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

• US 20100223062A1
• Filed: 05/12/2009
• Published: 09/02/2010
• Est. Priority Date: 10/24/2008
• 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, Topchy, Alexander Pavlovich
• Granted Patent: US 9,667,365 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G10L 19/0208 Subband vocoders
• CPC Class Codes: G10L 19/173 Transcoding, i.e. converting between two coded representations avoiding cascaded coding-decoding
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04H 60/37 for identifying segments of broadcast information, e.g. scenes or extracting programme ID
• CPC Class Codes: H04H 60/58 of audio determination or detection of speech characteristics in general G10L25/00; speech recognition in general G10L15/00

Abstract

Methods and apparatus to audio watermarking and watermark detection and extracted are described herein. According to an example method, an identifier is encoded in media content when a different identifier has been previously encoded. According to another example method, messages decoded from media content are validated to provide improved decoding accuracy. In another example method, decoded symbols are stored in memory and synchronization symbols are located to detect a message encoded in media content.

Claims

1. A method to transform media content to include an encoding, the method comprising:

receiving audio samples to be encoded;

detecting a first encoded identification code in the audio samples;

in response to the detection, encoding a pre-existing code flag in the audio samples and encoding a second identification code in the audio samples to transform the audio samples into encoded audio samples; and

storing the encoded audio samples in a tangible memory.

2. A method as defined in claim 1, wherein a first identification symbol look-up table is used when encoding the first encoded identification code, the second identification being encoded using a second identification symbol look-up table different from the first identification symbol look-up table.

3. A method as defined in claim 1, wherein the first encoded identification code comprises a first encoding at a first time and a second encoding at a second time and encoding the second identification comprises encoding the second identification between the first encoding and the second encoding.

4. A method as defined in claim 3, wherein encoding the pre-existing code flag comprises encoding the pre-existing code flag between the first encoding and the second encoding.

5. A method as defined in claim 1, wherein encoding the second identification code comprises:

identifying a set of frequencies corresponding to the second identification code; and

emphasizing the frequencies in the set of frequencies.

6. A method as defined in claim 5, wherein emphasizing the frequencies comprises:

generating at least one code signal having at least one frequency from the set of frequencies amplified; and

adding the at least one code signal to the audio samples.

7. A method as defined in claim 1, wherein the first encoded identification identifies a first media content distributor that broadcast media content of the audio samples at a first time and the second identification code identifies a second media content distributor that broadcast the media content at a second time later than the first time.

8. An apparatus to transform media content to include an encoding, the apparatus comprising:

a prior code detector to receive audio samples to be encoded and to detect a first encoded identification code in the audio samples;

a code frequency selector to identify a set of frequencies corresponding to a second identification code;

a code signal synthesizer to, in response to the detection, generate at least one code signal having at least one frequency from the set of frequencies to be amplified; and

a mixer to combine the at least one code signal and the audio samples to encode a pre-existing code flag in the audio samples and encode a second identification code in the audio samples to transform the audio samples into encoded audio samples and to store the encoded audio samples in a tangible memory.

9. An apparatus as defined in claim 8, wherein a first identification symbol look-up table is used when encoding the first encoded identification code and the code frequency selector uses a second identification symbol look-up table to identify the set of frequencies corresponding to the second identification code.

10. An apparatus as defined in claim 8, wherein the first encoded identification code comprises a first encoding at a first time and a second encoding at a second time and encoding the second identification comprises encoding the second identification between the first encoding and the second encoding.

11. An apparatus as defined in claim 10, wherein encoding the pre-existing code flag comprises encoding the pre-existing code flag between the first encoding and the second encoding.

12. A method as defined in claim 8, wherein the first encoded identification identifies a first media content distributor that broadcast media content of the audio samples at a first time and the second identification code identifies a second media content distributor that broadcast the media content at a second time later than the first time.

13. A tangible computer readable medium storing instructions that when executed cause a machine to transform media content to include an encoding by:

receiving audio samples to be encoded;

detecting a first encoded identification code in the audio samples;

in response to the detection, encoding a pre-existing code flag in the audio samples and encoding a second identification code in the audio samples to transform the audio samples into encoded audio samples; and

storing the encoded audio samples in a tangible memory.

14. A tangible computer readable medium as defined in claim 13, wherein a first identification symbol look-up table is used when encoding the first encoded identification code, the second identification being encoded using a second identification symbol look-up table different from the first identification symbol look-up table.

15. A tangible computer readable medium as defined in claim 13, wherein the first encoded identification code comprises a first encoding at a first time and a second encoding at a second time and encoding the second identification comprises encoding the second identification between the first encoding and the second encoding.

16. A tangible computer readable medium as defined in claim 15, wherein encoding the pre-existing code flag comprises encoding the pre-existing code flag between the first encoding and the second encoding.

17. A tangible computer readable medium as defined in claim 13, wherein encoding the second identification code comprises:

identifying a set of frequencies corresponding to the second identification code; and

emphasizing the frequencies in the set of frequencies.

18. A tangible computer readable medium as defined in claim 17, wherein emphasizing the frequencies comprises:

generating at least one code signal having at least one frequency from the set of frequencies amplified; and

adding the at least one code signal to the audio samples.

19. A tangible computer readable medium as defined in claim 13, wherein the first encoded identification identifies a first media content distributor that broadcast media content of the audio samples at a first time and the second identification code identifies a second media content distributor that broadcast the media content at a second time later than the first time.

20. A method to transform media content into a message, the method comprising:

receiving encoded audio samples;

determining a first symbol encoded in the encoded audio samples;

storing the first symbol in a tangible memory;

determining a second symbol encoded in the encoded audio samples;

storing the second symbol in the tangible memory;

determining that the first symbol matches the second symbol; and

in response to the determination;

determining that the first symbol and the second symbol are validated, and

outputting the first symbol.

21. A method as defined in claim 20, wherein the first symbol and the second symbol are stored in a stack in the tangible memory.

22. A method as defined in claim 21, further comprising popping the first symbol from the stack in response to the determination.

23-34. -34. (canceled)

35. A method to transform media content into a message, the method comprising:

receiving encoded audio samples;

detecting sequentially in the encoded audio samples a first symbol, a second symbol, a third symbol, and a fourth symbol;

storing the first symbol, the second symbol, the third symbol, and the fourth symbol in a tangible memory;

determining that the first symbol is a synchronization symbol;

in response to the determination, determining that the first symbol and the third symbol as associated with a first message and the second symbol and the fourth symbol are associated with a second message; and

outputting the first message.

36. A method as defined in claim 35, further comprising storing the first message in the tangible memory.

37. A method as defined in claim 35, wherein first symbol, the second symbol, the third symbol, and the fourth symbol are stored in at least one circular buffers in the tangible memory.

38-62. -62. (canceled)