Scaled Window Overlap Add for Mixed Signals

• US 20080033584A1
• Filed: 04/13/2007
• Published: 02/07/2008
• Est. Priority Date: 08/03/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Chen, Juin-Hwey, Zopf, Robert W.
• Granted Patent: US 8,731,913 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm

Abstract

A method for overlap-adding signals useful for performing frame loss concealment (FLC) in an audio decoder as well as in other applications. The method uses a dynamic mix of windows to overlap two signals whose normalized cross-correlation may vary from zero to one. If the overlapping signals are decomposed into a correlated component and an uncorrelated component, they are overlap-added separately using the appropriate window, and then added together. If the overlapping signals are not decomposed, a weighted mix of windows is used. The mix is determined by a measure estimating the amount of cross-correlation between overlapping signals, or the relative amount of correlated to uncorrelated signals.

Claims

1. A method for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

adding a correlated component of the first segment to a correlated component of the second segment to generate a combined correlated component;

adding an uncorrelated component of the first segment to an uncorrelated component of the second segment to generate a combined uncorrelated component; and

adding the combined correlated component to the combined uncorrelated component to generate an overlapped signal.

2. The method of claim 1, wherein adding a correlated component of the first segment to a correlated component of the second segment comprises:

multiplying the correlated component of the first segment by a correlated fade-out window to generate a first product;

multiplying the correlated component of the second segment by a correlated fade-in window to generate a second product; and

adding the first product to the second product to generate the combined correlated component.

3. The method of claim 1, wherein adding an uncorrelated portion of the first segment to an uncorrelated portion of the second segment comprises:

multiplying the uncorrelated component of the first segment by an uncorrelated fade-out window to generate a first product;

multiplying the uncorrelated component of the second segment by an uncorrelated fade-in window to generate a second product; and

adding the first product to the second product to generate the combined uncorrelated component.

4. A method for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

multiplying the first segment by an estimate β

of the correlation between the first segment and the second segment to generate a first product;

adding the first product to a correlated component of the second segment to generate a combined correlated component;

multiplying the first segment by (1−

β

) to generate a second product;

adding the second product to an uncorrelated component of the second segment to generate a combined uncorrelated component; and

adding the combined correlated component to the combined uncorrelated component to generate an overlapped signal.

5. The method of claim 4, wherein multiplying the first segment by an estimate β

of the correlation between the first segment and the second segment to generate a first product comprises;

multiplying the first segment by a correlated fade-out window to generate a third product; and

multiplying the third product by β

.

6. The method of claim 5, wherein adding the first product to a correlated component of the second segment to generate a combined correlated component comprises:

multiplying the correlated component of the second segment by a correlated fade-in window to generate a fourth product; and

adding the first product to the fourth product.

7. The method of claim 4, wherein multiplying the first segment by (1−

β

) to generate a second product comprises;

multiplying the first segment by an uncorrelated fade-out window to generate a third product; and

multiplying the third product by (1−

β

).

8. The method of claim 7, wherein adding the second product to an uncorrelated component of the second segment to generate a combined uncorrelated component comprises:

multiplying the uncorrelated component of the second segment by an uncorrelated fade-in window to generate a fourth product; and

adding the second product to the fourth product.

9. A method for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

multiplying the second segment by an estimate β

of the correlation between the first segment and the second segment to generate a first product;

adding the first product to a correlated component of the first segment to generate a combined correlated component;

multiplying the second segment by (1−

β

) to generate a second product;

adding the second product to an uncorrelated component of the first segment to generate a combined uncorrelated component; and

adding the combined correlated component to the combined uncorrelated component to generate an overlapped signal.

10. The method of claim 9, wherein multiplying the second segment by an estimate β

of the correlation between the first segment and the second segment to generate a first product comprises;

multiplying the second segment by a correlated fade-in window to generate a third product; and

multiplying the third product by β

.

11. The method of claim 10, wherein adding the first product to a correlated component of the first segment to generate a combined correlated component comprises:

multiplying the correlated component of the first segment by a correlated fade-out window to generate a fourth product; and

adding the first product to the fourth product.

12. The method of claim 9, wherein multiplying the second segment by (1−

β

) to generate a second product comprises;

multiplying the second segment by an uncorrelated fade-in window to generate a third product; and

multiplying the third product by (1−

β

).

13. The method of claim 12, wherein adding the second product to an uncorrelated component of the first segment to generate a combined uncorrelated component comprises:

multiplying the uncorrelated component of the first segment by an uncorrelated fade-out window to generate a fourth product; and

adding the second product to the fourth product.

14. A method for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

adding the first segment to the second segment to generate a first combined component;

multiplying the first combined component by an estimate β

of the correlation between the first segment and the second segment to generate a first product;

adding the first segment to the second segment to generate a second combined component;

multiplying the second combined component by (1−

β

) to generate a second product; and

adding the first product to the second product to generate an overlapped signal.

15. The method of claim 14, wherein adding the first segment to the second segment to generate a first combined component comprises:

multiplying the first segment by a correlated fade-out window to generate a third product;

multiplying the second segment by a correlated fade-in window to generate a fourth product; and

adding the third product to the fourth product to generate the first combined component.

16. The method of claim 14, wherein adding the first segment to the second segment to generate a second combined component comprises:

multiplying the first segment by an uncorrelated fade-out window to generate a third product;

multiplying the second segment by an uncorrelated fade-in window to generate a fourth product; and

adding the third product to the fourth product to generate the second combined component.

17. A system for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

a first multiplier configured to multiply a correlated component of the first segment by a correlated fade-out window to generate a first product;

a second multiplier configured to multiply a correlated component of the second segment by a correlated fade-in window to generate a second product;

a first adder configured to add the first product to the second product to generate the combined correlated component;

a third multiplier configured to multiply an uncorrelated component of the first segment by an uncorrelated fade-out window to generate a third product;

a fourth multiplier configured to multiply an uncorrelated component of the second segment by an uncorrelated fade-in window to generate a fourth product;

a second adder configured to add the third product to the fourth product to generate the combined uncorrelated component; and

a third adder configured to add the combined correlated component to the combined uncorrelated component to generate an overlapped signal.

18. A system for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

a first multiplier configured to multiply the first segment by a correlated fade-out window to generate a first product;

a second multiplier configured to multiply the first product by β

;

to generate a second product;

a third multiplier configured to multiply a correlated component of the second segment by a correlated fade-in window to generate a third product;

a first adder configured to add the second product to the third product to generate a combined correlated component;

a fourth multiplier configured to multiply the first segment by an uncorrelated fade-out window to generate a fourth product;

a fifth multiplier configured to multiply the fourth product by (1−

β

) to generate a fifth product;

a sixth multiplier configured to multiply an uncorrelated component of the second segment by an uncorrelated fade-in window to generate a sixth product;

a second adder configured to add the fifth product to the sixth product to generate a combined uncorrelated component; and

a third adder configured to add the combined correlated component to the combined uncorrelated component to generate an overlapped signal.

19. A system for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

a first multiplier configured to multiply the second segment by a correlated fade-in window to generate a first product;

a second multiplier configured to multiply the first product by an estimate β

of the correlation between the first segment and the second segment to generate a second product;

a third multiplier configured to multiply a correlated component of the first segment by a correlated fade-out window to generate a third product;

a first adder configured to add the second product to the third product to generate a combined correlated component;

a fourth multiplier configured to multiply the second segment by an uncorrelated fade-in window to generate a fourth product;

a fifth multiplier configured to multiply the fourth product by (1−

β

) to generate a fifth product;

a sixth multiplier configured to multiply an uncorrelated component of the first segment by an uncorrelated fade-out window to generate a sixth product;

a second adder configured to add the fifth product to the sixth product to generate a combined uncorrelated component; and

a third adder configured to add the combined correlated component to the combined uncorrelated component to generate an overlapped signal.

20. A system for performing an overlap-add operation for transitioning from a first segment of an audio signal to a second segment of the audio signal, comprising:

a first multiplier configured to multiply the first segment by a correlated fade-out window to generate a first product;

a second multiplier configured to multiply the second segment by a correlated fade-in window to generate a second product;

a first adder configured to add the first product to the second product to generate a first combined component;

a third multiplier configured to multiply the first combined component by an estimate β

of the correlation between the first segment and the second segment to generate a third product;

a fourth multiplier configured to multiply the first segment by an uncorrelated fade-out window to generate a fourth product;

a fifth multiplier configured to multiply the second segment by an uncorrelated fade-in window to generate a fifth product;

a second adder configured to add the fourth product to the fifth product to generate a second combined component;

a sixth multiplier configured to multiply the second combined component by (1−

β

) to generate a sixth product; and

a third adder configured to add the fifth product to the sixth product to generate an overlapped signal.