thinkdsp.py 文件源码

def make_spectrogram(self, seg_length, window_func=np.hamming):
        """Computes the spectrogram of the wave.

        seg_length: number of samples in each segment
        window_func: function used to compute the window

        returns: Spectrogram
        """
        n = len(self.ys)
        window = window_func(seg_length)

        start, end, step = 0, seg_length, seg_length / 2
        spec_map = {}

        while end < n:
            ys = self.ys[start:end] * window
            hs = np.fft.rfft(ys)

            t = (start + end) / 2.0 / self.framerate
            spec_map[t] = Spectrum(hs, self.framerate)

            start += step
            end += step

        return Spectrogram(spec_map, seg_length, window_func)