spectrogram.py 文件源码

def save_fft(fil,audio_in):
    samples = len(audio_in)
    fft_size = 2**int(floor(log(samples)/log(2.0)))
    freq = fft(audio_in[0:fft_size])
    s_data = numpy.zeros(fft_size/2)
    x_data = numpy.zeros(fft_size/2)
    peak = 0;
    for j in xrange(fft_size/2):
        if (abs(freq[j]) > peak):
            peak = abs(freq[j])

    for j in xrange(fft_size/2):
        x_data[j] = log(2.0*(j+1.0)/fft_size);
        if (x_data[j] < -10):
            x_data[j] = -10
        s_data[j] = 10.0*log(abs(freq[j])/peak)/log(10.0)
    plt.ylim([-50,0])
    plt.plot(x_data,s_data)
    plt.title('fft log power')
    plt.grid()

    fields = fil.split('.')
    plt.savefig(fields[0]+'_fft.png', bbox_inches="tight")
    plt.clf()
    plt.close()