pyACA.FeatureTimeMaxAcf Namespace Reference

Functions
	FeatureTimeMaxAcf (x, iBlockLength, iHopLength, f_s, f_max=2000, fMinThresh=0.35)
	finds the maximum of the ACF of an audio signal

Function Documentation

FeatureTimeMaxAcf()

FeatureTimeMaxAcf	(		x,
			iBlockLength,
			iHopLength,
			f_s,
			f_max = 2000,
			fMinThresh = 0.35 )

finds the maximum of the ACF of an audio signal

Parameters

x	array with floating point audio data (dimension samples x channels)
iBlockLength	block length in samples
iHopLength	hop length in samples
f_s	sample rate of audio data
f_max	maximum frequency to look at (default: 2000)
fMinThresh	minimum threshold for avoidance of main lobe (default: 0.35)

Returns

vta: autocorrelation maximum

t: time stamp

Definition at line 18 of file FeatureTimeMaxAcf.py.

def FeatureTimeMaxAcf(x, iBlockLength, iHopLength, f_s, f_max=2000, fMinThresh=0.35):
 
    # create blocks
    x_b, t = pyACA.ToolBlockAudio(x, iBlockLength, iHopLength, f_s)
 
    # number of results
    iNumOfBlocks = x_b.shape[0]
 
    # allocate memory
    vacf = np.zeros(iNumOfBlocks)
 
    for n, block in enumerate(x_b):
        eta_min = np.floor(f_s / f_max).astype(int)
 
        # calculate the acf if nonzero
        if not block.sum():
            continue
        else:
            afCorr = np.correlate(block, block, "full") / np.dot(block, block)
 
        afCorr = afCorr[np.arange(iBlockLength, afCorr.size)]
 
        # update eta_min to avoid main lobe
        eta_tmp = np.argmax(afCorr < fMinThresh)
        eta_min = np.max([eta_min, eta_tmp])
 
        afDeltaCorr = np.diff(afCorr)
        eta_tmp = np.argmax(afDeltaCorr > 0)
        eta_min = np.max([eta_min, eta_tmp])
 
        # find the coefficients specified in eta
        vacf[n] = np.max(np.abs(afCorr[np.arange(eta_min + 1, afCorr.size)]))
 
    return vacf, t