Encoding of multiple audio signals

Patent metadata

Field	Value
Publication number	US-10586544-B2
Application number	US-201816152357-A
Country	US
Kind code	B2
Filing date	Oct 4, 2018
Priority date	Nov 20, 2015
Publication date	Mar 10, 2020
Grant date	Mar 10, 2020

Abstract

A device includes an encoder configured to determine, during a first period, that a first audio signal is a leading signal and that a second audio signal is a lagging signal. The encoder is also configured to generate a first frame of at least one encoded signal based on a first modified version of the second audio signal that is generated by adjusting the second audio signal based on a first mismatch value. The encoder is configured to determine, during a second period, that the first audio signal is the leading signal and that the second audio signal is the lagging signal. The encoder is configured to generate a second frame of the at least one encoded signal based on a second modified version of the second audio signal that is generated by adjusting the second audio signal based on the first mismatch value and a second mismatch value.

First claim

What is claimed is:

1. A device comprising:
an encoder configured to:
determine, during a first period, a first mismatch value indicative of an amount of temporal mismatch between a first audio signal and a second audio signal;
determine, based on the first mismatch value, that the first audio signal is a leading audio signal and that the second audio signal is a lagging audio signal;
generate a first frame of at least one encoded signal based on the first audio signal and a first modified version of the second audio signal, the first modified version of the second audio signal generated by adjusting the second audio signal based on the first mismatch value;
determine, during a second period subsequent to the first period and based on a second mismatch value, that the first audio signal is the leading audio signal and that the second audio signal is the lagging audio signal; and
in response to determining, during each of the first period and the second period, that the first audio signal is the leading audio signal and that the second audio signal is the lagging audio signal, generate a second frame of the at least one encoded signal based on the first audio signal and a second modified version of the second audio signal, the second modified version of the second audio signal generated by adjusting the second audio signal based on the second mismatch value, wherein the second mismatch value is adjusted based on the first mismatch value; and

a transmitter configured to transmit the at least one encoded signal.

2. The device of claim 1 , wherein second samples of the lagging audio signal are temporally delayed relative to first samples of the leading audio signal.

3. The device of claim 2 , wherein the first samples and the second samples correspond to the same sound emitted from a sound source.

4. The device of claim 1 , wherein adjusting the second audio signal based on the first mismatch value includes temporally offsetting the second audio signal based on the first mismatch value.

5. The device of claim 1 , wherein the encoder is configured to, based on determining that the second mismatch value is greater than the first mismatch value, adjust the second audio signal by dropping a subset of samples of the second audio signal, and wherein the subset of samples corresponds to frame boundaries.

6. The device of claim 1 , wherein the encoder is configured to, based on determining that the second mismatch value is less than the first mismatch value, adjust the second audio signal by repeating a subset of samples of the second audio signal, and wherein the subset of samples corresponds to frame boundaries.

7. The device of claim 1 , wherein the encoder is configured to, based on determining that the second mismatch value is equal to the first mismatch value, adjust the second audio signal by temporally offsetting the second audio signal based on the second mismatch value.

8. The device of claim 1 , wherein the second frame of the at least one encoded signal is based on first samples of the first audio signal and second samples of the second modified version of the second audio signal.

9. The device of claim 1 , wherein the transmitter is further configured to transmit the second mismatch value associated with the second frame of the at least one encoded signal.

10. The device of claim 1 , wherein the encoder is further configured to determine a non-causal mismatch value by applying an absolute value function to the second mismatch value, and wherein the transmitter is further configured to transmit the non-causal mismatch value associated with the second frame of the at least one encoded signal.

11. The device of claim 1 , wherein the transmitter is further configured to transmit a gain parameter associated with the second frame of the at least one encoded signal, and wherein a value of the gain parameter is based on the first audio signal and the second modified version of the second audio signal.

12. The device of claim 1 , wherein the transmitter is further configured to transmit a reference signal indicator indicating that the first audio signal is determined to be the leading audio signal associated with the second frame of the at least one encoded signal.

13. The device of claim 1 , wherein the at least one encoded signal includes a mid signal, a side signal, or both.

14. The device of claim 1 , wherein the first audio signal includes one of a right signal or a left signal, and wherein the second audio signal includes the other of the right signal or the left signal.

15. The device of claim 1 , wherein the encoder is configured to generate the at least one encoded signal based on adjusting one of the first audio signal and the second audio signal.

16. The device of claim 1 , wherein the encoder is configured to generate the second modified version of the second audio signal by performing a non-causal shift based on an offset value to adjust the second audio signal, and wherein the second mismatch value indicates the offset value associated with the second frame of the at least one encoded signal.

17. The device of claim 1 , wherein the encoder is configured to:
determine a plurality of mismatch values based on the first mismatch value and the second mismatch value;
generate comparison values based on the first audio signal, the second audio signal, and the plurality of mismatch values; and
determine a particular mismatch value based on the comparison values,
wherein the second frame is based on the second modified version of the second audio signal that is generated by adjusting the second audio signal based on the particular mismatch value.

18. The device of claim 1 , wherein the encoder is further configured to, in response to determining that the first audio signal is the lagging audio signal and the second audio signal is the leading audio signal during a third period subsequent to the second period, generate a third frame of the at least one encoded signal based on a third mismatch value that indicates no time shift.

19. The device of claim 18 , wherein the encoder is further configured to generate a reference signal indicator that indicates that the first audio signal is the leading audio signal associated with the third frame of the at least one encoded signal.

20. The device of claim 1 , further comprising:
a first input interface configured to receive the first audio signal from a first microphone; and
a second input interface configured to receive the second audio signal from a second microphone.

21. The device of claim 1 , further comprising a signal comparator configured to determine comparison values based on the first audio signal and the second audio signal, wherein the second mismatch value is based on the comparison values.

22. The device of claim 21 , further comprising a resampler configured to:
generate a first downsampled signal by downsampling the first audio signal; and
generate a second downsampled signal by downsampling the second audio signal,
wherein the comparison values are based on the first downsampled signal and a plurality of mismatch values applied to the second downsampled signal.

23. The device of claim 21 , wherein the comparison values indicate cross-correlation values.

24. The device of claim 21 , wherein the signal comparator is further configured to determine a tentative mismatch value based on the comparison values, and further comprising an interpolator configured to:
generate in

Assignees

• Qualcomm Inc

Inventors

• Atti Venkatraman
• Chebiyyam Venkata Subrahmanyam Chandra Sekhar
• Sinder Daniel Jared

Classifications

• H04R2499/11

  Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's · CPC title

• G10L25/51

  for comparison or discrimination · CPC title

• G10L19/005 Primary

  Correction of errors induced by the transmission channel, if related to the coding algorithm · CPC title

• G10L25/06

  the extracted parameters being correlation coefficients · CPC title

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title