Methods and apparatus to audio watermarking and watermark detection and extracted are described herein. According to an example method, an identifier is encoded in media content when a different identifier has been previously encoded. According to another example method, messages decoded from media content are validated to provide improved decoding accuracy. In another example method, decoded symbols are stored in memory and synchronization symbols are located to detect a message encoded in media content.

Methods, systems, and apparatuses for presence detection are described herein. A first computing device may emit an inaudible audio signal. A second computing device may detect the inaudible audio signal. The second computing device may send an indication of detecting the inaudible audio signal. The first computing device may cause presentation of content to be modified based on the indication sent by the second computing device and a user profile associated with a user of the second computing device.

Methods, systems, and apparatuses for presence detection are described herein. A first computing device may emit an inaudible audio signal. A second computing device may detect the inaudible audio signal. The second computing device may send an indication of detecting the inaudible audio signal. The first computing device may cause presentation of content to be modified based on the indication sent by the second computing device and a user profile associated with a user of the second computing device.

Encoding and decoding methods and apparatus are described. An example method is described for embedding information into audio by determining a first set of frequency components to represent a synchronization block, the synchronization block representing one of a plurality of different message types, one frequency component from each set of frequency components being located in a respective code band, and spacing between adjacent code bands is equal to or less than the spacing between adjacent frequency components of each code band. Determining amplitudes of respective ones of the first set of frequency components representing the synchronization block based on a masking ability of an audio block of the audio. Synthesizing the first set of frequency components representing the synchronization block to determine a first set of synthesized code frequency components, based on the determined amplitudes. Combining the first set of synthesized code frequency components with the audio block.

A broadcast receiving apparatus includes: a tuner configured to receive a transmission wave in which identification information is stored in a carrier, the carrier being modulated differently from a data carrier, a frequency band when the transmission wave is transmitted in an air being able to be identified by the identification information; and a controller. The controller is configured to identify a frequency band when the transmission wave is transmitted in the air by using the identification information contained in transmission wave received by the tuner.

A broadcast receiving apparatus includes: a tuner configured to receive a transmission wave in which identification information is stored in a carrier, the carrier being modulated differently from a data carrier, a frequency band when the transmission wave is transmitted in an air being able to be identified by the identification information; and a controller. The controller is configured to identify a frequency band when the transmission wave is transmitted in the air by using the identification information contained in transmission wave received by the tuner.

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.

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.

A broadcast receiving apparatus includes: a tuner configured to receive a transmission wave in which identification information is stored in a carrier, the carrier being modulated differently from a data carrier, a frequency band when the transmission wave is transmitted in an air being able to be identified by the identification information; and a controller. The controller is configured to identify a frequency band when the transmission wave is transmitted in the air by using the identification information contained in transmission wave received by the tuner.

A broadcast receiving apparatus includes: a tuner configured to receive a transmission wave in which identification information is stored in a carrier, the carrier being modulated differently from a data carrier, a frequency band when the transmission wave is transmitted in an air being able to be identified by the identification information; and a controller. The controller is configured to identify a frequency band when the transmission wave is transmitted in the air by using the identification information contained in transmission wave received by the tuner.