Encoding of multiple audio signals

Patent metadata

Field	Value
Publication number	US-10152977-B2
Application number	US-201615274041-A
Country	US
Kind code	B2
Filing date	Sep 23, 2016
Priority date	Nov 20, 2015
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

A device includes an encoder. The encoder is configured to receive two audio channels. The encoder is also configured to determine a mismatch value indicative of an amount of a temporal mismatch between the two audio channels. The encoder is further configured to determine, based on the mismatch value, at least one of a target channel or a reference channel. The target channel corresponds to a lagging audio channel of the two audio channels and the reference channel corresponds to a leading audio channel of the two audio channels. The encoder is also configured to generate a modified target channel by adjusting the target channel based on the offset value. The encoder is further configured to generate at least one encoded channel based on the reference channel and the modified target channel.

First claim

What is claimed is:

1. A device comprising:
an encoder configured to:
receive two audio channels;
determine a mismatch value indicative of an amount of a temporal mismatch between the two audio channels;
determine, based on the mismatch value, that a first audio channel of the two audio channels is a leading audio channel of the two audio channels and that a second audio channel of the two audio channels is the lagging audio channel;
in response to determining that the first audio channel of the two audio channels is the leading audio channel and the second audio channel of the two audio channels is the lagging audio channel:
generate a modified second audio channel by adjusting the second audio channel based on the mismatch value; and
generate a first frame of at least one encoded channel based on the first audio channel and the modified second audio channel; and

in response to determining that the first audio channel is the lagging audio channel and the second audio channel is the leading audio channel during a period after generating the first frame of the at least one encoded channel, generate a second frame of the at least one encoded channel based on a second mismatch value, wherein the second mismatch value indicates no time shift between the two audio channels.

2. The device of claim 1 , wherein the encoder is configured to generate the modified second audio channel by shifting the second audio channel based on an offset value, and wherein the mismatch value indicates the offset value.

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

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

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

6. The device of claim 1 , further comprising a transmitter configured to transmit the at least one encoded channel.

7. The device of claim 6 , wherein the transmitter is further configured to transmit the mismatch value.

8. The device of claim 6 , wherein the encoder is further configured to determine a non-causal mismatch value by applying an absolute value function to the mismatch value, and wherein the transmitter is further configured to transmit the non-causal mismatch value.

9. The device of claim 6 , wherein the transmitter is further configured to transmit a gain parameter, and wherein a value of the gain parameter is based on the first audio channel and the modified second audio channel.

10. The device of claim 6 , wherein the transmitter is further configured to transmit a reference channel indicator indicating whether the first audio channel or the second audio channel is determined to be the reference channel.

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

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

13. The device of claim 1 , wherein the encoder is configured to generate the at least one encoded channel based on adjusting a single channel of the two audio channels.

14. The device of claim 1 , wherein the encoder is configured to adjust the second audio channel by performing a non-causal shift based on the mismatch value.

15. The device of claim 1 , wherein the encoder is configured to:
generate comparison values based on the two audio channels;
determine a tentative mismatch value based on the comparison values;
generate interpolated comparison values by performing interpolation on the comparison values; and
determine an interpolated mismatch value based on the interpolated comparison values, the mismatch value based on the interpolated mismatch value.

16. The device of claim 1 , wherein the encoder is further configured to generate a reference channel indicator that indicates that the first audio channel is the reference channel associated with the second frame of the at least one encoded channel.

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

18. The device of claim 1 , further comprising a signal comparator configured to determine comparison values based on the two audio channels, wherein the mismatch value is based on the comparison values.

19. The device of claim 18 , further comprising a resampler configured to:
generate a first downsampled channel by downsampling the first audio channel; and
generate a second downsampled channel by downsampling the second audio channel,
wherein the comparison values are based on the first downsampled channel and a plurality of mismatch values applied to the second downsampled channel.

20. The device of claim 18 , wherein the comparison values indicate cross-correlation values.

21. The device of claim 18 , 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 interpolated comparison values corresponding to mismatch values that are proximate to the tentative mismatch value by performing interpolation on the comparison values; and
determine an interpolated mismatch value based on the interpolated comparison values,
wherein the mismatch value is based on the interpolated mismatch value.

22. The device of claim 1 , further comprising a shift change analyzer configured to:
determine a first mismatch value corresponding to a previous adjustment of one of the two audio channels to generate a first particular frame of the at least one encoded channel; and
determine an amended mismatch value based on comparison values corresponding to the two audio channels,
wherein the mismatch value is based on a comparison of the amended mismatch value and the first mismatch value.

23. The device of claim 1 , wherein the encoder is integrated into a mobile device.

24. The device of claim 1 , wherein the encoder is integrated into a base station.

25. A method of communication comprising:
receiving, at a device, two audio channels;
generating, at the device, comparison values based on the two audio channels;
determining, at the device, a tentative mismatch value based on the comparison values;
generating, at the device, interpolated comparison values by performing interpolation on the comparison values;
determining, at the device, an interpolated mismatch value based on the interpolated comparison values;
determining, at the device, a mismatch value based on the interpolated mismatch value, the mismatch value indicative of an amount of temporal mismatch between two audio channels;
determining, based on the mismatch value, at least one of a target channel or a reference channel, the target channel corresponding to a lagging audio channel of the two audio channels and the reference channel corresponding to a leading audio channel of the two audio channels;
generating, at the device, a modified target channel by adjusting t

Assignees

• Qualcomm Inc

Inventors

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

Classifications

• G10L21/00

  Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility (G10L19/00 takes precedence) · 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

• G10L25/51

  for comparison or discrimination · CPC title

• H04R2499/11

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