Methods and apparatus for embedding watermarks
View Patent ↗Methods and apparatus for embedding a watermark are disclosed. Example methods disclosed herein to embed a watermark in a compressed data stream include obtaining a set of transform coefficients from the compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a first set of exponents. Disclosed example methods also include determining a second set of mantissa codes based on a sinusoidal component of the watermark. Disclosed example methods further include adjusting ones of the first set of mantissa codes based on corresponding ones of the second set of mantissa codes and compression information obtained from the compressed data stream to embed the watermark in the compressed data stream without uncompressing the compressed data stream.
1. A method to embed a watermark in a compressed data stream, the method comprising:
obtaining a set of transform coefficients from the compressed data stream, the set of transform coefficients including a first set of mantissa codes and a first set of exponents;
determining a second set of mantissa codes based on a sinusoidal component of the watermark; and
adjusting ones of the first set of mantissa codes based on corresponding ones of the second set of mantissa codes and compression information obtained from the compressed data stream to embed the watermark in the compressed data stream without uncompressing the compressed data stream.
2. A method as defined in claim 1 , further comprising:
synthesizing a first audio block of audio samples to correspond to a first portion of the sinusoidal component of the watermark having a first amplitude;
synthesizing a second audio block of audio samples to correspond to a second portion of the sinusoidal component of the watermark having a second amplitude different from the first amplitude; and
determining the second set of mantissa codes from at least one of the first audio block or the second audio block.
3. A method as defined in claim 1 , wherein adjusting the ones of the first set of mantissa codes includes:
normalizing a first one of the second set of mantissa codes based on a second one of the second set of mantissa codes; and
adjusting a first one of the first set of mantissa codes corresponding to the first one of the second set of mantissa codes based on the normalized first one of the second set of mantissa codes.
4. A method as defined in claim 3 , further comprising adjusting a second one of the first set of mantissa codes corresponding to the second one of the second set of mantissa codes by a value of one.
5. A method as defined in claim 1 , wherein the watermark includes a plurality of sinusoidal components, and determining the second set of mantissa codes includes determining the second set of mantissa codes based on the plurality of sinusoidal components of the watermark.
6. A method as defined in claim 1 , wherein the compression information specifies a mantissa step size, and adjusting the ones of the first set of mantissa codes includes adjusting the ones of the first set of mantissa codes based on the corresponding ones of the second set of mantissa codes and the mantissa step size.
7. A method as defined in claim 1 , wherein the first set of exponents is unchanged in the compressed data stream after the watermark is embedded.
8. A tangible computer readable storage device or storage disk comprising computer readable instructions which, when executed, cause a computing device to at least:
obtain a set of transform coefficients from a compressed data stream, the set of transform coefficients including a first set of mantissa codes and a first set of exponents;
determine a second set of mantissa codes based on a sinusoidal component of a watermark; and
adjust ones of the first set of mantissa codes based on corresponding ones of the second set of mantissa codes and compression information obtained from the compressed data stream to embed the watermark in the compressed data stream without uncompressing the compressed data stream.
9. A storage device or storage disk as defined in claim 8 , wherein the instructions, when executed, further cause the computing device to:
synthesize a first audio block of audio samples to correspond to a first portion of the sinusoidal component of the watermark having a first amplitude;
synthesize a second audio block of audio samples to correspond to a second portion of the sinusoidal component of the watermark having a second amplitude different from the first amplitude; and
determine the second set of mantissa codes from at least one of the first audio block or the second audio block.
10. A storage device or storage disk as defined in claim 8 , wherein the instructions, when executed, further cause the computing device to adjust the ones of the first set of mantissa codes by:
normalizing a first one of the second set of mantissa codes based on a second one of the second set of mantissa codes; and
adjusting a first one of the first set of mantissa codes corresponding to the first one of the second set of mantissa codes based on the normalized first one of the second set of mantissa codes.
11. A storage device or storage disk as defined in claim 10 , wherein the instructions, when executed, further cause the computing device to adjust a second one of the first set of mantissa codes corresponding to the second one of the second set of mantissa codes by a value of one.
12. A storage device or storage disk as defined in claim 8 , wherein the watermark includes a plurality of sinusoidal components, and the instructions, when executed, further cause the computing device to determine the second set of mantissa codes based on the plurality of sinusoidal components of the watermark.
13. A storage device or storage disk as defined in claim 8 , wherein the compression information specifies a mantissa step size, and the instructions, when executed, further cause the computing device to adjust the ones of the first set of mantissa codes based on the corresponding ones of the second set of mantissa codes and the mantissa step size.
14. A storage device or storage disk as defined in claim 8 , wherein the first set of exponents is unchanged in the compressed data stream after the watermark is embedded.
15. An apparatus to embed a watermark in a compressed data stream, the apparatus comprising:
an unpacking unit to obtain a set of transform coefficients from a compressed data stream, the set of transform coefficients including a first set of mantissa codes and a first set of exponents; and
a modification unit to:
determine a second set of mantissa codes based on a sinusoidal component of a watermark; and
adjust ones of the first set of mantissa codes based on corresponding ones of the second set of mantissa codes and compression information obtained from the compressed data stream to embed the watermark in the compressed data stream without uncompressing the compressed data stream.
16. An apparatus as defined in claim 15 , wherein the modification unit is further to:
synthesize a first audio block of audio samples to correspond to a first portion of the sinusoidal component of the watermark having a first amplitude;
synthesize a second audio block of audio samples to correspond to a second portion of the sinusoidal component of the watermark having a second amplitude different from the first amplitude; and
determine the second set of mantissa codes from at least one of the first audio block or the second audio block.
17. An apparatus as defined in claim 15 , wherein modification unit is to adjust the ones of the first set of mantissa codes by:
normalizing a first one of the second set of mantissa codes based on a second one of the second set of mantissa codes; and
adjusting a first one of the first set of mantissa codes corresponding to the first one of the second set of mantissa codes based on the normalized first one of the second set of mantissa codes.
18. An apparatus as defined in claim 17 , wherein modification unit is to adjust a second one of the first set of mantissa codes corresponding to the second one of the second set of mantissa codes by a value of one.
19. An apparatus as defined in claim 15 , wherein the watermark includes a plurality of sinusoidal components, and the modification unit is to determine the second set of mantissa codes based on the plurality of sinusoidal components of the watermark.
20. An apparatus as defined in claim 15 , wherein the compression information specifies a mantissa step size, and the modification unit is to adjust the ones of the first set of mantissa codes based on the corresponding ones of the second set of mantissa codes and the mantissa step size.
21. An apparatus as defined in claim 15 , wherein the first set of exponents is unchanged in the compressed data stream after the watermark is embedded.