Abstract: Methods, apparatus, systems and articles of manufacture are disclosed for watermarking using starting phase modulation. An example method disclosed herein includes calculating a first instantaneous phase value for a first watermark component of a watermarked media signal at a first time, calculating a second instantaneous phase value for a second watermark component, determining a first sum of differences for the first and second instantaneous phase values relative to a first possible starting phase value, determining a second sum of differences for the first and second instantaneous phase values relative to a second possible starting phase value, selecting a corresponding one of the first possible starting phase value or the second possible starting phase value to be a starting phase value, decoding a bit value corresponding to the starting phase value, determining a payload based on the bit value and a symbol represented by watermark components.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed for watermarking using starting phase modulation. An example method disclosed herein includes calculating a first instantaneous phase value for a first watermark component of a watermarked media signal at a first time, calculating a second instantaneous phase value for a second watermark component, determining a first sum of differences for the first and second instantaneous phase values relative to a first possible starting phase value, determining a second sum of differences for the first and second instantaneous phase values relative to a second possible starting phase value, selecting a corresponding one of the first possible starting phase value or the second possible starting phase value to be a starting phase value, decoding a bit value corresponding to the starting phase value, determining a payload based on the bit value and a symbol represented by watermark components.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed for associating different watermarks detected in media. An example method disclosed herein includes determining whether a first watermark detected in a media signal is represented in a watermark data structure and associating the first watermark with a first media presentation record associated with a second watermark in response to the first watermark being associated in the watermark data structure with the second watermark. The example method further includes transmitting monitoring data including the first media presentation record to an audience measurement entity.

Abstract: Apparatus, systems, articles of manufacture, and methods to identify media using watermarks and signatures are disclosed. An example apparatus includes a watermark evaluator to determine a category indicated by a watermark detected in the media. The example apparatus also includes a signature comparator to compare a query signature with a subset of reference signatures associated with the category to identify the media, the query signature generated from the media, the reference signatures generated from reference media associated with the category.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to extend a time range supported by a watermark are disclosed. Example watermark encoding apparatus disclosed herein include a timestamp cycle evaluator to determine which one of a plurality of timestamp cycles is to be represented by a timestamp of a watermark. Disclosed example watermark encoding apparatus also include a symbol swapper to swap at least two symbols of the watermark when the timestamp is to represent a second one of the timestamp cycles but not to swap the at least two symbols of the watermark when the timestamp is to represent a first one of the timestamp cycles. Disclosed example watermark encoding apparatus further include a watermark embedder to embed the watermark in a first piece of media.

Abstract: Methods and apparatus to audio watermarking and watermark detection and extracted are described herein. An example method includes receiving a media content signal, sampling the media content signal to generate samples, storing the samples in a buffer, determining a first sequence of samples in the buffer, determining a second sequence of samples in the buffer, wherein the second sequence of samples is of substantially equal length as the first sequence of samples, calculating an average of the first sequence of samples and the second sequence of samples to generate an average sequence of samples, extracting an identifier from the average sequence of samples, and storing the identifier in a tangible memory.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to extend a time range supported by a watermark are disclosed. Example watermark encoding apparatus disclosed herein include a timestamp cycle evaluator to determine which one of a plurality of timestamp cycles is to be represented by a timestamp of a watermark, the timestamp including a set of timestamp symbols. Disclosed example watermark encoding apparatus also include a symbol modifier to modify a subset of data symbols of the watermark based on a further timestamp symbol not included in the set of timestamp symbols of the timestamp, the further timestamp symbol identifying the one of the timestamp cycles to be represented by the timestamp of the watermark. Disclosed example watermark encoding apparatus further include a watermark embedder to embed the watermark in a first piece of media.

Abstract: Apparatus, systems, articles of manufacture, and methods to identify media using watermarks and signatures are disclosed. An example apparatus includes a watermark evaluator to determine a time and a category indicated by a watermark detected in the media and a window generator to determine a search window based on the time indicated by the watermark. The example apparatus also includes a signature comparator to compare a query signature having a time value within the search window with a subset of reference signatures associated with the category to identify the media, the query signature generated from the media, the subset set of reference signatures generated from reference media associated with the category.

Abstract: Methods, apparatus, systems and articles of manufacture to count people in an audience are disclosed. An example system includes means for transmitting a control signal to a portable device a threshold period of time after a person logs into a people meter separate from the portable device. The control signal causes the portable device to begin collecting location information and proximity information. The system also includes means for analyzing the location information to determine a location result indicative of a location of the portable device. The system further includes means for analyzing the proximity information to determine a proximity result indicative of whether the person is near the portable device. The location result and the proximity result collectively define first presence information. The first presence information indicative of whether the person is present in a media exposure environment associated with a media presentation device.

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 and apparatus to audio watermarking and watermark detection and extracted are described herein. Disclosed example methods to decode a watermark from an audio signal include averaging a second sequence of audio samples stored in a buffer with a first sequence of audio samples stored in the buffer to determine an averaged sequence of audio samples, the second sequence of audio samples being related to the first sequence of audio samples based on a repetition period associated with watermark data of the watermark to be decoded. Disclosed example methods also include determining whether to enable a stacker. Disclosed example methods further include, in response to the stacker being enabled, decoding the watermark from the averaged sequence of audio samples, and in response to the stacker being disabled, decoding the watermark from the first sequence of audio samples.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to extend a time range supported by a watermark are disclosed. Example watermark encoding apparatus disclosed herein include a timestamp cycle evaluator to determine which one of a plurality of timestamp cycles is to be represented by a timestamp of a watermark, the timestamp including a set of timestamp symbols. Disclosed example watermark encoding apparatus also include a symbol modifier to modify a subset of data symbols of the watermark based on a further timestamp symbol not included in the set of timestamp symbols of the timestamp, the further timestamp symbol identifying the one of the timestamp cycles to be represented by the timestamp of the watermark. Disclosed example watermark encoding apparatus further include a watermark embedder to embed the watermark in a first piece of media.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to extend a time range supported by a watermark are disclosed. Example watermark encoding apparatus disclosed herein include a timestamp cycle evaluator to determine which one of a plurality of timestamp cycles is to be represented by a timestamp of a watermark. Disclosed example watermark encoding apparatus also include a symbol swapper to swap at least two symbols of the watermark when the timestamp is to represent a second one of the timestamp cycles but not to swap the at least two symbols of the watermark when the timestamp is to represent a first one of the timestamp cycles. Disclosed example watermark encoding apparatus further include a watermark embedder to embed the watermark in a first piece of media.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to utilize audio watermarking for people monitoring are disclosed. Example people monitoring methods disclosed herein include determining, at a user device, whether a first trigger condition for emitting an audio watermark identifying at least one of the user device or a user of the user device is satisfied. Such example methods also include, in response to determining that the first trigger condition is satisfied, providing a first audio signal including the audio watermark to an audio circuit that is to output an acoustic signal from the user device.

Abstract: A method for generating a signature is disclosed. As part of the method, a first number of bits are identified in respective rows of an audio signature matrix that are determined to be the strongest bits in the row, bits of the audio signature matrix are replaced with respective cells having values depending on whether the respective bits are included in the first number of bits, a set of uniformly distributed numbers are generated within a range of numbered locations corresponding to cells of the audio signature matrix; numerical distances are determined, from respective numbers in the set of uniformly distributed numbers, to the numbered locations of the matrix, associated with nearest occurrences of a first value. A set of integers is generated based on the distances.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to utilize audio watermarking for people monitoring are disclosed. Example people monitoring methods disclosed herein include determining, at a user device, whether a first trigger condition for emitting an audio watermark identifying at least one of the user device or a user of the user device is satisfied. Such example methods also include, in response to determining that the first trigger condition is satisfied, providing a first audio signal including the audio watermark to an audio circuit that is to output an acoustic signal from the user device.

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 monitoring apparatus disclosed herein include means for transforming magnitude values of magnetic field data to a frequency domain to determine transformed magnetic field data, the magnetic field data associated with a first sampling rate, the magnetic field data obtained from a sensor. Disclosed example media monitoring apparatus also include means for detecting an audio watermark in a portion of the transformed magnetic field data associated with a first frequency, the audio watermark encoded in an audio signal, the audio watermark to have a frequency component associated with a second frequency different from the first frequency, the first frequency to be aliased relative to the second frequency based on the first sampling rate.

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 monitoring methods disclosed herein include accessing magnetic field data determined by a magnetometer, the magnetic field data associated with a first sampling rate. Disclosed example methods also include transforming magnitude values of the magnetic field data to a frequency domain to determine transformed magnetic field data. Disclosed example methods further include evaluating a portion of the transformed magnetic field data associated with a first frequency to detect a media watermark having a frequency component associated with a second frequency different from the first frequency, the first frequency being aliased relative to the second frequency based on the first sampling rate.

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 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.