Content serialization by varying content properties, including varying master copy watermark properties
This disclosure describes novel methods for generating unique copies of content. One method combines the functions of the master copy and unique copy watermarks. In particular, the method generates a unique copy by varying the manner in which the master copy watermark is embedded in unique copies of a content item. In one embodiment, the master copy watermark is repeated within the content item and its location is varied in a unique pattern that comprises the unique copy watermark. The unique copy is generated by producing a copy in which master copy watermarks are embedded in a unique pattern. For instance in one embodiment, the locations of the master copy watermarks in the content item are represented as a vector of delta values in which each delta value corresponds to the distance between a corresponding instance of the master copy watermark, and a neighboring instance of the master copy watermark. This vector is stored in a transaction record in association with transaction information, such as information identifying the master copy and information associated with the unique copy. Other ways of representing the unique pattern of attributes of the master copy watermark are also possible. In other embodiments, properties of the master copy watermark other than its location are varied through the content. The unique copy watermark is conveyed in the vector of deltas in these properties of the master copy watermark. Some examples of these properties of the master copy watermark signal include phase characteristics (e.g., the phase shift of a watermark carrier signal), frequency magnitude characteristics, etc. These properties are varied in a manner that does not alter the information carried in the master copy watermark. However, it does provide a variation that creates a unique copy, and the unique copy watermark is conveyed in this variation. The variation in location of the instances of the master copy watermark can be in different domains, such as a spatial domain, a time domain, a time-space domain, a transform domain (including frequency transform domains), a compressed domain, etc.
1. A method of serializing a content item comprising:
analyzing a master copy of the content item stored in an electronic memory to determine parameters for embedding a master copy watermark in the content item, the master copy watermark conveying digital information within the content item that is common for copies of the content item; and
from a master copy of the content item stored in an electronic memory, generating a unique copy of the content item by altering the master copy watermark, the alterations forming a pattern that comprises a unique copy watermark, wherein the alterations comprise variations in embedding the master copy watermark; and storing the unique copy in an electronic memory, the unique copy including the master copy watermark and the pattern comprising the unique copy watermark.
2. The method of claim 1 wherein the alterations comprise variations in a property of the master copy watermark that is embedded at locations in the content item.
3. The method of claim 2 wherein the locations comprise frequency locations.
4. The method of claim 2 wherein the locations comprise temporal locations.
5. The method of claim 2 wherein the variations comprise removal of a component of the master copy watermark.
6. A non-transitory computer readable medium on which is stored instructions, which, when executed by a computer, perform a method of serializing a content item comprising:
analyzing a master copy of the content item to determine parameters for embedding a master copy watermark, the master copy watermark conveying digital information that is common for copies of the content item; and
generating a unique copy of the content item from a master copy by altering the master copy watermark, the alterations forming a pattern that comprises a unique copy watermark, wherein the alterations comprise variations in embedding the master copy watermark.
7. The computer readable medium of claim 6 wherein the alterations comprise variations in a property of the master copy watermark that is embedded at locations determined through analysis of the master copy of the content item.
8. The computer readable medium of claim 7 wherein the locations comprise frequency locations.
9. The computer readable medium of claim 7 wherein the locations comprise temporal locations.
10. The computer readable medium of claim 7 wherein the variations comprise removal of a component of the master copy watermark.