Formation and analysis of signals with common and transaction watermarks

A method for analyzing a watermarked signal with at least one common watermark that identifies a distributor thereof, the method comprising the steps of:

• using the common watermark to recover a plurality of transaction watermarks of the watermarked signal that define respective symbols thereof;
• providing at least one hypothesis transaction code that defines respective symbols thereof;
• comparing the symbols of the transaction watermarks to corresponding symbols of the hypothesis transaction code to determine a correspondence therebetween;
• and
• based on said correspondence, determining a probability that the hypothesis transaction code matches a transaction code that is associated with at least some of the transaction watermarks.

An apparatus for analyzing a watermarked signal with at least one common watermark that identifies a distributor thereof, the apparatus comprising:

• a detector which uses the common watermark to recover a plurality of transaction watermarks of the watermarked signal that define respective symbols thereof;
• storage for providing at least one hypothesis transaction code that defines respective symbols thereof;
• a comparator for comparing the symbols of the transaction watermarks to corresponding symbols of the hypothesis transaction code to determine a correspondence therebetween;
• and
• an hypothesis testing block for determining, based on said correspondence, a probability that the hypothesis transaction code matches a transaction code that is associated with at least one of the transaction watermarks.

A method for analyzing content that is distributed via a plurality of distribution points in a network, comprising the steps of:

• obtaining the content from the plurality of distribution points;
• retrieving a common watermark from the content;
• determining, for each of the distribution points, whether the retrieved common watermark corresponds to a predetermined common watermark code;
• and
• for the content that comprises the retrieved common watermark that corresponds to the predetermined common watermark code:
• retrieving a transaction watermark from the content, and
• identifying a transaction code associated with the transaction watermark.

An apparatus for analyzing content that is distributed via a plurality of distribution points in a network, comprising:

• a crawler for obtaining the content from the plurality of distribution points;
• a common watermark detector for retrieving a common watermark from the content and determining, for each of the distribution points, whether the retrieved common watermark corresponds to a predetermined common watermark code;
• and
• a forensic analysis block for retrieving a transaction watermark from the content, and identifying a transaction code associated with the transaction watermark, for the content that comprises the retrieved common watermark that corresponds to the predetermined common watermark code.

A method for analyzing a watermarked signal comprising the steps of:

• recovering a plurality of transaction watermarks of the watermarked signal that define respective symbols thereof,
• providing a plurality of hypothesis transaction codes that define respective symbols thereof;
• for each hypothesis transaction code, comparing the symbols of the transaction watermarks to corresponding symbols of the hypothesis transaction code to determine a correspondence therebetween;
• for each hypothesis transaction code, determining a probability based on the correspondence thereof that the hypothesis transaction code matches a transaction code that is associated with at least some of the transaction watermarks;
• and
• recovering a content identifier from the watermarked signal for use in selecting the plurality of hypothesis codes from a transaction code database wherein the content identifier is determined according to common watermark that are interleaved with the transaction watermarks in the watermarked signal.

A method for analyzing content that is distributed via a plurality of distribution points in a network, comprising the steps of:

• obtaining a first duration of the content from the plurality of distribution points;
• determining, for each of the distribution points, whether the first duration of content comprises a common watermark that corresponds to a predetermined common watermark code;
• and
• for the content that comprises the common watermark that corresponds to the predetermined common watermark code:
• obtaining a second duration of the content from the plurality of distribution points;
• retrieving a transaction watermark from the second duration of the content, and
• identifying a transaction code associated with the transaction watermark.