and spacing between adjacent code bands is equal to or less than the spacing between adjacent frequency components of each code band; determining amplitudes of the frequency components that will be used to represent the information, wherein the amplitudes of the frequency components are determined by a masking ability of the audio block; synthesizing the frequency components that will be used to represent the information, wherein the frequency components are synthesized with the determined amplitudes; and combining the synthesized code frequency components with the audio block.

Claims

1. A method of embedding auxiliary information into an audio signal, the method comprising:

sampling the audio signal to create an audio block;

receiving a code;

determining frequency components that will be used to represent the code, wherein different sets of frequency components represent respectively different information and wherein one frequency component from each set of frequency components is located in a code band and there are multiple code bands and spacing between adjacent code bands is equal to or less than the spacing between adjacent frequency components of each code band;

determining amplitudes of the frequency components that will be used to represent the information, wherein the amplitudes of the frequency components are determined by a masking ability of the audio block;

synthesizing the frequency components that will be used to represent the information, wherein the frequency components are synthesized with the determined amplitudes; and

combining the synthesized code frequency components with the audio block.

2. A method as defined in claim 1, wherein the frequency components used to represent the information are in an audible frequency range.

3. A method as defined in claim 1, wherein the multiple code bands comprise seven code bands.

4. A method as defined in claim 3, wherein the spacing between adjacent frequency components within a code band comprises one frequency index.

5. A method as defined in claim 4, wherein the spacing between adjacent code bands comprises one frequency index.

6. A method as defined in claim 5, wherein the different sets of frequency components comprise 144 different sets of frequency components.

7. A method as defined in claim 6, wherein each code band comprises 144 different frequency indices.

8. A method as defined in claim 7, wherein at least one of the sets of frequency components represents a synchronization symbol.

9. A method as defined in claim 8, wherein the synchronization symbol indicates a characteristic of information following the synchronization symbol.

10. A method as defined in claim 7, wherein a single set of frequency components is selected for inclusion in the audio block at one particular time.

11. A method as defined in claim 10, wherein the single set of frequency components is included in multiple successive audio blocks.

12. A method of obtaining auxiliary information previously embedded into an audio signal using a plurality of frequency components residing in a plurality of code bands, the method comprising:

sampling an audio signal;

transforming the audio signal into a frequency domain representation;

determining a characteristic of each frequency of the frequency domain representation that may contain the auxiliary information;

normalizing across each code band the characteristic of each frequency of the frequency domain representation in that code band that may contain the auxiliary information, wherein the normalization is carried out against a maximum characteristic of a frequency in that code band;

summing the normalized characteristics of each frequency representative of auxiliary information to determine a maximum sum for a frequency representative of auxiliary information;

determining that the maximum sum is representative of the auxiliary information.

13. A method as defined by claim 12, wherein different sets of frequency components represent respectively different information and wherein one frequency component from each set of frequency components is located in a code band and there are multiple code bands and spacing between adjacent code bands is equal to or less than the spacing between adjacent frequency components of each code band.

14. A method as defined by claim 13, wherein the characteristic of each frequency that may contain the auxiliary information is the amplitude of the frequency.

15. A method as defined by claim 13, wherein the characteristic of each frequency that may contain the auxiliary information is the energy of the frequency.

16. A method as defined by claim 12, further comprising reducing the number of frequencies processed after a first portion of auxiliary information is determined.

17. A method as defined by claim 16, wherein the first portion of auxiliary information comprises synchronization information.

18. An apparatus to embed auxiliary information into an audio signal, the apparatus comprising:

a sampler to sample the audio signal to create an audio block;

a code frequency selector to receive a code and to determine frequency components that will be used to represent the code, wherein different sets of frequency components represent respectively different information and wherein one frequency component from each set of frequency components is located in a code band and there are multiple code bands and spacing between adjacent code bands is equal to or less than the spacing between adjacent frequency components of each code band;

a masking evaluator to determine amplitudes of the frequency components that will be used to represent the information, wherein the amplitudes of the frequency components are determined by a masking ability of the audio block;

a code synthesizer to synthesize the frequency components that will be used to represent the information, wherein the frequency components are synthesized with the determined amplitudes; and

a combiner to combine the synthesized code frequency components with the audio block.

19. An apparatus as defined in claim 18, wherein the frequency components used to represent the information are in an audible frequency range.

20. An apparatus as defined in claim 18, wherein the multiple code bands comprise seven code bands.

21. An apparatus as defined in claim 20, wherein the spacing between adjacent frequency components within a code band comprises one frequency index.

22. An apparatus as defined in claim 21, wherein the spacing between adjacent code bands comprises one frequency index.

23. An apparatus as defined in claim 22, wherein the different sets of frequency components comprise 144 different sets of frequency components.

24. An apparatus as defined in claim 23, wherein each code band comprises 144 different frequency indices.

25. An apparatus as defined in claim 24, wherein at least one of the sets of frequency components represents a synchronization symbol.

26. An apparatus as defined in claim 25, wherein the synchronization symbol indicates a characteristic of information following the synchronization symbol.

27. An apparatus as defined in claim 24, wherein a single set of frequency components is selected for inclusion in the audio block at one particular time.

28. An apparatus as defined in claim 27, wherein the single set of frequency components is included in multiple successive audio blocks.

29. An apparatus to obtain auxiliary information previously embedded into an audio signal using a plurality of frequency components residing in a plurality of code bands, the apparatus comprising:

a sampler to sample an audio signal;

a time-to-frequency domain converter to transform the audio signal into a frequency domain representation;

a code frequency monitor to determine a characteristic of each frequency of the frequency domain representation that may contain the auxiliary information and to normalize across each code band the characteristic of each frequency of the frequency domain representation in that code band that may contain the auxiliary information, wherein the normalization is carried out against a maximum characteristic of a frequency in that code band and to sum the normalized characteristics of each frequency representative of auxiliary information to determine a maximum sum for a frequency representative of auxiliary information and to determine that the maximum sum is representative of the auxiliary information.

30. An apparatus as defined by claim 29, wherein different sets of frequency components represent respectively different information and wherein one frequency component from each set of frequency components is located in a code band and there are multiple code bands and spacing between adjacent code bands is equal to or less than the spacing between adjacent frequency components of each code band.

31. An apparatus as defined by claim 30, wherein the characteristic of each frequency that may contain the auxiliary information is the amplitude of the frequency.

32. An apparatus as defined by claim 30, wherein the characteristic of each frequency that may contain the auxiliary information is the energy of the frequency.

33. An apparatus as defined by claim 30, further comprising reducing the number of frequencies processed after a first portion of auxiliary information is determined.

34. An apparatus as defined by claim 33, wherein the first portion of auxiliary information comprises synchronization information.

35-51. -51. (canceled)