Watermarking a Media Signal by Adjusting Frequency Domain Values and Adapting to the Media Signal

Abstract

A method of imperceptibly embedding a code signal in a media signal encodes auxiliary information in frequency components of the media signal. This method forms a code signal comprising a plurality of frequency components. The method embeds the code signal into the media signal by adjusting the frequency component relative to a neighboring component. The method changes selection of the plurality of frequency components corresponding to the codes signal for different instances of embedding the code signal in the media signal. The code signal may be used to encode a combination of fixed and variable message information in audio and image signals, including video. In one application, the attributes of the code signal are measured to determine broadcast signal quality. In another, the code signal robustly carries auxiliary information in distribution channels where distortion is common, such as compression, broadcast distortion, packet loss, digital to analog conversion, and ambient air transmission.

1 . A method of imperceptibly embedding a code signal in a media signal, the method comprising:
 forming a code signal comprising a plurality of frequency components;   embedding the code signal into the media signal, including for each of a plurality of frequency components, adjusting the frequency component relative to a neighboring component; and   changing selection of the plurality of frequency components corresponding to the codes signal for different instances of embedding the code signal in the media signal.   
     
     
         2 . The method of  claim 1  wherein the changing is computed as a function of the media signal. 
     
     
         3 . The method of  claim 2  wherein the function of the media signal comprises a hash of the media signal. 
     
     
         4 . The method of  claim 2  wherein the changing comprises including a first set of frequency components in the code signal that are repeated in the media signal, and a second set of frequency components that change as a function of the media signal. 
     
     
         5 . The method of  claim 1  wherein the code signal includes frequency components that are measured to determine broadcast signal quality. 
     
     
         6 . The method of  claim 1  wherein adjusting includes setting a frequency component to satisfy a predetermined relationship with a neighboring component. 
     
     
         7 . The method of  claim 1  wherein adjusting includes adjusting average energy of frequency components relative to a reference value. 
     
     
         8 . A computer readable medium on which is stored, which, when executed by a computer, performs a method of imperceptibly embedding a code signal in a media signal, the method comprising:
 forming a code signal comprising a plurality of frequency components;   embedding the code signal into the media signal, including for each of a plurality of frequency components, adjusting the frequency component relative to a neighboring component; and   changing selection of the plurality of frequency components corresponding to the codes signal for different instances of embedding the code signal in the media signal.