Human auditory system modeling with masking energy adaptation

1. A method of saturation handling for audio watermarking of an audio signal, the method comprising:

applying a perceptual model to the audio signal to produce masking thresholds for inserting a digital data signal;

adapting the digital data signal according to the masking thresholds;

identifying a location within the audio signal where insertion of the digital data signal exceeds a clipping limit; and

applying a clipping function to smooth a change made to insert the digital data signal around the location;

further comprising:

using a programmed processor, performing the acts of:

transforming a block of samples of the audio signal into a frequency spectrum comprising frequency components;

from the frequency spectrum, deriving group masking energies, the group masking energies each corresponding to a group of neighboring frequency components in the frequency spectrum; and

for each of plural groups of neighboring frequency components, allocating the group masking energy to the frequency components in a corresponding group in proportion to energy of the frequency components within the corresponding group to provide adapted mask energies for the frequency components within the corresponding group, the adapted mask energies providing masking thresholds for the perceptual model of the audio signal;

for each of plural groups of neighboring frequency components, determining a variance and a group average of the energies of the frequency components within a group;

in a group where variance exceeds a threshold, comparing the adapted mask energies of frequency components with group average; and

for frequency components in the group with adapted mask energy that exceeds the group average, setting the group average as a masking threshold for the frequency component.

2. A non-transitory computer readable medium on which is stored instructions, which when executed by a processor, perform a method of:

transforming a block of samples of an audio signal into a frequency spectrum comprising frequency components;

from the frequency spectrum, deriving group masking energies, the group masking energies each corresponding to a band of frequency components in the frequency spectrum;

for each of plural bands of frequency components, allocating the group masking energy to the frequency components in a corresponding band in proportion to energy of the frequency components within the corresponding band to provide adapted mask energies for the frequency components within the corresponding band, the adapted mask energies providing masking thresholds for a perceptual model of the audio signal;

adapting a digital data signal according to the masking thresholds;

identifying a location within the audio signal where insertion of the digital data signal exceeds a clipping limit; and

applying a clipping function to smooth a change made to insert the digital data signal around the location.

3. A electronic device comprising:

an audio sensor;

a memory;

a processor coupled to the memory, the processor configured to execute instructions stored in the memory to:

convert a block of samples of an audio signal obtained from the audio sensor into a frequency spectrum comprising frequency components;

compute group masking energies from the frequency spectrum, the group masking energies each corresponding to a group of neighboring frequency components in the frequency spectrum;

allocate the group masking energy to the frequency components in a corresponding group in proportion to energy of the frequency components within the corresponding group to provide adapted mask energies for the frequency components within the corresponding group, the adapted mask energies providing masking thresholds for a psychoacoustic model of the audio signal;

adapt a digital data signal according to the masking thresholds;

identify a location within the audio signal where insertion of the digital data signal exceeds a clipping limit; and

apply a clipping function to smooth a change made to insert the digital data signal around the location.

4. A method of saturation handling for audio watermarking of an audio signal, the method comprising:

transforming a block of samples of the audio signal into a frequency spectrum comprising frequency components;

from the frequency spectrum, deriving group masking energies, the group masking energies each corresponding to a group of neighboring frequency components in the frequency spectrum; and

for each of plural groups of neighboring frequency components, allocating the group masking energy to the frequency components in a corresponding group in proportion to energy of the frequency components within the corresponding group to provide adapted mask energies for the frequency components within the corresponding group, the adapted mask energies providing masking thresholds for a perceptual model of the audio signal;

applying the perceptual model to the audio signal to produce masking thresholds for inserting a digital data signal;

adapting a digital data signal according to the masking thresholds;

identifying a location within the audio signal where insertion of the digital data signal exceeds a clipping limit; and

applying a clipping function to smooth a change made to insert the digital data signal around the location.

5. The method of claim 4 wherein the groups of neighboring frequency components correspond to partitions of the frequency spectrum and group masking energies comprise partition masking thresholds;

the method further comprising:

determining partition energy from the energy of frequency components in a partition;

for each of plural partitions, determining a masking effect of a masker partition on neighboring maskee partitions by applying a spreading function to partition energy of the masker partition; and

from the masking effects of plural masker partitions on a maskee partition, determining a combined masking effect on the maskee partition, the combined masking effect providing the group masking energy of the maskee partition.

6. The method of claim 4 wherein deriving group masking energies comprises decimating frequency components within a group of neighboring frequency components and obtaining the group masking energy from one or more frequency components after the decimating.

7. The method of claim 4 wherein the masking thresholds are derived for short audio blocks of the audio signal at a first frequency resolution and interpolated for a long audio block of the audio signal at a second frequency resolution, higher than the first frequency resolution; the method further comprising:

applying interpolated masking thresholds to the auxiliary data signal,

controlling audibility of encoding the digital data signal into the audio signal with the masking thresholds by applying the masking thresholds to control changes in the audio signal due to the encoding of the digital data signal.

8. The method of claim 4 wherein the clipping function comprises a window function.

9. The method of claim 8 wherein the window function comprise a Gaussian shaped window function.