reassignment.py 文件源码

def __init__(self, signal_frames, window=scipy.hanning, positive_only=True):
        """
        :param signal_frames: signal represented as SignalFrames instance
        :param window: STFT window function - produces 1D window which will
        be normalized
        """
        self.signal_frames = signal_frames

        x_frames = signal_frames.frames
        w = normalized_window(window(signal_frames.frame_size))

        # complex spectra of windowed blocks of signal - STFT
        self.X_complex = np.fft.fft(x_frames * w)
        # linear magnitude spectrogram
        self.X_mag = abs(self.X_complex) / self.X_complex.shape[1]

        # spectra of signal shifted in time

        # This fakes looking at the previous frame shifted by one sample.
        # In order to work only with one frame of size N and not N + 1, we fill the
        # missing value with zero. This should not introduce a large error, since the
        # borders of the amplitude frame will go to zero anyway due to applying a
        # window function in the STFT tranform.
        X_prev_time = np.fft.fft(shift_right(x_frames) * w)

        # spectra shifted in frequency
        X_prev_freq = shift_right(self.X_complex)

        # cross-spectra - ie. spectra of cross-correlation between the
        # respective time-domain signals
        X_cross_time = cross_spectrum(self.X_complex, X_prev_time)
        X_cross_freq = cross_spectrum(self.X_complex, X_prev_freq)

        # instantaneous frequency estimates
        # normalized frequencies in range [0.0, 1.0] - from DC to sample rate
        self.X_inst_freqs = estimate_instant_freqs(X_cross_time)
        # instantaneous group delay estimates
        # relative coordinates within the frame with range [-0.5, 0.5] where
        # 0.0 is the frame center
        self.X_group_delays = estimate_group_delays(X_cross_freq)

        if positive_only:
            self.X_mag = positive_freq_magnitudes(self.X_mag)
            self.X_complex, self.X_inst_freqs, self.X_group_delays = [
                select_positive_freq_fft(values) for values in
                [self.X_complex, self.X_inst_freqs, self.X_group_delays]
            ]