Methods for phase ECU F0 interpolation split and related controller

1. A method for controlling a concealment method for a lost audio frame associated with a received audio signal, the method comprising:

obtaining at least one bin vector of a spectral representation for at least one tone, wherein the at least one bin vector includes three consecutive bin values for the at least one tone;

determining whether each of the three consecutive bin values has a complex value or a real value; and

responsive to the determination, processing the three consecutive bin values to estimate a frequency of the at least one tone based on whether each bin value has a complex value or a real value.

2. The method of claim 1 , wherein responsive to determining that each of the three consecutive bin values for the at least one tone has a complex value:

extracting a complex value coefficient for each of the three consecutive bin values;

calculating a fractional bin offset for the at least one tone based on the complex valued coefficient of each of the three consecutive bin values; and

calculating a bin frequency for the at least one tone based on the fractional bin offset.

3. The method of claim 2 , wherein calculating the fractional bin offset for the at least one tone comprises calculating the fractional bin offset for the at least one tone based a scaling coefficient, a window function used for the spectral representation, and a transform length for a frequency spectrum containing each of the three consecutive bin values for the at least one tone.

4. The method of claim 3 , wherein the scaling coefficient depends on a type of window function.

5. The method of claim 2 , wherein calculating the fractional bin offset for the at least one tone comprises calculating the fractional bin offset for the at least one tone based on a window function and a transform length for a frequency spectrum containing each of the three consecutive bin values.

6. The method of claim 5 , wherein calculating the fractional bin offset comprises calculating the fractional bin offset according to:

f k =+δ) C

wherein f k is the fractional bin offset for peak location k, δ is an interpolation value, and C is a coarse resolution in Hz/bin.

7. The method of claim 6 wherein δ is determined according to:

δ

=

K

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a

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b

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{

X

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X

k

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where K jacob is a scaling coefficient and X k−1 , X k , and X k+1 are complex-valued coefficients for the at least one tone at k.

8. The method of claim 1 , further comprising responsive to determining that at least one of the three consecutive bin values has a real value:

extracting a magnitude point for each of the three consecutive bin values;

calculating a fractional bin offset based on the magnitude points for each of the three consecutive bin values; and

calculating a bin frequency for the at least one tone based on the fractional bin offset.

9. The method of claim 1 , further comprising:

responsive to determining that each of the three consecutive bin values for the at least one tone has a complex value:

extracting a complex value coefficient for each of the three consecutive bin values;

calculating a fractional bin offset for the at least one tone based on the complex valued coefficient of each of the three consecutive bin values; and

calculating a bin frequency for the at least one tone based on the fractional bin offset;

responsive to determining that at least one of the three consecutive bin values has a real value:

extracting a magnitude point for each of the three consecutive bin values;

calculating the fractional bin offset for the at least one tone based on the magnitude point of each of the three consecutive bin values; and

calculating the bin frequency for the at least one tone based on the fractional bin offset.

10. The method of claim 1 , wherein determining and processing are performed for each of the at least one tone of the spectral representation.

11. An apparatus for controlling a concealment method for a lost audio frame associated with a received audio signal, the apparatus performing operations comprising:

obtaining at least one bin vector of a spectral representation for at least one tone, wherein the at least one bin vector includes three consecutive bin values for the at least one tone;

determining whether each of the three consecutive bin values has a complex value or a real value; and

responsive to the determination, processing the three consecutive bin values to estimate a frequency of the at least one tone based on whether each bin value has a complex value or a real value.

12. The apparatus of claim 11 wherein the apparatus comprises processing circuitry and memory coupled with the processing circuitry, wherein the memory includes instructions that when executed by the processing circuitry causes the apparatus to perform operations comprising responsive to determining that each of the three consecutive bin values for the at least one tone has a complex value:

extracting a complex value coefficient for each of the three consecutive bin values;

calculating a fractional bin offset for the at least one tone based on the complex valued coefficient of each of the three consecutive bin values; and

calculating a bin frequency for the at least one tone based on the fractional bin offset.

13. The apparatus according to claim 12 , wherein calculating the fractional bin offset for the at least one tone comprises calculating the fractional bin offset for the at least one tone based a scaling coefficient, a window function used for the spectral representation, and a transform length for a frequency spectrum containing each of the three consecutive bin values for the at least one tone.

14. The apparatus of claim 13 , wherein the scaling coefficient depends on a type of window function.

15. The apparatus of any of claim 12 , wherein calculating the fractional bin offset for the at least one tone comprises calculating the fractional bin offset for the at least one tone based on a window function and a transform length for a frequency spectrum containing each of the three consecutive bin values.

16. The apparatus of claim 15 , wherein calculating the fractional bin offset comprises calculating the fractional bin offset according to:

f k =( k +δ) C

wherein f k is the fractional bin offset for peak location k, δ is an interpolation value, and C is a coarse resolution in Hz/bin.

17. The apparatus of claim 16 wherein δ is determined according to:

δ

=

K

j

⁢

a

⁢

c

⁢

o

⁢

b

⁢

R

⁢

E

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{

X

k

-

1

-

X

k

+

1

2

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X

k

-

X

k

-

1

-

X

k

+

1

}

where K jacob is a scaling coefficient and X k−1 , X k , and X k+1 are complex-valued coefficients for the at least one tone at k.

18. The apparatus of claim 11 , wherein the apparatus comprises processing circuitry and memory coupled with the processing circuitry, wherein the memory includes instructions that when executed by the processing circuitry causes the apparatus to perform operations further comprising responsive to determining that at least one of the three consecutive bin values has a real value:

extracting a magnitude point for each of the three consecutive bin values;

calculating a fractional bin offset based on the magnitude points for each of the three consecutive bin values; and

calculating a bin frequency for the at least one tone based on the fractional bin offset.

19. The apparatus of claim 11 , wherein the apparatus comprises processing circuitry and memory coupled with the processing circuitry, wherein the memory includes instructions that when executed by the processing circuitry causes the apparatus to perform operations further comprising:

responsive to determining that each of the three consecutive bin values for the at least one tone has a complex value:

extracting a complex value coefficient for each of the three consecutive bin values;

calculating a fractional bin offset for the at least one tone based on the complex valued coefficient of each of the three consecutive bin values; and

calculating a bin frequency for the at least one tone based on the fractional bin offset;

responsive to determining that at least one of the three consecutive bin values has a real value:

extracting a magnitude point for each of the three consecutive bin values;

calculating the fractional bin offset for the at least one tone based on the magnitude point of each of the three consecutive bin values; and

calculating the bin frequency for the at least one tone based on the fractional bin offset.

20. The apparatus of claim 11 , wherein determining and processing are performed for each of the at least one tone of the spectral representation.

21. A decoder for controlling a concealment method for a lost audio frame associated with a received audio signal, wherein the decoder is adapted to perform operations comprising:

performing a sinusoidal analysis of a part of a previously decoded audio frame using windowing and a fast Fourier transform, FFT, to produce a spectral representation of the previously decoded audio frame;

identifying peaks of the spectral representation to identify a spectral representation for at least one tone;

obtaining at least one bin vector of the spectral representation for at least one tone, wherein the at least one bin vector includes three consecutive bin values for the at least one tone;

determining whether each of the three consecutive bin values has a complex value or a real value; and

responsive to the determination, processing the three consecutive bin values to estimate a frequency of the at least one tone based on whether each bin value has a complex value or a real value.

22. A computer program product comprising a non-transitory storage medium including program code to be executed by at least one processor of a decoder for controlling a concealment method for a lost audio frame associated with a received audio signal, whereby execution of the program code causes the decoder to perform operations comprising:

obtaining at least one bin vector of a spectral representation for at least one tone, wherein the at least one bin vector includes three consecutive bin values for the at least one tone;

determining whether each of the three consecutive bin values has a complex value or a real value; and

responsive to the determination, processing the three consecutive bin values to estimate a frequency of the at least one tone based on whether each bin value has a complex value or a real value.