| """Residual acoustic echo delay estimation; no recording or guessed delay.""" |
| import numpy as np |
| from scipy.signal import correlate,correlation_lags |
|
|
|
|
| def estimate_echo_delay(mic,reference,sr=16000,max_delay=.45): |
| mic=np.asarray(mic,np.float64);reference=np.asarray(reference,np.float64) |
| n=min(len(mic),len(reference));mic=mic[:n];reference=reference[:n] |
| if n<sr//2 or np.linalg.norm(mic)<1e-5 or np.linalg.norm(reference)<1e-5: |
| return {'available':False,'reason':'No measurable reference/echo','confidence':0.} |
| corr=correlate(mic,reference,mode='full',method='fft');lags=correlation_lags(n,n) |
| keep=(lags>=0)&(lags<=round(max_delay*sr));indexes=np.flatnonzero(keep) |
| index=indexes[np.argmax(corr[keep])];lag=int(lags[index]) |
| a=mic[lag:];b=reference[:n-lag] |
| confidence=float(np.dot(a,b)/max(np.linalg.norm(a)*np.linalg.norm(b),1e-10)) |
| available=confidence>=.45 |
| return {'available':available,'delay_ms':lag/sr*1000 if available else None, |
| 'confidence':confidence,'reason':'Measured acoustic residual' if available else 'Echo cancellation/noise makes delay uncertain'} |
|
|
