Delay estimation method and apparatus

Patent metadata

Field	Value
Publication number	US-11950079-B2
Application number	US-202217689328-A
Country	US
Kind code	B2
Filing date	Mar 8, 2022
Priority date	Jun 29, 2017
Publication date	Apr 2, 2024
Grant date	Apr 2, 2024

Abstract

A delay estimation method includes determining a cross-correlation coefficient of a multi-channel signal of a current frame, determining a delay track estimation value of the current frame based on buffered inter-channel time difference information of at least one past frame, determining an adaptive window function of the current frame, performing weighting on the cross-correlation coefficient based on the delay track estimation value of the current frame and the adaptive window function of the current frame, to obtain a weighted cross-correlation coefficient, and determining an inter-channel time difference of the current frame based on the weighted cross-correlation coefficient.

First claim

What is claimed is:

1. A delay estimation method, comprising:
determining a cross-correlation coefficient of a multi-channel signal of a current frame;
determining a delay track estimation value of the current frame based on buffered inter-channel time difference information of at least one past frame; wherein determining the delay track estimation value of the current frame comprises: performing delay track estimation based on the buffered inter-channel time difference information of the at least one past frame; and using a linear regression method to determine the delay track estimation value of the current frame; or wherein determining the delay track estimation value of the current frame comprises: performing delay track estimation based on the buffered inter-channel time difference information of the at least one past frame; and using a weighted linear regression method to determine the delay track estimation value of the current frame;
determining an adaptive parameter of an adaptive window function of the current frame based on a coding parameter of the at least one past frame, wherein the coding parameter indicates a first type of the at least one past frame or a second type of the at least one past frame on which time-domain downmixing processing is performed;
determining the adaptive window function of the current frame according to the adaptive parameter;
performing weighting on the cross-correlation coefficient, based on the delay track estimation value and the adaptive window function, to obtain a weighted cross-correlation coefficient; and
determining an inter-channel time difference of the current frame based on the weighted cross-correlation coefficient.

2. The delay estimation method of claim 1 , wherein after determining the inter-channel time difference of the current frame, the delay estimation method further comprises updating the buffered inter-channel time difference information of the at least one past frame, and wherein the buffered inter-channel time difference information of the at least one past frame is an inter-channel time difference smoothed value of the at least one past frame or a second inter-channel time difference of the at least one past frame.

3. The delay estimation method of claim 2 , wherein the buffered inter-channel time difference information of the at least one past frame is the inter-channel time difference smoothed value of the at least one past frame, wherein updating the buffered inter-channel time difference information of the at least one past frame comprises:
determining a second inter-channel time difference smoothed value of the current frame based on the delay track estimation value of the current frame and the inter-channel time difference of the current frame; and
updating a buffered inter-channel time difference smoothed value of the at least one past frame based on the second inter-channel time difference smoothed value of the current frame, wherein the second inter-channel time difference smoothed value of the current frame is calculated using a formula comprising:
cur_itd_smooth=φ*reg_prv_corr+(1−φ)*cur_itd,

wherein cur_itd_smooth is the second inter-channel time difference smoothed value of the current frame, wherein φ is a second smoothing factor comprising a constant greater than or equal to 0 and less than or equal to 1, wherein reg_prv_corr is the delay track estimation value of the current frame, and wherein cur_itd is the inter-channel time difference of the current frame.

4. The delay estimation method of claim 2 , wherein updating the buffered inter-channel time difference information of the at least one past frame comprises updating the buffered inter-channel time difference information when a first voice activation detection result of the at least one past frame is a first active frame or a second voice activation detection result of the current frame is a second active frame.

5. The delay estimation method of claim 1 , wherein after determining the inter-channel time difference of the current frame, the delay estimation method further comprises updating a buffered weighting coefficient of the at least one past frame, and wherein the buffered weighting coefficient of the at least one past frame is a weighting coefficient in the weighted linear regression method.

6. The delay estimation method of claim 5 , wherein when the adaptive window function of the current frame is determined based on a smoothed inter-channel time difference of the at least one past frame, updating the buffered weighting coefficient of the at least one past frame comprises:
calculating a first weighting coefficient of the current frame based on a smoothed inter-channel time difference estimation deviation of the current frame; and
updating a buffered first weighting coefficient of the at least one past frame based on the first weighting coefficient of the current frame,
wherein the first weighting coefficient of the current frame is calculated using formulas comprising:
wgt_par1 =a _wgt1*smooth_dist_reg_update+ b _wgt1;
a _wgt1=( xl _wgt1 −xh _wgt1)/( yh _dist1 ′−yl _dist1′); and

b _wgt1 =xl _wgt1 −a _wgt1* yh _dist1′,

wherein wgt_par 1 is the first weighting coefficient of the current frame, wherein smooth_dist_reg_update is the smoothed inter-channel time difference estimation deviation of the current frame, wherein xh_wgt is an upper limit value of the first weighting coefficient, wherein xl_wgt is a lower limit value of the first weighting coefficient, wherein yh _dist1′ is a first smoothed inter-channel time difference estimation deviation corresponding to the upper limit value of the first weighting coefficient, wherein yl_dist1′ is a second smoothed inter-channel time difference estimation deviation corresponding to the lower limit value of the first weighting coefficient, and wherein yh _dist1′, yl_dist1′, xh_wgt1, and xl_wgt1 are all positive numbers.

7. The delay estimation method of claim 6 , wherein the first weighting coefficient of the current frame is further calculated using additional formulas comprising:
wgt_par1=min(wgt_par1 ,xh _wgt1); and
wgt_par1=max(wgt_par1 ,xl _wgt1),
wherein min represents taking of a minimum value, and wherein max represents taking of a maximum value.

8. The delay estimation method of claim 5 , wherein when the adaptive window function of the current frame is determined based on an inter-channel time difference estimation deviation of the current frame, updating the buffered weighting coefficient of the at least one past frame comprises:
calculating a second weighting coefficient of the current frame based on the inter-channel time difference estimation deviation of the current frame; and
updating a buffered second weighting coefficient of the at least one past frame based on the second weighting coefficient of the current frame.

9. The delay estimation method of claim 5 , wherein updating the buffered weighting coefficient of the at least one past frame comprises updating the buffered weighting coefficient of the at least one past frame when a first voice activation detection result of the at least one past frame is a first active frame or a second voice activation detection result of the current frame is a second active frame.

10. An audio coding device comprising:
at least one processor; and
one or more memories coupled to the at least one processor and configured to store programming instructions for execution by the at least one processor to cause the audio coding device to:
determine a cross-correlation coefficient of a multi-channel signal of a current frame;
determine a delay track estimation value of the current frame based on buffered inter-channel time difference information o

Assignees

• Huawei Tech Co Ltd

Inventors

• Shlomot Eyal
• Li Haiting
• Miao Lei

Classifications

• H04S1/007 Primary

  in which the audio signals are in digital form (data reduction aspects thereof based on psychoacoustics G10L19/02) · CPC title

• H04S5/00

  Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation · CPC title

• H04S2400/03

  Aspects of down-mixing multi-channel audio to configurations with lower numbers of playback channels, e.g. 7.1 -> 5.1 (H04S2400/01 takes precedence) · CPC title

• H04S2400/05

  Generation or adaptation of centre channel in multi-channel audio systems · 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