Audio processing with time advanced inserted payload signal

Abstract

An audio processing apparatus for modifying a primary audio signal includes a modulator that increases or decreases a level of a noise signal generated by a noise generator, in response to an increase or a decrease of a detected signal level of the primary audio signal, to generate a modulated noise signal. The apparatus further includes a combiner that combines the primary audio signal and the modulated noise signal. The modulator operates, with respect to a signal delayer, to time-advance a decrease in the level of said noise signal based on a corresponding decrease in the signal level of the primary audio signal.

1 . An audio processing apparatus for modifying a primary audio signal, said apparatus comprising:
 a modulator that increases or decreases a level of a noise signal generated by a noise generator, in response to an increase or a decrease of a detected signal level of said primary audio signal, to generate a modulated noise signal; and   a combiner that combines said primary audio signal and said modulated noise signal,   wherein said modulator operates, with respect to a signal delayer, to time-advance a decrease in said level of said noise signal based on a corresponding decrease in said signal level of said primary audio signal.   
     
     
         2 . The audio processing apparatus according to  claim 1 , in which said modulator operates, with respect to said signal delayer, such that an increase in said level of said noise signal is not time-advanced with respect to a corresponding increase in said signal level of said primary audio signal. 
     
     
         3 . The audio processing apparatus according to  claim 1 , in which said combiner adds said noise signal to said primary audio signal. 
     
     
         4 . The audio processing apparatus according to  claim 1 , further comprising:
 a plurality of sets, each of the plurality sets including said level detector, said modulator and said combiner, each of the plurality of sets operating one of two or more audio frequency bands; and   means for combining outputs from said combiners in each of the plurality of sets.   
     
     
         5 . The audio processing apparatus according to  claim 1 , further comprising:
 a payload generator that generates said payload signal based on at least one of a serial number, a location identifier, and a location private key,   wherein the location private key is used to encrypt the location identifier.   
     
     
         6 . The audio processing apparatus according to  claim 1 , in which a plurality of encryption keys seed said noise generator. 
     
     
         7 . The audio processing apparatus according to  claim 1 , in which said noise signal is time-advanced to terminate decreasing immediately prior to or at the same time as terminating the corresponding decrease in said signal level of said primary audio signal. 
     
     
         8 . The audio processing apparatus according to  claim 1 , in which said noise signal is time-advanced to terminate decreasing immediately after terminating the corresponding decrease in said signal level of said primary audio signal. 
     
     
         9 . The audio processing apparatus according to  claim 1 , in which said noise generator is a pseudo-random noise generator seeded by all of a payload signal. 
     
     
         10 . The audio processing apparatus according to  claim 9 , in which said noise generator encrypts said payload data in accordance with a security key. 
     
     
         11 . The audio processing apparatus according to  claim 9 , in which said payload signal is a forensic marking signal. 
     
     
         12 . The audio processing apparatus according to  claim 9 , wherein a first layer of said noise signal generated by said noise generator is seeded by a first subset of said payload signal. 
     
     
         13 . The audio processing apparatus according to  claim 12 , wherein a second layer of said noise signal generated by said noise generator is seeded by a second subset of said payload signal, said second subset including all of said first subset. 
     
     
         14 . The audio processing apparatus according to  claim 13 , wherein an nth layer of said noise signal generated by said noise generator is seeded by all of said payload signal including said first subset and said second subset. 
     
     
         15 . The audio processing apparatus according to  claim 1 , wherein said primary audio signal is divided in a plurality of frequency bands spread throughout a logarithmic frequency scale. 
     
     
         16 . The audio processing apparatus according to  claim 15 , wherein each of said plurality of frequency bands is then processed separately to generate a gain envelope that is used to modulate an amplitude of a corresponding frequency band in said noise signal. 
     
     
         17 . The audio processing apparatus according to  claim 1 , wherein said primary audio signal is divided in a plurality of frequency bands based on an octave scale. 
     
     
         18 . The audio processing apparatus according to  claim 11 , in which said forensic marking signal includes at least one of a fingerprint and a watermark. 
     
     
         19 . An audio processing method for modifying a primary audio signal, said method comprising:
 modulating by increasing or decreasing a level of a noise signal generated by a noise generator, in response to an increase or a decrease of a detected signal level of said primary audio signal, to generate a modulated noise signal; and   combining said primary audio signal and said modulated noise signal,   wherein in said modulating, a decrease in said level of said noise signal is time-advanced, with respect to a signal delayer, based on a corresponding decrease in said signal level of said primary audio signal.   
     
     
         20 . A non-transitory computer-readable storage medium having computer readable program codes embodied in the computer readable storage medium that, when executed cause a computer to execute:
 modulating by increasing or decreasing a level of a noise signal generated by a noise generator, in response to an increase or a decrease of a detected signal level of said primary audio signal, to generate a modulated noise signal; and   combining said primary audio signal and said modulated noise signal,   wherein in said modulating, a decrease in said level of said noise signal is time-advanced, with respect to a signal delayer, based on a corresponding decrease in said signal level of said primary audio signal.