Abstract: Example apparatus disclosed herein are to obtain a first hash key, a second hash key and a third hash key representative of first reference media in response to a first query of a first table, the second hash key associated with a second time preceding a first time associated with the first hash key, the third hash key associated with a third time following the first time associated with the first hash key. Disclosed example apparatus are also to prequalify the first hash key as a candidate for subsequent signature processing associated with a first site signature in response to a determination that the second hash key corresponds to a second site signature preceding the first site signature in time and that the third hash key corresponds to a third site signature following the first site signature in time.

Abstract: An example apparatus includes a first query processor to obtain a first hash key, first qualifier data and first value data associated with the first hash key, the first value data including a second hash key and a third hash key; a candidate qualifier to use the first value data to prequalify the first hash key as a candidate for subsequent signature processing associated with a first site signature, the candidate qualifier to: determine prequalification of the first hash key is successful in response to a determination that the second hash key matches a second site signature preceding the first site signature in time and that the third hash key matches a third site signature following the first site signature in time; and determine the prequalification of the first hash key is unsuccessful in response to a determination that at least one of the second hash key fails to match the second site signature or the third hash key fails to match the third site signature.

Abstract: An example apparatus includes a first query processor to obtain a first hash key, first qualifier data and first value data associated with the first hash key, the first value data including a second hash key and a third hash key; a candidate qualifier to use the first value data to prequalify the first hash key as a candidate for subsequent signature processing associated with a first site signature, the candidate qualifier to: determine prequalification of the first hash key is successful in response to a determination that the second hash key matches a second site signature preceding the first site signature in time and that the third hash key matches a third site signature following the first site signature in time; and determine the prequalification of the first hash key is unsuccessful in response to a determination that at least one of the second hash key fails to match the second site signature or the third hash key fails to match the third site signature.

Abstract: An example apparatus includes means for querying a first table to perform a first query of the first table using a hash corresponding to a first site signature, the first table including hash keys corresponding to respective reference signatures, the first query to obtain, from the first table, first qualifier data descriptive of a first reference signature corresponding to a first hash key; means for querying a second table to perform a second query of the second table, the second query to obtain a plurality of blocks of reference signatures; means for comparing a first block of site signatures with the plurality of blocks of reference signatures, the first block of site signatures to include the first site signature; and means for crediting media as corresponding to reference media represented by the first reference signature when the first block of site signatures matches the plurality of blocks of reference signatures.

Abstract: An example apparatus includes means for querying a first table to perform a first query of the first table using a hash corresponding to a first site signature, the first table including hash keys corresponding to respective reference signatures, the first query to obtain, from the first table, first qualifier data descriptive of a first reference signature corresponding to a first hash key; means for querying a second table to perform a second query of the second table, the second query to obtain a plurality of blocks of reference signatures; means for comparing a first block of site signatures with the plurality of blocks of reference signatures, the first block of site signatures to include the first site signature; and means for crediting media as corresponding to reference media represented by the first reference signature when the first block of site signatures matches the plurality of blocks of reference signatures.

Abstract: Methods, apparatus and articles of manufacture for signature retrieval and matching for media monitoring are disclosed. An example apparatus includes a hash table populator to store hash keys of reference signatures included in a reference signature block associated with reference media in entries of a hash table, and store qualifier data in the entry of the hash table, the qualifier data including a timestamp, an offset, and an identifier associated with the reference signature of the hash key. The apparatus further including a block table populator to store a block table key corresponding to the reference signature block in the entry of a block table, the block table key including the timestamp and the identifier, and store the reference signature block, a preceding reference signature block and a subsequent reference signature block in the first entry of the block table.

Abstract: Methods, apparatus and articles of manufacture for signature retrieval and matching for media monitoring are disclosed. An example apparatus includes a hash table populator to store hash keys of reference signatures included in a reference signature block associated with reference media in entries of a hash table, and store qualifier data in the entry of the hash table, the qualifier data including a timestamp, an offset, and an identifier associated with the reference signature of the hash key. The apparatus further including a block table populator to store a block table key corresponding to the reference signature block in the entry of a block table, the block table key including the timestamp and the identifier, and store the reference signature block, a preceding reference signature block and a subsequent reference signature block in the first entry of the block table.

Abstract: Methods, apparatus, systems and articles of manufacture to perform signature retrieval and matching for media monitoring are disclosed. Example methods disclosed herein can include querying a first table using a first site signature obtained from a monitored site, the first table including hash keys corresponding to respective reference signatures, the first table further including respective qualifier data descriptive of respective ones of the reference signatures, Such example methods can also include querying a second table using first qualifier data obtained from querying the first table using the first site signature, the first qualifier data descriptive of a first reference signature corresponding to a first hash key determined to match the first site signature. Such example methods can further include comparing a first block of site signatures with a portion of a plurality of blocks of reference signatures obtained from querying the second table using the first qualifier data.

Abstract: Methods, apparatus, systems and articles of manufacture to perform signature retrieval and matching for media monitoring are disclosed. Example methods disclosed herein can include querying a first table using a first site signature obtained from a monitored site, the first table including hash keys corresponding to respective reference signatures, the first table further including respective qualifier data descriptive of respective ones of the reference signatures, Such example methods can also include querying a second table using first qualifier data obtained from querying the first table using the first site signature, the first qualifier data descriptive of a first reference signature corresponding to a first hash key determined to match the first site signature. Such example methods can further include comparing a first block of site signatures with a portion of a plurality of blocks of reference signatures obtained from querying the second table using the first qualifier data.