| CPC G10L 19/018 (2013.01) | 20 Claims |

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1. A method 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 method comprising:
engaging, by a computing system, 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, by the computing system, 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, by the computing system, 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.
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