Methods and apparatus for characterizing media
View Patent ↗Methods and apparatus for characterizing media are described. A disclosed example apparatus includes a transformer, a decision metric processor, a signature determiner, and a processor to implement the transformer, the decision metric processor, and/or the signature determiner. The example transformer is to convert at least a portion of a block of audio into a frequency domain representation including a plurality of frequency components. The example decision metric processor is to: define a band of the frequency components; determine a difference in energy between a first convolution of a first complex vector with a first group of frequency bins in the band and a second convolution of a second complex vector with a second group of frequency bins in the band; and determine a decision metric for the band based on the difference. The example signature determiner is to determine a signature based on a value of the decision metric.
1. An apparatus, comprising:
a transformer to convert at least a portion of a block of audio into a frequency domain representation including a plurality of frequency components;
a decision metric processor to:
define a band of the frequency components;
determine a difference in energy between a first convolution of a first complex vector with a first group of frequency bins in the band and a second convolution of a second complex vector with a second group of frequency bins in the band; and
determine a decision metric for the band based on the difference;
a signature determiner to determine a signature based on a value of the decision metric; and
a processor to implement at least one of the transformer, the decision metric processor, or the signature determiner.
2. An apparatus as defined in claim 1 , wherein the first group of frequency bins comprises 3 frequency bins.
3. An apparatus as defined in claim 1 , wherein the decision metric processor is to:
define a second band of the frequency components;
compute a second difference in energy between a third convolution of a third complex vector with a third group of frequency bins in the second band and a fourth convolution of a fourth complex vector with a fourth group of frequency bins, the third complex vector being different than the first complex vector and the fourth complex vector being different than the second complex vector; and
determine the decision metric for the band based on the first and second differences.
4. An apparatus as defined in claim 1 , wherein the first convolution comprises a convolution between a complex vector and respective Fourier coefficients of the frequency bins in the first group.
5. An apparatus as defined in claim 1 , wherein the first and second complex vectors have constant energy.
6. An apparatus as defined in claim 1 , wherein the first complex vector has the form
[ a+jb,c,d+je],
where a, b, c, d, and e are constants.
7. An apparatus as defined in claim 1 , wherein the decision metric processor is to determine the difference in energy using the following equation:
D W1W2 [k]=|A W1 [k]| 2 −|A W2 [k]| 2 ,
where W 1 is the first complex vector, W 2 is the second complex vector, A W1 is a result of the first convolution, A W2 is a result of the second convolution, k is a frequency bin index, and D W1W2 [k] is a difference function for the index k, the first complex vector W 1 , and the second complex vector W 2 .
8. A method, comprising:
converting a portion of a block of audio into a frequency domain representation including a plurality of frequency components;
defining a band of the frequency components;
using a processor, determining a difference in energy between a first convolution of a first complex vector with a first group of frequency bins in the band and a second convolution of a second complex vector with a second group of frequency bins in the band;
using the processor, determining a decision metric for the band based on the difference; and
determining a signature based on a value of the decision metric.
9. A method as defined in claim 8 , wherein the first group of frequency bins comprises 3 frequency bins.
10. A method as defined in claim 8 , further comprising:
defining a second band of the frequency components;
computing a second difference in energy between a third convolution of a third complex vector with a third group of frequency bins in the second band and a fourth convolution of a fourth complex vector with a fourth group of frequency bins, the third complex vector being different than the first complex vector and the fourth complex vector being different than the second complex vector; and
determining the decision metric for the band based on the first and second differences.
11. A method as defined in claim 8 , wherein the first convolution comprises a convolution between a complex vector and respective Fourier coefficients of the frequency bins in the first group.
12. A method as defined in claim 8 , wherein the first and second complex vectors have constant energy.
13. A method as defined in claim 8 , wherein the first complex vector has the form
[ a+jb,c,d+je],
where a, b, c, d, and e are constants.
14. A method as defined in claim 8 , wherein determining the difference in energy comprises using the following equation:
D W1W2 [k]=|A W1 [k]| 2 −|A W2 [k]| 2 ,
where W 1 is the first complex vector, W 2 is the second complex vector, A W1 is a result of the first convolution, A W2 is a result of the second convolution, k is a frequency bin index, and D W1W2 [k] is a difference function for the index k, the first complex vector W 1 , and the second complex vector W 2 .
15. A tangible computer readable storage medium comprising computer readable instructions which, when executed, cause a processor to:
convert a portion of a block of audio into a frequency domain representation including a plurality of frequency components;
define a band of the frequency components;
determine a difference in energy between a first convolution of a first complex vector with a first group of frequency bins in the band and a second convolution of a second complex vector with a second group of frequency bins in the band;
determine a decision metric for the band based on the difference; and
determine a signature based on a value of the decision metric.
16. A storage medium as defined in claim 15 , wherein the instructions further cause the processor to:
define a second band of the frequency components;
compute a second difference in energy between a third convolution of a third complex vector with a third group of frequency bins in the second band and a fourth convolution of a fourth complex vector with a fourth group of frequency bins, the third complex vector being different than the first complex vector and the fourth complex vector being different than the second complex vector; and
determine the decision metric for the band based on the first and second differences.
17. A storage medium as defined in claim 15 , wherein the first convolution comprises a convolution between a complex vector and respective Fourier coefficients of the frequency bins in the first group.
18. A storage medium as defined in claim 15 , wherein the first and second complex vectors have constant energy.
19. A storage medium as defined in claim 15 , wherein the first complex vector has the form
[ a+jb,c,d+je],
where a, b, c, d, and e are constants.
20. A storage medium as defined in claim 15 , wherein determining the difference in energy comprises using the following equation:
D W1W2 [k]=|A W1 [k]| 2 −|A W2 [k]| 2 ,
where W 1 is the first complex vector, W 2 is the second complex vector, A W1 is a result of the first convolution, A W2 is a result of the second convolution, k is a frequency bin index, and D W1W2 [k] is a difference function for the index k, the first complex vector W 1 , and the second complex vector W 2 .