Abstract: Methods and apparatus for determining increasing robustness of media signatures are disclosed. An example apparatus includes a characteristic analyzer to determine a first difference between (A) a first characteristic of an audio signal at a first time and (B) a second characteristic of the audio signal at a second time.

Abstract: Methods, apparatus, systems and articles of manufacture to reduce signature matching uncertainty in media monitoring systems are disclosed. Disclosed example apparatus are to compare first groups of monitored signatures representative of monitored media with second groups of reference signatures representative of respective reference media to determine a first sequence of match results for an observation period, the first and second groups to have a first size corresponding to a first number of signatures. Disclosed example apparatus are also to compare, in response to a discontinuity in the first sequence of signature match results, third groups of monitored signatures from the sequence of monitored signatures with fourth groups of reference signatures from the respective sequences of reference signatures to determine a second sequence of signature match results for the observation period, the third groups and the fourth groups to have a second size greater than the first size.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed for scalable architectures for reference signature matching and updating. An example method for scalable architectures for reference signature matching and updating includes accessing site signatures to be compared to reference signatures from a first group of media sources. The example method also include determining if a first reference node is an owner of a first one of the site signatures, comparing a neighborhood of site signatures including the first site signature to reference signatures in a first subset of reference signatures when the first reference node is the owner of the first site signature, the first subset of references signatures stored in a first memory partition associated with the first reference node, and not comparing site signature to reference signatures when the first reference node is not the owner of the first one of the site signatures.

Abstract: Methods and apparatus to analyze microphone placement for watermarks and signatures are disclosed. An example instructions cause one or more processors to at least determine a variance of a magnitude spectrum of a frequency band corresponding to a frequency spectrum of a first audio signal sensed with an audio sensor. The example instructions further cause the one or more processors to determine, based on the variance, a recovery rate associated with at least one of watermark detection or signature generation to be performed on a second audio signal to be sensed with the audio sensor.

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: Methods, apparatus and articles of manufacture (e.g., computer readable media) to detect watermark modifications are disclosed. Example apparatus disclosed herein include means for encoding a first watermark in a first media signal obtained from an output of a media device to obtain a second media signal encoded with the first watermark and a second watermark, the second watermark already encoded in the first media signal obtained from the output of the media device. Disclosed example apparatus also include means for decoding the first watermark and the second watermark from the second media signal to determine a first metric corresponding to the first watermark and a second metric corresponding to the second watermark. Disclosed example apparatus further include means for outputting, based on the first metric and the second metric, an indication of whether the second watermark has been modified.

Abstract: Example methods, apparatus and articles of manufacture to provide media content are disclosed. Example apparatus disclosed herein include means for identifying primary media content presented on a first media presentation device. Disclosed example apparatus also include means for accessing a secondary content schedule associated with the primary media content. The secondary content schedule includes a plurality of secondary content items and time values associated with the secondary content items. The secondary content items are also associated with a loyalty value for a user of the first media presentation device. Disclosed example apparatus further include means for selecting one of the secondary content items to be accessed in response to a timestamp associated with the primary media content being between time values associated with the selected one of the secondary content items in the secondary content schedule.

Abstract: Example apparatus disclosed include means for detecting encoded information present in audio obtained from a media presentation device, means for generating a signature of the audio, and means for determining an on/off state of the media presentation device based on a gain level, the means for determining to determine the on/off state based on the encoded information detected in the audio or the signature generated from the audio. Disclosed example apparatus also include means for crediting a portion of the audio to first media based on the encoded information or the signature, the means for crediting to credit the audio by overriding (i) a first determination that the media presentation device was in the off state during collection of the audio with (ii) a second determination that the media presentation device was in the on state based on the collection of the audio.

Abstract: Methods and apparatus to perform audio watermarking and watermark detection and extraction are disclosed. Example apparatus include means for transforming an audio signal into a frequency domain representation, and means for determining characteristics of frequencies of the frequency domain representation that may contain the code. In some examples, the means for determining is to normalize the characteristics of the frequencies of the frequency domain representation in respective ones of the code bands that may contain the code to determine normalized characteristics of the frequencies representative of the code, a respective one of the code bands that may contain the code to be normalized against a first characteristic of a first frequency in that code band; sum the normalized characteristics of the frequencies representative of the code; determine the sum is representative of the code when the sum satisfies a threshold; and validate the code based on an encoding scheme.

Abstract: Methods, apparatus, systems and articles of manufacture to perform speed-enhanced playback of recorded media are disclosed. Example media playback devices disclosed herein are to determine a target number of frames of recorded media to drop during playback of the recorded media, the target number determined based on a difference between (1) a total number of frames of the recorded media and (2) a ratio of the total number of frames of the recorded media to a target playback rate. Disclosed example media playback devices are also to select a subset of the frames of the recorded media to drop during the playback of the recorded media, the frames selector to select the subset of the frames based on the target number of frames to drop and skip bytes included in the subset of frames.

Abstract: Methods, apparatus, systems and articles of manufacture to reduce signature matching uncertainty in media monitoring systems are disclosed. Disclosed example apparatus are to compare first neighborhoods of monitored signatures representative of monitored media with second neighborhoods of reference signatures representative of respective reference media to determine a first sequence of matching results for an observation period, the first and second neighborhoods to have respective sizes that span a first number of signatures.

Abstract: Methods and apparatus to count people are disclosed. Example apparatus disclosed herein include means for discarding existing characteristic datasets from a list; means for populating the list with first characteristic datasets obtained from a first plurality of images representative of an environment during a first period of time of a media presentation; means for limiting a number of the first characteristic datasets stored in the list for a first location represented in the first plurality of images; and means for comparing the first characteristic datasets to each other to determine a first number of unique faces in the environment during the first period of time, wherein the means for discarding is to delete the first characteristic datasets from the list, and the means for populating is to re-populate the list with second characteristic datasets obtained from a second plurality of images representative of the environment.

Abstract: Methods and apparatus for crediting a media presentation device are disclosed. Example apparatus disclosed include means for computing a signature from audio obtained from a media device, means for determining an on/off state of the media device based on a gain level, means for crediting the media device with presenting media when (1) the signature matches at least one of a set of reference signatures and the on/off state determined for the media device is an on state, and (2) when the signature matches at least one of the set of reference signatures and the on/off state determined for the media device is an off state, the means for crediting to not credit the media device with presenting the media when (3) the signature does not match at least one of the set of reference signatures and the on/off state determined for the media device is the off state.

Abstract: Methods and apparatus to analyze microphone placement for watermarks and signatures are disclosed. An example apparatus includes a microphone. The example apparatus further includes a meter to convert a noise burst detected by the microphone to a digital signal. The example apparatus further includes a signal transformer to determine a frequency spectrum of the digital signal. The example apparatus further includes a processor to determine a variance of a magnitude spectrum of a frequency band corresponding to the frequency spectrum and determine, based on the variance, a recovery rate associated with at least one of watermark detection or signature generation to be performed on an audio signal detected by the microphone.

Abstract: Example apparatus disclosed herein include a memory and a processor to execute instructions to identify a first set of face rectangles and a second set of face rectangles in a frame pair of image data corresponding to a media environment, the first set of face rectangles corresponding to a first image sensor and the second set of face rectangles corresponding to a second image sensor, remove first face rectangles from the first set of face rectangles and the second set of face rectangles when the first face rectangles are determined to correspond to false positive face detections, group second face rectangles that remain in the first set of face rectangles and the second set of face rectangles after removal of the first face rectangles to form groups of face rectangles, and generate a count of people identified in the media environment based on a number of the groups.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed for scalable architectures for reference signature matching and updating. An example method for scalable architectures for reference signature matching and updating includes accessing site signatures to be compared to reference signatures from a first group of media sources. Determining if a first reference node is an owner of a first one of the site signatures. Comparing a neighborhood of site signatures including the first site signature to reference signatures in a first subset of reference signatures when the first reference node is the owner of the first site signature, the first subset of references signatures stored in a first memory partition associated with the first reference node. Not comparing site signature to reference signatures when the first reference node is not the owner of the first one of the site signatures.

Abstract: Methods, apparatus and articles of manufacture (e.g., computer readable media) to detect watermark modifications are disclosed. Example apparatus disclosed herein are to encode a first watermark in a first media signal to obtain a second media signal, the first watermark associated with a first watermark layer. Disclosed example apparatus are also to determine, from the second media signal, a first metric corresponding to the first watermark. Disclosed example apparatus are further to determine, from the second media signal, a second metric corresponding to a second watermark encoded in the second media signal, the second watermark associated with a second watermark layer different from the first watermark layer. Disclosed example apparatus are also to output, based on the first metric and the second metric, an indication of whether the second watermark has been modified.

Abstract: Methods and apparatus to determine a state of a media presentation device are disclosed. Example disclosed methods include generating a first set of weighted coefficients based on first audio received by first and second microphones at a first time. Example disclosed methods include generating a second set of weighted coefficients based on second audio received by the first and second microphones at a second time after the first time. Example disclosed methods include comparing the first set of coefficients and the second set of coefficients to generate a similarity value. Example disclosed methods include, when the similarity value satisfies a threshold, determining that the media presentation device is in a first state. Example disclosed methods include, when the similarity value does not satisfy the threshold, determining that the media presentation device is in a second state.

Abstract: Methods and apparatus for determining increasing robustness of media signatures are disclosed. An example apparatus includes a characteristic analyzer to determine a first difference between (A) a first characteristic of an audio signal at a first time and (B) a second characteristic of the audio signal at a second time.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to detect media watermarks in magnetic field data are disclosed herein. Example media monitors disclosed herein include a magnetic field estimator to determine first magnetic field data, the magnetic field estimator in communication with a magnetometer. Disclosed example media monitors also include a correlator to correlate the first magnitude field data with a reference sequence to determine second magnetic field data. Disclosed example media monitors further include a watermark decoder to process the second magnetic field data to detect an audio watermark encoded in an audio signal.