Abstract: Example apparatus disclosed herein include a watermark detector to detect watermarks in a media signal. Disclosed example apparatus also include a controller to operate the watermark detector to (1) detect a first watermark in the media signal, and (2) cycle between sleep intervals and active intervals based on a repetition rate of the watermarks in the media signal to perform a detection operation for a second watermark at a second location in the media signal relative to a first location of the first watermark in the media signal. In some examples, the controller is to search a buffer of prior detected watermark symbols to detect a third watermark at a third location prior to the second location in the media signal in response to the second watermark not being detected at the second location in the media signal.

Abstract: Methods and apparatus are disclosed for supplementing partially readable and/or inaccurate codes. An example apparatus includes a watermark analyzer to select a first watermark and a second watermark decoded from media; a comparator to compare a first decoded timestamp of the first watermark to a second decoded timestamp of the second watermark; and a timestamp adjuster to adjust the second decoded timestamp based on the first decoded timestamp of the second watermark when at least a threshold number of symbols of the second decoded timestamp match corresponding symbols of the first decoded timestamp.

Abstract: Methods, apparatus, systems and articles of manufacture to extend a timestamp range supported by a watermark without breaking backwards compatibility are disclosed. An example watermark encoder includes a counter to increment symbols of a watermark timestamp and a controller to control the counter to increment the symbols of the watermark timestamp based on a key, the controller to cause the counter to restrict ones of the symbol values to increment over one of a first range of symbol values or a second range of symbol values based on a value of the key, the second range of symbol values different from the first range of symbol values.

Abstract: An example apparatus includes at least one processor circuitry to execute or instantiate instructions to identify a media file is scheduled to be accessed by a media device within a first time period after a publishing of the media file was published by a media provider; select a first symbol to be inserted at a first symbol position and a second symbol to be inserted at a second symbol position to identify an access of the media file is to be accessed by the media device within the first time period, the first symbol position in a first bit sequence, the second symbol position in a second bit sequence; encode the first bit sequence in the media file on a first encoding layer of a multilayered watermark, and encode the second bit sequence in the media file on a second encoding layer of the multilayered watermark.

Abstract: Example apparatus disclosed herein include a watermark detector to detect watermarks in a media signal. Disclosed example apparatus also include a controller to operate the watermark detector to (1) detect a first watermark in the media signal, and (2) cycle between sleep intervals and active intervals based on a repetition rate of the watermarks in the media signal to perform a detection operation for a second watermark at a second location in the media signal relative to a first location of the first watermark in the media signal. In some examples, the controller is to search a buffer of prior detected watermark symbols to detect a third watermark at a third location prior to the second location in the media signal in response to the second watermark not being detected at the second location in the media signal.

Abstract: Methods and apparatus are disclosed for supplementing partially readable and/or inaccurate codes. An example apparatus includes a watermark analyzer to select a first watermark and a second watermark decoded from media; a comparator to compare a first decoded timestamp of the first watermark to a second decoded timestamp of the second watermark; and a timestamp adjuster to adjust the second decoded timestamp based on the first decoded timestamp of the second watermark when at least a threshold number of symbols of the second decoded timestamp match corresponding symbols of the first decoded timestamp.

Abstract: An example apparatus includes at least one processor circuitry to execute or instantiate instructions to identify a media file is scheduled to be accessed by a media device within a first time period after a publishing of the media file was published by a media provider; select a first symbol to be inserted at a first symbol position and a second symbol to be inserted at a second symbol position to identify an access of the media file is to be accessed by the media device within the first time period, the first symbol position in a first bit sequence, the second symbol position in a second bit sequence; encode the first bit sequence in the media file on a first encoding layer of a multilayered watermark, and encode the second bit sequence in the media file on a second encoding layer of the multilayered watermark.

Abstract: Methods, apparatus, systems and articles of manufacture to extend a timestamp range supported by a watermark without breaking backwards compatibility are disclosed. An example watermark encoder includes a counter to increment symbols of a watermark timestamp and a controller to control the counter to increment the symbols of the watermark timestamp based on a key, the controller to cause the counter to restrict ones of the symbol values to increment over one of a first range of symbol values or a second range of symbol values based on a value of the key, the second range of symbol values different from the first range of symbol values.

Abstract: Apparatus, systems, articles of manufacture, and methods for viewer authentication are disclosed. An example system comprises memory, first instructions, and processor circuitry to execute the first instructions to send one or more second instructions to the device, the second instructions to cause the device to trigger collection of audio metering data from a sensed audio signal based on a programming schedule that is to identify when the program is to be broadcast, the program associated with a first time duration, the audio metering data associated with a second time duration, accept voting data from the user for a ballot presented in the program, and transmit the audio metering data and the voting data, determine a level of exposure of the user to the program based on the first time duration and the second time duration, and adjust the voting data based on the level of exposure.

Abstract: Example apparatus disclosed herein include a watermark detector to detect watermarks in a media signal. Disclosed example apparatus also include a controller to operate the watermark detector to (1) detect a first watermark in the media signal, and (2) cycle between sleep intervals and active intervals based on a repetition rate of the watermarks in the media signal to perform a detection operation for a second watermark at a second location in the media signal relative to a first location of the first watermark in the media signal. In some examples, the controller is to search a buffer of prior detected watermark symbols to detect a third watermark at a third location prior to the second location in the media signal in response to the second watermark not being detected at the second location in the media signal.

Abstract: Methods, apparatus, systems, and articles of manufacture are disclosed to perform time alignment for watermarks. An example apparatus adjusts a power value of an element of a template based on respective average magnitudes and respective tonality ratios corresponding to a plurality of frequency representations of a media signal, the media signal to be encoded with at least one watermark, the element corresponding to one of the plurality of frequency representations. Additionally, the example apparatus computes an alignment of the template to the media signal based on respective power values of elements of the template, the template corresponding to a type of the at least one watermark. The example apparatus also encodes the media signal with the at least one watermark according to the alignment.

Abstract: Methods and apparatus are disclosed for supplementing partially readable and/or inaccurate codes. An example apparatus includes a watermark analyzer to select a first watermark and a second watermark decoded from media; a comparator to compare a first decoded timestamp of the first watermark to a second decoded timestamp of the second watermark; and a timestamp adjuster to adjust the second decoded timestamp based on the first decoded timestamp of the second watermark when at least a threshold number of symbols of the second decoded timestamp match corresponding symbols of the first decoded timestamp.

Abstract: Apparatus, systems, articles of manufacture, and methods for viewer authentication are disclosed. An example system comprises memory, first instructions, and processor circuitry to execute the first instructions to send one or more second instructions to the device, the second instructions to cause the device to trigger collection of audio metering data from a sensed audio signal based on a programming schedule that is to identify when the program is to be broadcast, the program associated with a first time duration, the audio metering data associated with a second time duration, accept voting data from the user for a ballot presented in the program, and transmit the audio metering data and the voting data, determine a level of exposure of the user to the program based on the first time duration and the second time duration, and adjust the voting data based on the level of exposure.

Abstract: Methods, apparatus, systems, and articles of manufacture to improve watermark detection in acoustic environments are disclosed. An example apparatus includes at least one memory, instructions in the apparatus, and processor circuitry to execute and/or instantiate the instructions to encode a first symbol in a media file at a first symbol position on a first encoding layer of a multilayered watermark, and encode a second symbol in the media file at a second symbol position on a second encoding layer of the multilayered watermark, the first encoding layer and the second encoding layer including a plurality of symbol positions, one or more of the plurality of the symbol positions on at least one of the first encoding layer or the second encoding layer to be empty.

Abstract: Methods and apparatus are disclosed for supplementing partially readable and/or inaccurate codes. An example apparatus includes a watermark analyzer to select a first watermark and a second watermark decoded from media; a comparator to compare a first decoded timestamp of the first watermark to a second decoded timestamp of the second watermark; and a timestamp adjuster to adjust the second decoded timestamp based on the first decoded timestamp of the second watermark when at least a threshold number of symbols of the second decoded timestamp match corresponding symbols of the first decoded timestamp.

Abstract: Methods, apparatus, systems and articles of manufacture to extend a timestamp range supported by a watermark without breaking backwards compatibility are disclosed. An example watermark encoder includes a counter to increment symbols of a watermark timestamp and a controller to control the counter to increment the symbols of the watermark timestamp based on a key, the controller to cause the counter to restrict ones of the symbol values to increment over one of a first range of symbol values or a second range of symbol values based on a value of the key, the second range of symbol values different from the first range of symbol values.

Abstract: Apparatus, systems, articles of manufacture, and methods for viewer authentication are disclosed. An example system includes processing circuitry to execute computer readable instructions to send one or more instructions to cause the user device to: trigger collection of audio metering data from a sensed audio signal based on a programming schedule that is to identify when the program is to be broadcast; accept voting data from the user for a ballot presented in the program; transmit the audio metering data; and transmit the voting data. The processing circuitry also is to determine a level of exposure of the user to the program based on the audio metering data received from the user device; calculate a weighting score based on the level of exposure; and adjust the voting data based on the weighting score.

Abstract: Methods and apparatus are disclosed for supplementing partially readable and/or inaccurate codes. An example apparatus includes a watermark analyzer to select a first watermark and a second watermark decoded from media; a comparator to compare a first decoded timestamp of the first watermark to a second decoded timestamp of the second watermark; and a timestamp adjuster to adjust the second decoded timestamp based on the first decoded timestamp of the second watermark when at least a threshold number of symbols of the second decoded timestamp match corresponding symbols of the first decoded timestamp.

Abstract: Example apparatus disclosed herein include a watermark detector to detect watermarks in a media signal. Disclosed example apparatus also include a controller to operate the watermark detector to (1) detect a first watermark in the media signal, and (2) cycle between sleep intervals and active intervals based on a repetition rate of the watermarks in the media signal to perform a detection operation for a second watermark at a second location in the media signal relative to a first location of the first watermark in the media signal. In some examples, the controller is to search a buffer of prior detected watermark symbols to detect a third watermark at a third location prior to the second location in the media signal in response to the second watermark not being detected at the second location in the media signal.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to implement power efficient detection of watermarks in media signals are disclosed. Example metering apparatus disclosed herein include detector means for detecting watermarks in a media signal. Disclosed example metering apparatus also include controller means for operating the detector means to (1) detect a first watermark in the media signal, and (2) cycle between sleep intervals and active intervals to detect a second watermark at a second location in the media signal relative to a first location of the first watermark in the media signal after the first watermark has been verified.