def update(frames):
    if self.stream.is_active():
        slice = self.left.get_sample_slice(frames, frames + self.window)
        self.stream.write(slice.raw_data)
        y = np.array(slice.get_array_of_samples()) / 1000000
        # yft = np.abs(np.fft.fft(y)) / self.window
        lf.set_ydata(y)
    return lf,