feature_extractor.py 文件源码

def get_fft_mel_mat(nfft, sr=8000, nfilts=None, width=1.0, minfrq=20, maxfrq=None, constamp=0):
    if nfilts is None:
        nfilts = nfft
    if maxfrq is None:
        maxfrq = sr // 2
    wts = np.zeros((nfilts, nfft//2+1))
    fftfrqs = np.arange(0, nfft//2+1) / (1. * nfft) * (sr)
    minmel = hz2mel(minfrq)
    maxmel = hz2mel(maxfrq)
    binfrqs = mel2hz(minmel + np.arange(0, nfilts+2) / (nfilts+1.) * (maxmel - minmel))
    # binbin = np.round(binfrqs / maxfrq * nfft)
    for i in range(nfilts):
        fs = binfrqs[[i+0, i+1, i+2]]
        fs = fs[1] + width * (fs - fs[1])
        loslope = (fftfrqs - fs[0]) / (fs[1] - fs[0])
        hislope = (fs[2] - fftfrqs) / (fs[2] - fs[1])
        wts[i, :] = np.maximum(0, np.minimum(loslope, hislope))
    return wts