Use of Symbol Strength and Verified Watermark Detection as Basis to Improve Media-Exposure Detection

A computing system comprising:

• at least one processor;
• at least one non-transitory data storage;
• and
• program instructions stored in the at least one non-transitory data storage and executable by the at least one processor to carry out operations for extracting an identifier value encoded in a given watermark in media content having a sequence of watermarks, wherein each watermark in the sequence of watermarks spans a watermark duration defining a sequence of symbol time segments and encodes a respective identifier value by including a sequence of symbols respectively in the sequence of symbol time segments, each symbol having a respective tone combination that corresponds with a respective symbol value, the operations including:
• engaging in an identifier-determination process including (i) for each symbol time segment in the sequence of symbol time segments of the given watermark, evaluating tone strength to determine a candidate symbol value based on a finding that a strongest set of tones in the symbol time segment corresponds with the candidate symbol value and (ii) determining the identifier value to be a sequence of symbol values based on the determined candidate symbol values of the sequence of symbol time segments,
• assigning a quality level to the given watermark, including (i) classifying as erroneous, based on one or more rules regarding watermark structure, one or more of the determined candidate symbol values and (ii) assigning the quality level based on how many of the determined candidate symbol values are classified as erroneous, and
• responsive to at least the assigned quality level being threshold low, engaging in an error-correction process including (i) making a determination that at least each symbol time segment in the given watermark whose candidate symbol value is classified as erroneous has a threshold strong tone combination matching the tone combination that represents the symbol value of a corresponding symbol time segment in a verified watermark and (ii) responsive to the determination, correcting the determined identifier value of the given watermark to be the identifier value of the verified watermark.

At least one non-transitory computer-readable medium having stored thereon program instructions executable by at least one processor to carry out operations extracting an identifier value encoded in a given watermark in media content having a sequence of watermarks, wherein each watermark in the sequence of watermarks spans a watermark duration defining a sequence of symbol time segments and encodes a respective identifier value by including a sequence of symbols respectively in the sequence of symbol time segments, each symbol having a respective tone combination that corresponds with a respective symbol value, the operations including:

• engaging in an identifier-determination process including (i) for each symbol time segment in the sequence of symbol time segments of the given watermark, evaluating tone strength to determine a candidate symbol value based on a finding that a strongest set of tones in the symbol time segment corresponds with the candidate symbol value and (ii) determining the identifier value to be a sequence of symbol values based on the determined candidate symbol values of the sequence of symbol time segments;
• assigning a quality level to the given watermark, including (i) classifying as erroneous, based on one or more rules regarding watermark structure, one or more of the determined candidate symbol values and (ii) assigning the quality level based on how many of the determined candidate symbol values are classified as erroneous;
• and
• responsive to at least the assigned quality level being threshold low, engaging in an error-correction process including (i) making a determination that at least each symbol time segment in the given watermark whose candidate symbol value is classified as erroneous has a threshold strong tone combination matching the tone combination that represents the symbol value of a corresponding symbol time segment in a verified watermark and (ii) responsive to the determination, correcting the determined identifier value of the given watermark to be the identifier value of the verified watermark.