Methods and apparatus to perform audio watermarking and watermark detection and extraction
Encoding and decoding methods and apparatus are described. An example method is described for embedding information into audio by determining a first set of frequency components to represent a synchronization block, the synchronization block representing one of a plurality of different message types, one frequency component from each set of frequency components being located in a respective code band, 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 respective ones of the first set of frequency components representing the synchronization block based on a masking ability of an audio block of the audio. Synthesizing the first set of frequency components representing the synchronization block to determine a first set of synthesized code frequency components, based on the determined amplitudes. Combining the first set of synthesized code frequency components with the audio block.
1. A method of embedding information into audio, the method comprising:
determining, by executing an instruction with a processor, a first set of frequency components to represent a synchronization block, the synchronization block representing one of a plurality of different message types, different sets of frequency components representing respectively different information, one frequency component from each set of frequency components being located in a respective code band, there are multiple code bands, and spacing between adjacent code bands is equal to or less than spacing between adjacent frequency components of each code band;
determining, by executing an instruction with the processor, amplitudes of respective ones of the first set of frequency components representing the synchronization block, the amplitudes being determined by a masking ability of an audio block of the audio;
synthesizing, by executing an instruction with the processor, the respective ones of the first set of frequency components representing the synchronization block to determine a first set of synthesized code frequency components, the first set of synthesized code frequency components being synthesized with the determined amplitudes; and
combining, by executing an instruction with the processor, the first set of synthesized code frequency components with the audio block.
2. The method as defined in claim 1 , wherein there are sixteen different message types.
3. The method as defined in claim 2 , where a first frequency range including first code frequencies representing each of the sixteen different message types is larger than a frequency amount separating the first frequency range from an adjacent second frequency range including second code frequencies also representing each of the sixteen different message types.
4. The method as defined in claim 1 , further including:
determining a second set of frequency components to represent a data payload of the message specified by the synchronization block;
determining amplitudes of respective ones of the second set of frequency components representing the data payload, the amplitudes of the respective ones of the second set of frequency components being determined by the masking ability of the audio block;
synthesizing the respective ones of the second set of frequency components representing the data payload to determine a second set of synthesized code frequency components, the second set of synthesized code frequency components are synthesized with the determined amplitudes; and
combining the second set of synthesized code frequency components with the audio block.
5. The method as defined in claim 4 , wherein the data payload includes at least one data block following the synchronization block.
6. The method as defined in claim 1 , wherein the respective ones of the first set of frequency components are in an audible frequency range.
7. The method as defined in claim 1 , wherein the multiple code bands include seven code bands.
8. The method as defined in claim 7 , wherein the spacing between adjacent frequency components within a code band correspond to a spacing of one frequency index, the spacing between adjacent code bands correspond to the spacing of one frequency index and the different sets of frequency components include 144 different sets of frequency components and each code band includes 144 different frequency indices.
9. An apparatus to embed auxiliary information into an audio signal, the apparatus comprising:
a code frequency selector to receive a message type and to determine a first set of frequency components to represent a synchronization block, the synchronization block representing one of a plurality of different message types, different sets of frequency components representing respectively different information, one frequency component from each set of frequency components being located in a respective code band, there are multiple code bands, and spacing between adjacent code bands is equal to or less than spacing between adjacent frequency components of each code band;
a masking evaluator to determine amplitudes of respective ones of the first set of frequency components representing the synchronization block, the amplitudes being determined by a masking ability of an audio block of the audio;
a code synthesizer to synthesize the respective ones of the first set of the frequency components representing the synchronization block to determine a first set of synthesized code frequency components, wherein the first set of synthesized code frequency components being synthesized with the determined amplitudes; and
a combiner to combine the first set of synthesized code frequency components with the audio block.
10. The apparatus as defined in claim 9 , wherein there are sixteen different message types.
11. The apparatus as defined in claim 10 , where a first frequency range including first code frequencies representing each of the sixteen different message types is larger than a frequency amount separating the first frequency range from an adjacent second frequency range including second code frequencies also representing each of the sixteen different message types.
12. The apparatus as defined in claim 9 , further including:
the code frequency selector to determine a second set of frequency components to represent a data payload of the message specified by the synchronization block;
the masking evaluator to determine amplitudes of respective ones of the second set of frequency components representing the data payload, the amplitudes of the respective ones of the second set of frequency components being determined by the masking ability of the audio block;
the code synthesizer to synthesize the respective ones of the second set of frequency components representing the data payload to determine a second set of synthesized code frequency components, the second set of synthesized code frequency components being synthesized with the determined amplitudes; and
the combiner to combine the second set of synthesized code frequency components with the audio block.
13. The apparatus as defined in claim 12 , wherein the data payload includes at least one data block following the synchronization block.
14. The apparatus as defined in claim 9 , wherein the respective ones of the first set of frequency components are in an audible frequency range.
15. The apparatus as defined in claim 9 , wherein the multiple code bands include seven code bands.
16. The apparatus as defined in claim 15 , wherein the spacing between adjacent frequency components within a code band correspond to a spacing of one frequency index, the spacing between adjacent code bands correspond to the spacing of one frequency index and the different sets of frequency components include 144 different sets of frequency components and each code band includes 144 different frequency indices.
17. An article of manufacture comprising computer readable instructions which, when executed, cause a computer to:
determine a first set of frequency components to represent a synchronization block, the synchronization block representing one of a plurality of different message types, different sets of frequency components representing respectively different information, one frequency component from each set of frequency components being located in a respective code band, there are multiple code bands, and spacing between adjacent code bands is equal to or less than spacing between adjacent frequency components of each code band;
determine amplitudes of respective ones of the first set of frequency components representing the synchronization block, the amplitudes being determined by a masking ability of an audio block;
synthesize the respective ones of the first set of frequency components representing the synchronization block to determine a first set of synthesized code frequency components, wherein the first set of synthesized code frequency components being synthesized with the determined amplitudes; and
combine the first set of synthesized code frequency components with the audio block.
18. The article of manufacture as defined in claim 17 , wherein there are sixteen different message types.
19. The article of manufacture as defined in claim 18 , where a first frequency range including first code frequencies representing each of the sixteen different message types is larger than a frequency amount separating the first frequency range from an adjacent second frequency range including second code frequencies also representing each of the sixteen different message types.
20. The article of manufacture as defined in claim 17 , wherein the instructions, when executed, further cause the computer to:
determine a second set of frequency components to represent a data payload of the message specified by the synchronization block;
determine amplitudes of respective ones of the second set of frequency components representing the data payload, the amplitudes of respective ones of the second set of frequency components being determined by the masking ability of the audio block;
synthesize the respective ones of the second set of frequency components representing the data payloads to determine a second set of synthesized code frequency components, the second set of synthesized code frequency components being synthesized with the determined amplitudes; and
combine the second set of synthesized code frequency components with the audio block.
21. The article of manufacture as defined in claim 20 , wherein the data payload includes at least one data block following the synchronization block.
22. The article of manufacture as defined in claim 17 , wherein the respective ones of the first set of frequency components are in an audible frequency range.
23. The article of manufacture as defined in claim 17 , wherein the multiple code bands include seven code bands.
24. The article of manufacture as defined in claim 17 , wherein the spacing between adjacent frequency components within a code band correspond to a spacing of one frequency index, the spacing between adjacent code bands correspond to the spacing of one frequency index and the different sets of frequency components include 144 different sets of frequency components and each code band includes 144 different frequency indices.