Methods for encoding, decoding and interpreting auxiliary data in media signals
The disclosure relates to digital watermarking, steganography, and specifically to message coding protocols used in conjunction with digital watermarking and steganographic encoding/decoding and payload interpretation methods. One claim recites a method for interpreting a data structure having fixed and variable message portions, the method comprising: processing the fixed message portion to determine a version of the variable message portion; decoding the entire payload field of the variable message portion according to the determined version; and interpreting only a portion of the decoded payload field according to the determined version. Of course, other features and claims are provided too.
1. A method for creating a payload in a data structure, comprising:
forming a fixed message portion comprising a validation field and a version field, in which the validation field and the version field each have a fixed bit-length, in which the validation field comprises a fixed set of message symbols that provide a check to determine whether a valid payload is present, in which the version field comprises a version identifier indicating a version associated with a variable message portion;
forming the variable message portion comprising an error detect field and a payload field, in which the error detect field comprises a plurality of error detect symbols, and in which the payload field comprises a payload item sub-type identifier that identifies a payload item conveyed in the payload field; and
embedding the fixed message portion and the variable message portion into a host media signal.
2. The method of claim 1 , wherein the data structure comprises a digital watermark.
3. The method of claim 1 , wherein said embedding comprises embedding such that the data structure is substantially imperceptible in the host media signal.
4. The method of claim 1 , wherein the payload item comprises at least one item selected from the group of: an identifier, a computer file, a set of machine-executable instructions, metadata, a date, a name, an address, and a location.
5. The method of claim 1 , wherein the version identifier includes a global trade item number (GTIN), an application identifier (Al), or a recycling code.
6. A method for interpreting a data structure comprising a message, the message comprising a fixed message portion and a variable message portion, the method comprising:
processing the fixed message portion to determine a version of the variable message portion, said processing yielding a determined version of the variable message portion, in which the variable message portion comprises a payload item sub-type identifier that identifies a sub-category associated with a payload item conveyed in a payload field;
decoding the payload field of the variable message portion according to the determined version of the variable message portion; and
interpreting the decoded payload field according to the payload item sub-type identifier.
7. The method of claim 1 in which the payload item comprises a sell-by date or expiration date.
8. The method of claim 1 in which the payload item sub-type identifier comprises plural bits.
9. The method of claim 1 in which the version identifier conveys a location of the payload item sub-type identifier within the variable message portion.
10. The method of claim 1 in which a location of the payload item sub-type identifier is independent of data conveyed by the version identifier.
11. The method of claim 1 in which the variable message portion comprises a plurality of payload item sub-type identifiers.
12. The method of claim 11 in which the version field conveys a number of the plurality of payload item sub-type identifiers.
13. The method of claim 1 in which the payload item sub-type identifier identifies the payload item by conveying a sub-category associated with the payload item.
14. The method of claim 1 in which the payload item sub-type identifier identifies the payload item by conveying a sub-category associated with the version identifier.
15. The method of claim 6 in which the payload item comprises a sell-by date or expiration date.
16. The method of claim 6 in which the payload item sub-type identifier comprises plural bits.
17. The method of claim 6 in which the determined version comprises plural bits and indicates a location of the payload item sub-type identifier within the variable message portion.
18. The method of claim 6 in which a location of the payload item sub-type identifier is independent of data conveyed by the determined version.
19. The method of claim 6 in which the variable message portion comprises a plurality of payload item sub-type identifiers.
20. The method of claim 19 in which the determined version comprises plural bits, and conveys a number of the plurality of payload item sub-type identifiers.
21. The method of claim 6 in which the payload item sub-type identifier identifies the payload item by conveying a sub-category associated with the payload item.
22. The method of claim 6 in which the payload item sub-type identifier identifies the payload item by conveying a sub-category associated with the determined version.