Systems and methods for generating haptic effects associated with an envelope in audio signals

1. A system for outputting haptic effects comprising:

a processor configured to:

receive an audio signal;

receive data associated with a haptic track;

synchronize the haptic track to the audio signal based in part on an envelope associated with the audio signal;

determine a haptic effect based in part on the audio signal and the haptic track;

store the haptic effect in the haptic track on a data store;

output a haptic signal associated with the haptic effect; and

output the audio signal to an audio output device configured to output an audible effect.

2. The system of claim 1 , wherein the haptic effect comprises one or more of: a variation in coefficient of friction, a simulated texture, or a vibration.

3. The system of claim 1 , wherein the processor is configured to determine the envelope by:

determining a Fast Fourier Transform of the audio signal within two or more time windows;

determining a magnitude for the Fast Fourier Transform for each time window;

determining a normalized signal by normalizing the magnitudes; and

determining positive values from the normalized signal.

4. The system of claim 3 , wherein the time windows are overlapping.

5. The system of claim 4 , wherein the envelope is the positive values of the normalized signal.

6. The system of claim 1 , wherein the processor is configured to determine the envelope by:

determining a power spectral density of the audio signal within two or more time windows;

determining a sum signal by summing the power spectral density values for each time window;

sampling the sum signal to determine a sample signal; and

interpolating and normalizing the sample signal.

7. A method for outputting haptic effects comprising:

receiving an audio signal;

receiving data associated with a haptic track;

synchronizing the haptic track to the audio signal based in part on an envelope associated with the audio signal;

determining a haptic effect based in part on the audio signal and the haptic track;

storing the haptic effect in the haptic track on a data store;

outputting a haptic signal associated with the haptic effect; and

outputting the audio signal to an audio output device configured to output an audible effect.

8. The method of claim 7 , wherein the haptic effect comprises one or more of: a variation in coefficient of friction, a simulated texture, or a vibration.

9. The method of claim 7 , wherein the envelope associated with the audio signal comprises a signal determined by:

determining a Fast Fourier Transform of the audio signal within two or more time windows;

determining a magnitude for the Fast Fourier Transform for each time window;

determining a normalized signal by normalizing the magnitudes; and

determining positive values from the normalized signal.

10. The method of claim 9 , wherein the time windows are overlapping.

11. The method of claim 9 , wherein the envelope is the positive values of the normalized.

12. The method of claim 7 , wherein the envelope associated with the audio signal comprises a signal determined by:

determining a power spectral density of the audio signal within two or more time windows;

determining a sum signal by summing the power spectral density values for each time window;

sampling the sum signal to determine a sample signal; and

interpolating and normalizing the sample signal.

13. The method of claim 12 , wherein the envelope is the interpolated and normalized sample signal.

14. The method of claim 7 , further comprising filtering the envelope.

15. The method of claim 14 , wherein filtering the envelope signal comprises one or more of: filtering the envelope signal using a threshold and filtering the envelope using a level of haptic silence.

16. A non-transitory computer readable medium comprising program code, which when executed by a processor, is configured to cause the processor to:

receive an audio signal;

receive data associated with a haptic track;

synchronize the haptic track to the audio signal based in part on an envelope associated with the audio signal;

determine a haptic effect based in part on the audio signal and the haptic track;

store the haptic effect in the haptic track on a data store;

output a haptic signal associated with the haptic effect; and

output the audio signal to an audio output device configured to output an audible effect.

17. The non-transitory computer readable medium of claim 16 , wherein the haptic effect comprises one or more of: a variation in coefficient of friction, a simulated texture, or a vibration.

18. The non-transitory computer readable medium of claim 16 , wherein the envelope associated with the audio signal comprises a signal determined by:

determining a Fast Fourier Transform of the audio signal within two or more time windows;

determining a magnitude for the Fast Fourier Transform for each time window;

determining a normalized signal by normalizing the magnitudes; and

determining positive values from the normalized signal.

19. The non-transitory computer readable medium of claim 18 , wherein the time windows are overlapping.

20. The non-transitory computer readable medium of claim 18 , wherein the envelope is the positive values of the normalized signal.