US 12,327,567 B2
Downmixed signal calculation method and apparatus
Haiting Li, Beijing (CN); Zexin Liu, Beijing (CN); and Bin Wang, Shenzhen (CN)
Assigned to Huawei Technologies Co., Ltd., Shenzhen (CN)
Filed by HUAWEI TECHNOLOGIES CO., LTD., Guangdong (CN)
Filed on Nov. 29, 2023, as Appl. No. 18/523,738.
Application 18/523,738 is a continuation of application No. 17/102,190, filed on Nov. 23, 2020, granted, now 11,869,517.
Application 17/102,190 is a continuation of application No. PCT/CN2019/070116, filed on Jan. 2, 2019.
Claims priority of application No. 201810549905.2 (CN), filed on May 31, 2018.
Prior Publication US 2024/0105188 A1, Mar. 28, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G10L 19/008 (2013.01); G10L 25/18 (2013.01); G10L 25/21 (2013.01); H04S 1/00 (2006.01)
CPC G10L 19/008 (2013.01) [G10L 25/18 (2013.01); G10L 25/21 (2013.01); H04S 1/007 (2013.01); H04S 2420/03 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A downmixed signal calculation method, comprising:
converting a continuous stereo audio analog signal into a stereo audio digital signal;
obtaining a first downmixed signal in a current frame when a previous frame of the current frame of the stereo audio digital signal is not a switching frame and a residual signal in the previous frame is not encoded or when the current frame is not a switching frame and a residual signal in the current frame is not encoded, wherein the switching frame is a frame switched from encoding residual signal to not encoding residual signal, wherein the obtaining comprises:
obtaining a second downmixed signal in the current frame;
obtaining a downmix compensation factor of the current frame wherein the obtaining the downmix compensation factor of the current frame comprises;
calculating a downmix compensation factor of a subframe i of the current frame based on a left channel frequency-domain signal in the subframe i of the current frame and the right channel frequency-domain signal in the subframe i of the current frame, wherein
a downmix compensation factor αi(b) in a subband b in the subframe i of the current frame is calculated according to the following formula:

OG Complex Work Unit Math
E_Li(b)=Σk=band_limits(b)k=band_limits(b+1)−1Lib″(k)2, E_Ri(b)=Σk=band_limits(b)k=band_limits(b+1)−1Rib″(k)2, and E_LRi(b)=Σk=band_limits(b)k=band_limits(b+1)−1[Lib″(k)+Rib″(k)]2; or
E_Li(b)=Σk=band_limits(b)k=band_limits(b+1)−1Lib′(k)2, E_Ri(b)=Σk=band_limits(b)k=band_limits(b+1)−1Rib′(k)2, and E_LRi(b)=Σk=band_limits(b)k=band_limits(b+1)−1[Lib′(k)+Rib′(k)]2; wherein
E_Li(b) represents an energy sum of a left channel frequency-domain signal in the subband b in the subframe i of the current frame; E_Ri(b) represents an energy sum of a right channel frequency-domain signal in the subband b in the subframe i of the current frame; E_LRi(b) represents an energy sum of the energy of the left channel frequency-domain signal and the energy of the right channel frequency-domain signal in the subband b in the subframe i of the current frame; band_limits (b) represents a minimum frequency bin index value of the subband b in the subframe i of the current frame; band_limits (b+1) represents a minimum frequency bin index value of a subband b+1 in the subframe i of the current frame; Lib″(k) represents a left channel frequency-domain signal that is in the subband b in the subframe i of the current frame and that is obtained after adjustment based on a stereo parameter; Rib″(k) represents a right channel frequency-domain signal that is in the subband b in the subframe i of the current frame and that is obtained after adjustment based on the stereo parameter, Lib′(k) represents a left channel frequency-domain signal that is in the subband b in the subframe i of the current frame and that is obtained after time-shift adjustment; Rib′(k) represents a right channel frequency-domain signal that is in the subband b in the subframe i of the current frame and that is obtained after time-shift adjustment; and k represents a frequency bin index value, wherein each subframe of the current frame comprises M subbands, the downmix compensation factor of the subframe i of the current frame comprises the downmix compensation factor of the subband b in the subframe i of the current frame, b is an integer, b∈[0, M−1], and M≥2; and
correcting the second downmixed signal in the current frame based on the downmix compensation factor of the current frame, to obtain the first downmixed signal in the current frame; and
determining the first downmixed signal in the current frame as a downmixed signal in a preset frequency band of the current frame.