Bandwidth Extension System and Approach
AssigneeHuawei Technologies Co., Ltd.
InventorYang Gao
Life of this patent
Estimating the term…
Abstract
A method of performing BandWidth Extension (BWE) includes a frequency band shifting approach to generate an extended high band signal in time domain and a gain determination approach of controlling the energy of the extended high band. The proposed approach allows shifting any size of low band to any size of high band. The BWE scaling gain is estimated by using available filter bank coefficients with extremely low bit rate or without costing any bit, combining three possible gain factors.
Claims15
A frequency band shifting method of generating an extended high band signal from low frequency band in time domain, the method comprising:
- up-sampling a baseband audio signal to have a baseband up-sampled signal;
- mirroring the baseband audio signal to have a baseband mirrored signal;
- up-sampling and low-pass filtering the baseband mirrored signal with non-symmetric low-pass-filtering to have a high band mirrored signal;
- and
- mirroring again the high band mirrored signal to have an extra high band signal.
A bandwidth extension method of generating an extended high band signal by shifting a low frequency band in time domain, the method comprising:
- up-sampling a baseband audio signal to have a baseband up-sampled signal;
- mirroring the baseband audio signal to have a baseband mirrored signal;
- up-sampling and low-pass filtering the baseband mirrored signal with non-symmetric low-pass-filtering to have a high band mirrored signal;
- mirroring again the high band mirrored signal to have an extra high band signal;
- scaling and shaping the extra high band signal to have a scaled extra high band signal;
- and
- adding the scaled extra high band signal to the baseband up-sampled signal to have the final output signal with bandwidth extension.
A bandwidth extension method of generating an extended high band signal by shifting a low frequency band in time domain, the method comprising:
- up-sampling a baseband audio signal to have a baseband up-sampled signal;
- mirroring the baseband audio signal to have a baseband mirrored signal;
- up-sampling and low-pass filtering the baseband mirrored signal with non-symmetric low-pass-filtering to have a high band mirrored signal;
- mirroring again the high band mirrored signal to have an extra high band signal;
- scaling and shaping the extra high band signal to have a scaled extra high band signal;
- adding proper noise component to the scaled extra high band signal to have a final extra high band signal;
- and
- adding the final scaled extra high band signal to the baseband up-sampled signal to have the final output signal with bandwidth extension.
A method of estimating a bandwidth extension scaling gain by using available filter bank coefficients with extremely low bit rate or without costing any bit, the method comprising combining three gain factors:
- determining Gain_t[ ] to sharpen time evaluation energy envelope;
- determining Gain_1[ ] from nearest available high band filter bank coefficients;
- and
- determining Gain_2[ ] by considering energy ratio between energy at lowest frequency area and lowest energy in all available subbands.
Dependencies are inferred from the claim text.