Immersive audio rendering system

• US 9,154,897 B2
• Filed: 01/03/2012
• Issued: 10/06/2015
• Est. Priority Date: 01/04/2011
• Status: Active Grant

• Current Assignee: DTS, Inc. (Adeia Inc.)
• Original Assignee: DTS, Inc. (Adeia Inc.)
• Inventors: Kraemer, Alan D., Tracey, James, Katsianos, Themis
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): TON, DAVID L
• Application Number:
  US13/342,758
• Publication Number:
  US 20120170757A1
• Time in Patent Office: 1,372 Days
• Field of Search: 381/1, 381/17, 381/18, 381/310, 381/306, 381/307, 381/303
• US Class Current: 1/1
• CPC Class Codes: H04S 1/002 Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution control circuits for electronic adaptation of the sound field H04S7/30
• CPC Class Codes: H04S 2400/01 Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
• CPC Class Codes: H04S 2400/07 Generation or adaptation of the Low Frequency Effect [LFE] channel, e.g. distribution or signal processing
• CPC Class Codes: H04S 2400/11 Positioning of individual sound objects, e.g. moving airplane, within a sound field H04S2420/13 takes precedence
• CPC Class Codes: H04S 2420/01 Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
• CPC Class Codes: H04S 7/30 Control circuits for electronic adaptation of the sound field
• CPC Class Codes: H04S 7/302 Electronic adaptation of stereophonic sound system to listener position or orientation H04S7/301 takes precedence

Abstract

A depth processing system can employ stereo speakers to achieve immersive effects. The depth processing system can advantageously manipulate phase and/or amplitude information to render audio along a listener'"'"'s median plane, thereby rendering audio along varying depths. In one embodiment, the depth processing system analyzes left and right stereo input signals to infer depth, which may change over time. The depth processing system can then vary the phase and/or amplitude decorrelation between the audio signals over time to enhance the sense of depth already present in the audio signals, thereby creating an immersive depth effect.

Claims

1. A method of modulating a perspective enhancement applied to an audio signal, the method comprising:

receiving left and right audio signals, the left and right audio signals each comprising information about a spatial position of a sound source relative to a listener;

calculating difference information in the left and right audio signals;

applying at least one perspective filter to the difference information in the left and right audio signals to yield left and right output signals; and

applying a gain to the left and right output signals, a value of the gain based at least in part on the calculated difference information;

wherein at least said applying the gain is performed by one or more processors.

2. The method of claim 1, further comprising performing one or more of the following:

detecting an envelope of the difference information and smoothing the difference information.

3. The method of claim 2, wherein said modulating comprises modulating the application of the at least one perspective filter based at least in part on one or both of the envelope of the difference information and the smoothed difference information.

4. The method of claim 1, further comprising normalizing the difference information based at least in part on signal levels of the left and right audio signals.

5. The method of claim 4, wherein said modulating comprises modulating the application of the at least one perspective filter based at least in part on the normalized difference information.

6. The method of claim 4, wherein said normalizing comprises computing a geometric mean of the left and right audio signals and dividing the difference information with the computed geometric mean.

7. The method of claim 1, further comprising applying crosstalk cancellation to the left and right output signals to reduce backwave crosstalk.

8. The method of claim 1, further comprising applying a depth rendering enhancement to the left and right audio signals based at least in part on the difference information prior to applying the at least one perspective filter.

9. The method of claim 8, wherein said applying the depth rendering enhancement to the left and right audio signals comprises decorrelating the left and right audio signals.

10. A system for modulating a perspective enhancement applied to an audio signal, the system comprising:

a signal analysis component configured to analyze a plurality of audio signals by at least;

receiving left and right audio signals, the left and right audio signals each comprising information about a spatial position of a sound source relative to a listener, and

obtaining a difference signal from the left and right audio signals; and

a surround processor comprising one or more physical processors, the surround processor configured to apply at least one perspective filter to the difference signal to yield left and right output signals, wherein an output of the at least one perspective filter is modulated based at least in part on the difference signal.

11. The system of claim 10, wherein the signal analyzer is further configured to at least perform one or more of the following:

detecting an envelope of the difference signal and smoothing the difference signal.

12. The system of claim 11, wherein the surround processor is further configured to perform said modulation based at least in part on one or both of the envelope of the difference signal and the smoothed difference signal.

13. The system of claim 10, wherein the signal analyzer is further configured to normalize the difference signal based at least in part on signal levels of the left and right audio signals.

14. The system of claim 13, wherein the surround processor is further configured to perform said modulation based at least in part on the normalized difference signal.

15. The system of claim 13, wherein the signal analyzer is further configured to normalize the difference signal by at least computing a geometric mean of the left and right audio signals and dividing the difference signal with the computed geometric mean.

16. The system of claim 10, further comprising a crosstalk canceller configured to apply crosstalk cancellation to the left and right output signals.

17. The system of claim 10, further comprising a depth rendering component configured to render depth in the left and right audio signals based at least in part on the difference signal prior to applying the at least one perspective filter.

18. The system of claim 17, wherein said depth rendering component is further configured to render the depth by at least decorrelating the left and right audio signals.

19. Non-transitory physical computer storage comprising instructions stored therein configured to implement, in one or more processors, operations for modulating a perspective enhancement applied to an audio signal, the operations comprising:

receiving left and right audio signals, the left and right audio signals each comprising information about a spatial position of a sound source relative to a listener;

calculating difference information in the left and right audio signals;

applying at least one perspective filter to the difference information to yield left and right output signals; and

modulating said application of the at least one perspective filter based at least in part on the calculated difference information.

20. A system for modulating a perspective enhancement applied to an audio signal, the system comprising:

means for receiving left and right audio signals, the left and right audio signals each comprising information about a spatial position of a sound source relative to a listener;

means for calculating difference information in the left and right audio signals;

means for applying at least one perspective filter to the difference information to yield left and right output signals; and

means for modulating said application of the at least one perspective filter based at least in part on the calculated difference information.