Abstract: Example methods, apparatus, systems and articles of manufacture to implement down-mixing compensation for audio watermarking are disclosed. Example watermark embedding methods disclosed herein include determining a first attenuation factor associated with a first audio channel of a multi-channel audio signal based on first down-mixed audio samples obtained from down-mixing the first audio channel and a second audio channel of the multi-channel audio signal, determining a second attenuation factor associated with a third audio channel of the multi-channel audio signal based on second down-mixed audio samples obtained from down-mixing the second audio channel and the third audio channel of the multi-channel audio signal, selecting one of the first attenuation factor or the second attenuation factor to be a third attenuation factor associated with the second audio channel of the multi-channel audio signal, and embedding a watermark in the second audio channel based on the third attenuation factor.

Abstract: Methods and apparatus to present supplemental media on a second screen are disclosed. An example method includes establishing a connection between a digital media device and a computing device based on information identifying the computing device and, in response to establishing the connection, enabling the digital media device to skip a first type of media during a time-shifted presentation of media. The skipping is responsive to a command from a remote control device different than the computing device.

Abstract: Example methods, apparatus, systems and articles of manufacture to implement down-mixing compensation for audio watermarking are disclosed. Example watermark embedding methods disclosed herein include determining respective attenuation factors for a plurality of audio bands based on energy values associated with down-mixed audio samples corresponding to a first audio channel of a multi-channel audio signal and a second audio channel of the multi-channel audio signal. Disclosed example watermark embedding methods also include embedding a watermark in audio samples of the first audio channel based on the attenuation factors.

Abstract: Methods, apparatus, systems and articles of manufacture to count people in an audience are disclosed. An example method includes analyzing location information collected by a portable device indicative of a location of the portable device. The method also includes analyzing proximity information collected by the portable device indicative of when a person is near the portable device. The example method further includes generating presence information based on (1) the location information and (2) the proximity information, the presence information being indicative of whether the person is present in a media exposure environment associated with a media presentation device.

Abstract: Example methods, apparatus, systems and articles of manufacture to implement down-mixing compensation for audio watermarking are disclosed. Example watermark embedding methods disclosed herein include determining respective attenuation factors for a plurality of audio bands based on energy values associated with down-mixed audio samples corresponding to a first audio channel of a multi-channel audio signal and a second audio channel of the multi-channel audio signal. Disclosed example watermark embedding methods also include embedding a watermark in audio samples of the first audio channel based on the attenuation factors.

Abstract: Methods, apparatus, systems and articles of manufacture to count people in an audience are disclosed. An example method includes analyzing location information collected by a portable device indicative of a location of the portable device. The method also includes analyzing proximity information collected by the portable device indicative of when a person is near the portable device. The example method further includes generating presence information based on (1) the location information and (2) the proximity information, the presence information being indicative of whether the person is present in a media exposure environment associated with a media presentation device.

Abstract: Methods and apparatus to perform audio watermark detection and extraction are disclosed. An example method includes sampling a media signal to generate samples, wherein the media signal includes an embedded message, determining a first symbol value for a first block of the samples, determining a second symbol value for a second block of the samples, and determining, using a processor, a resulting symbol value, representative of a part of the embedded message, based on the first symbol value and the second symbol value for the first block of samples and the second block of samples, wherein the first block and the second block partially overlap.

Abstract: Methods and apparatus are disclosed for identifying media and, more particularly, to methods and apparatus for decoding identifiers after broadcast. An example method includes a portion of an identifying code from a media signal, determine a partition of the look-up table based on the portion of the identifying code wherein the partition of the look-up table includes reference signatures associated with the portion of the identifying code, and identify the media signal by comparing a signature extracted from the media signal to reference signatures in the partition of the look-up table.

Abstract: Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to embed information in generated acoustic signals are disclosed. Example methods disclosed herein to embed information in an acoustic signal output from an electric vehicle include obtaining a first audio signal to be used to generate the acoustic signal. Such example also include combining a second signal with the first audio signal, the second signal to convey first digital information that, when detected, indicates a presence of the electric vehicle. Such example methods further include providing the first audio signal with the second signal to an audio circuit that is to output the acoustic signal from the electric vehicle.

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 and apparatus for multi-purpose metering are disclosed. An example method includes determining whether a portable device is within a vicinity of a household monitoring system based on detecting an identifier via a first radio frequency (RF) signal, when the identifier from the first RF signal is associated with the portable device, determining whether a second acoustic signal includes the identifier associated with the portable device, deactivating a media detection circuit of the portable device when the identifier is detected via both the first RF signal and the second acoustic signal, and activating the media detection circuit of the portable device when the identifier is detected from the first RF signal and the second acoustic signal is absent.

Abstract: Example methods, apparatus, systems and articles of manufacture to implement down-mixing compensation for audio watermarking are disclosed. Example watermark embedding methods disclosed herein include determining respective attenuation factors for a plurality of audio bands based on energy values associated with down-mixed audio samples corresponding to a first audio channel of a multi-channel audio signal and a second audio channel of the multi-channel audio signal. Disclosed example watermark embedding methods also include embedding a watermark in audio samples of the first audio channel based on the attenuation factors.

Abstract: Methods and apparatus for multi-purpose metering are disclosed. An example method includes determining whether a portable device is within a vicinity of a household monitoring system based on detecting an identifier via a first radio frequency (RF) signal, when the identifier from the first RF signal is associated with the portable device, determining whether a second acoustic signal includes the identifier associated with the portable device, deactivating a media detection circuit of the portable device when the identifier is detected via both the first RF signal and the second acoustic signal, and activating the media detection circuit of the portable device when the identifier is detected from the first RF signal and the second acoustic signal is absent.

Abstract: Methods and apparatus for characterizing media are described. An example method includes converting at least a portion of a block of audio into a frequency domain representation, dividing the frequency domain representation into bands, determining a characteristic difference of a first band of the bands, and determining a signature bit based on the characteristic difference, wherein determining the signature bit is performed differently based on whether an index of the first band has a first property.

Abstract: Example methods, apparatus, systems and articles of manufacture to implement down-mixing compensation for audio watermarking are disclosed. Example methods disclosed herein to compensate for audio channel down-mixing when embedding watermarks in a multichannel audio signal include obtaining a watermark to be embedded in respective ones of a plurality of audio channels of the multichannel audio signal. Such example methods also include embedding the watermark in a first one of the plurality of audio channels based on a compensation factor that is to reduce perceptibility of the watermark when the first one of the plurality of audio channels is down-mixed with a second one of the plurality of audio channels after the watermark has been applied to the first and second ones of the plurality of audio channels.

Abstract: Methods, apparatus, systems and articles of manufacture to count people in an audience are disclosed. An example method includes analyzing location information collected by a portable device indicative of a location of the portable device. The method also includes analyzing proximity information collected by the portable device indicative of when a person is near the portable device. The example method further includes generating presence information based on (1) the location information and (2) the proximity information, the presence information being indicative of whether the person is present in a media exposure environment associated with a media presentation device.

Abstract: Methods and apparatus to present supplemental media on a second screen are disclosed. An example method includes establishing a connection between a digital media device and a computing device based on information identifying the computing device and, in response to establishing the connection, enabling the digital media device to skip a first type of media during a time-shifted presentation of media. The skipping is responsive to a command from a remote control device different than the computing device.

Abstract: Methods and apparatus for multi-purpose metering are disclosed. An example method includes transmitting a first discovery inquiry message in response to a wakeup timer expiration signal, disabling a media detection circuit of the portable device when a base unit responds to the discovery inquiry message, and enabling the media detection circuit of the portable device when the base unit response to the discovery inquiry message is absent.

Abstract: Methods and apparatus to present supplemental media on a second screen are disclosed. An example method includes obtaining, at a digital media device, media identifying data from audio data of a portion of first media being presented via the digital media device; determining that the portion of the first media is an advertisement based on the media identifying data; detecting, at the digital media device, a command to cause the digital media device to skip the portion of the first media; and providing an indication to a second device in response to detecting the command, the indication to cause the second device to present second media.

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 methods disclosed herein to detect media watermarks can include accessing multidimensional magnetic field data representative of values of a magnetic field measured within a first distance of audio circuitry that is to output an audio signal corresponding to media presented by a media device. Such example methods can also include processing the multidimensional magnetic field data to detect a watermark included in the audio signal.