datsegment.py 文件源码

def amplitude_stream(data, sr, fftn, step, lowcut, highcut):
    '''returns an iterator with the start time in seconds
    and threshold value for each chunk'''
    from scipy.signal import hamming
    all_fft_freqs = np.fft.fftfreq(fftn, sr** -1)
    fft_freqs = (all_fft_freqs >= lowcut) & (all_fft_freqs <= highcut)
    window = hamming(fftn)
    data = data.ravel()
    for i in range(0, len(data) - fftn, step):
        x = data[i:i + fftn] * window
        fft = np.fft.fft(x, fftn)[fft_freqs]
        time = (i + fftn / 2) / sr
        yield time, np.mean(np.log(np.abs(fft)))