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1. (WO2010074893) SURROUND SOUND VIRTUALIZER AND METHOD WITH DYNAMIC RANGE COMPRESSION
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

Claims

What is claimed is:

1. A surround sound virtualization method for producing output signals for reproduction by a pair of physical speakers at physical locations relative to a listener, where none of the physical locations is a location in a set of rear source locations, said method including the steps of:

(a) in response to input audio signals indicative of sound from the rear source locations, generating surround signals useful for driving the speakers at the physical locations to emit sound that the listener perceives as emitting from said rear source locations, including by performing dynamic range compression on the input audio signals; and

(b) generating the output signals in response to the surround signals and at least one other input audio signal, each said other input audio signal indicative of sound from a respective front source location, such that the output signals are useful for driving the speakers at the physical locations to emit sound that the listener perceives as emitting from the rear source locations and from each said front source location.

2. The method of claim 1, wherein the dynamic range compression is performed by nonlinear amplification of the input audio signals.

3. The method of claim 1, wherein step (a) includes a step of performing the dynamic range compression including by amplifying each of the input audio signals having a level below a predetermined threshold in a nonlinear manner depending on the amount by which the level is below the threshold.

4. The method of claim 3, wherein the level is an average level, over a time window, of said each of the input audio signals.

5. The method of claim 1, wherein the dynamic range compression provides improved localization of sound from the rear source locations, relative to sound from at least one said front source location, during reproduction of the output signals by the speakers at the physical locations.

6. The method of claim 1, wherein the physical speakers are front loudspeakers, the physical locations are in front of the listener, and step (a) includes the step of generating left and right surround signals in response to left and right rear input signals.

7. The method of claim 6, wherein step (b) includes the step of generating the output signals in response to the surround signals, and in response to a left input audio signal indicative of sound from a left front source location, a right input audio signal indicative of sound from a right front source location, and a center input audio signal indicative of sound from a center front source location.

8. The method of claim 7, wherein step (b) includes a step of generating a phantom center channel in response to the center input audio signal.

9. The method of claim 7, wherein the dynamic range compression provides improved localization of sound from the rear source locations, relative to sound from at least one said front source location, during reproduction of the output signals by the speakers at the physical locations.

10. The method of claim 7, wherein the dynamic range compression is performed by nonlinear amplification of the input audio signals.

11. The method of claim 7, wherein step (a) includes a step of performing the dynamic range compression including by amplifying each of the input audio signals having a level below a predetermined threshold in a nonlinear manner depending on the amount by which the level is below the threshold.

12. The method of claim 1, wherein step (a) includes a step of generating the surround signals including by transforming the input audio signals in accordance with a head-related transfer function.

13. The method of claim 12, wherein the input audio signals are a left rear input signal indicative of sound from a left rear source and a right rear input signal indicative of sound from a right rear source, and step (a) includes the steps of: transforming the left rear input signal in accordance with the head-related transfer function to generate a first virtualized audio signal indicative of sound from the left rear source as incident at a left ear of the listener and a second virtualized audio signal indicative of sound from the left rear source as incident at a right ear of the listener, and transforming the right rear input signal in accordance with the head-related transfer function to generate a third virtualized audio signal indicative of sound from the right rear source as incident at the left ear of the listener and a fourth virtualized audio signal indicative of sound from the right rear source as incident at the right ear of the listener.

14. The method of claim 1, wherein step (a) includes a step of generating the surround signals including by performing decorrelation on the input audio signals.

15. The method of claim 1, wherein step (a) includes a step of generating the surround signals including by performing cross-talk cancellation on the input audio signals.

16. The method of claim 1, wherein the physical loudspeakers are headphones and step (a) is performed without performing cross-talk cancellation on the input audio signals.

17. The method of claim 1, wherein step (a) includes the steps of: performing the dynamic range compression on the input audio signals to generate compressed audio signals; performing decorrelation on the compressed audio signals to generate decorrelated audio signals; transforming the decorrelated audio signals in accordance with a head-related transfer function to generate virtualized audio signals; and performing cross-talk cancellation on the virtualized audio signals to generate the surround signals.

18. A surround sound virtualization system configured to produce output signals for reproduction by a pair of physical speakers at physical locations relative to a listener, where none of the physical locations is a location in a set of rear source locations, including: a surround virtualizer subsystem, coupled and configured to generate surround signals in response to input audio signals including by performing dynamic range compression on the input audio signals, wherein the input audio signals are indicative of sound from the rear source locations, and the surround signals are useful for driving the speakers at the physical locations to emit sound that the listener perceives as emitting from said rear source locations; and a second subsystem, coupled and configured to generate the output signals in response to the surround signals and at least one other input audio signal, each said other input audio signal indicative of sound from a respective front source location, such that the output signals are useful for driving the speakers at the physical locations to emit sound that the listener perceives as emitting from the rear source locations and from each said front source location.

19. The system of claim 18, wherein the surround virtualizer subsystem is configured to perform the dynamic range compression by nonlinearly amplifying the input audio signals.

20. The system of claim 18, wherein the surround virtualizer subsystem is configured to perform the dynamic range compression including by amplifying each of the input audio signals having a level below a predetermined threshold in a nonlinear manner depending on the amount by which the level is below the threshold.

21. The system of claim 18, wherein said system is an audio digital signal processor, the surround virtualizer subsystem is coupled to receive the input audio signals, the second subsystem is coupled to the surround virtualizer subsystem to receive the surround signals, and the second subsystem is coupled to receive each said other input audio signal.

22. The system of claim 18, wherein the surround virtualizer subsystem is configured to perform the dynamic range compression such that said dynamic range compression provides improved localization of sound from the rear source locations, relative to sound from at least one said front source location, during reproduction of the output signals by the speakers at the physical locations.

23. The system of claim 18, wherein the physical speakers are front loudspeakers, the physical locations are in front of the listener, the input audio signals are left and right rear input signals, and the surround virtualizer subsystem is configured to generate left and right surround signals in response to the left and right rear input signals.

24. The system of claim 23, wherein the second subsystem is configured to generate the output signals in response to the surround signals, and in response to a left input audio signal indicative of sound from a left front source location, a right input audio signal indicative of sound from a right front source location, and a center input audio signal indicative of sound from a center front source location.

25. The system of claim 24, wherein the second subsystem is configured to generate a phantom center channel in response to the center input audio signal.

26. The system of claim 24, wherein the surround virtualizer subsystem is configured to perform the dynamic range compression so that said dynamic range compression provides improved localization of sound from the rear source locations, relative to sound from at least one said front source location, during reproduction of the output signals by the speakers at the physical locations.

27. The system of claim 24, wherein the surround virtualizer subsystem is configured to perform the dynamic range compression by nonlinearly amplifying the input audio signals.

28. The system of claim 24, wherein the surround virtualizer subsystem is configured to perform the dynamic range compression including by amplifying each of the input audio signals having a level below a predetermined threshold in a nonlinear manner depending on the amount by which the level is below the threshold.

29. The system of claim 18, wherein the surround virtualizer subsystem is configured to generate the surround signals including by transforming the input audio signals in accordance with a head-related transfer function.

30. The system of claim 18, wherein the surround virtualizer subsystem is configured to generate the surround signals including by performing decorrelation on the input audio signals.

31. The system of claim 18, wherein the surround virtualizer subsystem is configured to generate the surround signals including by performing cross-talk cancellation on the input audio si 'gbn' als.

32. The system of claim 18, wherein the physical speakers are headphones and the surround virtualizer subsystem is configured to generate the surround signals without performing cross-talk cancellation on the input audio signals

33. The system of claim 18, wherein the surround virtualizer subsystem includes: a compression stage coupled to receive the input audio signals and configured to perform the dynamic range compression on said input audio signals to generate compressed audio signals; a decorrelation stage coupled and configured to perform decorrelation on the compressed audio signals to generate decorrelated audio signals; a transform stage coupled and configured to transform the decorrelated audio signals in accordance with a head-related transfer function to generate virtualized audio signals; and a cross-talk cancellation stage coupled and configured to perform cross-talk cancellation on the virtualized audio signals to generate the surround signals.

34. The system of claim 33, wherein the input audio signals are a left rear input signal indicative of sound from a left rear source and a right rear input signal indicative of sound from a right rear source, the decorrelation stage is configured to generate a left decorrelated audio signal and a right decorrelated audio signal, the transform stage is configured to transform the left decorrelated audio signal in accordance with the head-related transfer function to generate a first virtualized audio signal indicative of sound from the left rear source as incident at a left ear of the listener and a second virtualized audio signal indicative of sound from the left rear source as incident at a right ear of the listener, and the transform stage is configured to transform the right decorrelated audio signal in accordance with the head-related transfer function to generate a third virtualized audio signal indicative of sound from the right rear source as incident at the left ear of the listener and a fourth virtualized audio signal indicative of sound from the right rear source as incident at the right ear of the listener.