Audio signal decoder and method for producing a scaled reconstructed audio signal

1. An apparatus that decodes a multiple channel audio signal, comprising:

a decoder that receives a coded audio signal, a coded balance factor and a coded gain value;

a gain vector decoder of an enhancement layer decoder that generates a decoded gain value from the coded gain value;

a scaling unit of the enhancement layer decoder that scales the coded audio signal with the decoded gain value to generate a scaled audio signal;

a signal combiner that applies the coded balance factor to the scaled audio signal to generate a decoded multiple channel audio signal and outputs the decoded multiple channel audio signal.

2. The apparatus of claim 1 , wherein the gain value is a gain matrix.

3. The apparatus of claim 2 , wherein the gain matrix is at least one of frequency selective and dependent on the coded audio signal.

4. The apparatus of claim 1 , wherein the coded audio signal is one of a mono and a multiple channel signal.

5. The apparatus of claim 4 , wherein the coded multiple channel audio signal is a stereo signal.

6. The apparatus of claim 1 , wherein the gain vector decoder receives a reconstructed audio vector Ŝ and an index representative of a gain vector and wherein the gain vector decoder further comprises:

a gain selector of the gain vector decoder that detects a set of peaks in the reconstructed audio vector, generates a scaling mask ψ(Ŝ) based on the detected set of peaks, and generates the gain vector g* based on at least the scaling mask and the index representative of the gain vector; and

a scaling unit of the gain vector decoder that scales the reconstructed audio vector with the gain vector to produce a scaled reconstructed audio signal.

7. The apparatus of claim 6 , further comprising:

an error signal decoder that generates an enhancement to the reconstructed audio vector; and

a signal combiner of the enhancement layer decoder that combines the scaled reconstructed audio signal and the enhancement to the reconstructed audio vector to generate an enhanced decoded signal.

8. A method for decoding a multiple channel audio signal, comprising:

receiving a coded audio signal, a coded balance factor and a coded gain value;

generating a decoded gain value from the coded gain value;

scaling the coded audio signal with the decoded gain value to generate a scaled audio signal;

applying the coded balance factor to the scaled audio signal to generate a decoded multiple channel audio signal; and

outputting the decoded multiple channel audio signal.

9. The method of claim 8 , the method comprising:

receiving a reconstructed audio vector Ŝ and an index representative of a gain vector;

detecting a set of peaks in the reconstructed audio vector;

generating a scaling mask ψ(Ŝ) based on the detected set of peaks;

generating the gain vector g* based on at least the scaling mask and the index representative of the gain vector; and

scaling the reconstructed audio vector with the gain vector to produce a scaled reconstructed audio signal.

10. A method for coding a multiple channel audio signal, comprising:

receiving a multiple channel audio signal that comprises a plurality of audio signals;

coding the multiple channel audio signal to generate a coded audio signal;

scaling the coded audio signal with a plurality of gain values to generate a plurality of candidate coded audio signals, wherein at least one of the candidate coded audio signals is scaled;

generating a balance factor having a plurality of balance factor components each associated with an audio signal of the plurality of audio signals of the multiple channel audio signal;

generating an estimate of the multiple channel audio signal based on the balance factor and the at least one scaled coded audio signal of the plurality of candidate coded audio signals;

evaluating a distortion value based on the estimate of the multiple channel audio signal and the multiple channel audio signal to determine a representation of an optimal gain value of the plurality of gain values;

outputting for at least one of transmission and storage the representation of the optimal gain value.

11. The method of claim 10 , wherein a gain value of the plurality of gain values is a gain matrix with vector g j as the diagonal component.

12. The method of claim 11 , wherein the gain matrix is frequency selective.

13. The method of claim 10 , wherein the representation of the optimal gain value is given by:

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14. The method of claim 10 , wherein each balance factor component is given by:

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15. The method of claim 10 , wherein generating the balance factor comprises:

generating a correlation value between the scaled coded audio signal and at least one of the audio signals of the multiple channel audio signal.

16. The method of claim 10 , wherein generating the balance factor comprises:

generating a self correlation between at least one of the audio signals of the multiple channel audio signal; and

generating a square root of the self correlation.

17. The method of claim 16 , further comprising:

choosing a gain value from a plurality of gain values to scale the coded audio signal and generate the scaled coded audio signals.

18. The method of claim 10 , further comprising:

generating a distortion value based on the estimate of the multiple channel audio signal and the multiple channel audio signal.

19. The method of claim 18 , wherein the gain value is based upon the distortion value.

20. The method of claim 19 , wherein the distortion value comprises a plurality of distortion values corresponding to the plurality of estimates.