python类hanning()的实例源码

def stft(sig, frameSize, overlapFac=0.75, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frameSize)
    hopSize = int(frameSize - np.floor(overlapFac * frameSize))
    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    # samples = np.append(np.zeros(np.floor(frameSize / 2.0)), sig)
    samples = np.array(sig, dtype='float64')
    # cols for windowing
    cols = np.ceil((len(samples) - frameSize) / float(hopSize)) + 1
    # zeros at end (thus samples can be fully covered by frames)
    # samples = np.append(samples, np.zeros(frameSize))
    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frameSize),
        strides=(samples.strides[0] * hopSize, samples.strides[0])).copy()
    frames *= win
    return np.fft.rfft(frames)


# all the definition of the flowing variable can be found
# train_net.py

def hanning(M):
    """Returns the Hanning window.

    The Hanning window is defined as

    .. math::
        w(n) = 0.5 - 0.5\\cos\\left(\\frac{2\\pi{n}}{M-1}\\right)
        \\qquad 0 \\leq n \\leq M-1

    Args:
        M (:class:`~int`):
            Number of points in the output window. If zero or less, an empty
            array is returned.

    Returns:
        ~cupy.ndarray: Output ndarray.

    .. seealso:: :func:`numpy.hanning`
    """
    if M < 1:
        return from_data.array([])
    if M == 1:
        return basic.ones(1, float)
    n = ranges.arange(0, M)
    return 0.5 - 0.5 * trigonometric.cos(2.0 * numpy.pi * n / (M - 1))

def ams_extractor(x, sr, win_len, shift_len, order):
    from scipy.signal import hilbert
    envelope = np.abs(hilbert(x))
    for i in range(order-1):
        envelope = np.abs(hilbert(envelope))
    envelope = envelope * 1./3.
    frames = (len(envelope) - win_len) // shift_len
    hanning_window = np.hanning(win_len)
    ams_feature = np.zeros(shape=(15, frames))
    wts = cal_triangle_window(0, sr//2, win_len, 15, 15.6, 400)
    for i in range(frames):
        one_frame = x[i*shift_len:i*shift_len+win_len]
        one_frame = one_frame * hanning_window
        frame_fft = np.abs(np.fft.fft(one_frame, win_len))
        ams_feature[:,i] = np.matmul(wts, frame_fft)
    return ams_feature

def cochleagram_extractor(xx, sr, win_len, shift_len, channel_number, win_type):
    fcoefs, f = make_erb_filters(sr, channel_number, 50)
    fcoefs = np.flipud(fcoefs)
    xf = erb_frilter_bank(xx, fcoefs)

    if win_type == 'hanning':
        window = np.hanning(channel_number)
    elif win_type == 'hamming':
        window = np.hamming(channel_number)
    elif win_type == 'triangle':
        window = (1 - (np.abs(channel_number - 1 - 2 * np.arange(1, channel_number + 1, 1)) / (channel_number + 1)))
    else:
        window = np.ones(channel_number)
    window = window.reshape((channel_number, 1))

    xe = np.power(xf, 2.0)
    frames = 1 + ((np.size(xe, 1)-win_len) // shift_len)
    cochleagram = np.zeros((channel_number, frames))
    for i in range(frames):
        one_frame = np.multiply(xe[:, i*shift_len:i*shift_len+win_len], np.repeat(window, win_len, 1))
        cochleagram[:, i] = np.sqrt(np.mean(one_frame, 1))

    cochleagram = np.where(cochleagram == 0.0, np.finfo(float).eps, cochleagram)
    return cochleagram

def log_power_spectrum_extractor(x, win_len, shift_len, win_type, is_log=False):
    samples = x.shape[0]
    frames = (samples - win_len) // shift_len
    stft = np.zeros((win_len, frames), dtype=np.complex64)
    spect = np.zeros((win_len // 2 + 1, frames), dtype=np.float64)

    if win_type == 'hanning':
        window = np.hanning(win_len)
    elif win_type == 'hamming':
        window = np.hamming(win_len)
    elif win_type == 'rectangle':
        window = np.ones(win_len)

    for i in range(frames):
        one_frame = x[i*shift_len: i*shift_len+win_len]
        windowed_frame = np.multiply(one_frame, window)
        stft[:, i] = np.fft.fft(windowed_frame, win_len)
        if is_log:
            spect[:, i] = np.log(np.power(np.abs(stft[0: win_len//2+1, i]), 2.))
        else:
            spect[:, i] = np.power(np.abs(stft[0: win_len//2+1, i]), 2.)

    return spect

def stft_extractor(x, win_len, shift_len, win_type):
    samples = x.shape[0]
    frames = (samples - win_len) // shift_len
    stft = np.zeros((win_len, frames), dtype=np.complex64)
    spect = np.zeros((win_len // 2 + 1, frames), dtype=np.complex64)

    if win_type == 'hanning':
        window = np.hanning(win_len)
    elif win_type == 'hamming':
        window = np.hamming(win_len)
    elif win_type == 'rectangle':
        window = np.ones(win_len)

    for i in range(frames):
        one_frame = x[i*shift_len: i*shift_len+win_len]
        windowed_frame = np.multiply(one_frame, window)
        stft[:, i] = np.fft.fft(windowed_frame, win_len)
        spect[:, i] = stft[: win_len//2+1, i]

    return spect

def ams_extractor(x, sr, win_len, shift_len, order=1, decimate_coef=1./4.):
    from scipy.signal import hilbert
    envelope = np.abs(hilbert(x))
    for i in range(order-1):
        envelope = np.abs(hilbert(envelope))
    envelope = envelope * decimate_coef
    frames = (len(envelope) - win_len) // shift_len
    hanning_window = np.hanning(win_len)
    ams_feature = np.zeros(shape=(15, frames))
    wts = cal_triangle_window(0, sr//2, win_len, 15, 15.6, 400)
    for i in range(frames):
        one_frame = x[i*shift_len:i*shift_len+win_len]
        one_frame = one_frame * hanning_window
        frame_fft = np.abs(np.fft.fft(one_frame, win_len))
        ams_feature[:,i] = np.matmul(wts, frame_fft)
    return ams_feature

def unknown_feature_extractor(x, sr, win_len, shift_len, barks, inner_win, inner_shift, win_type, method_version):
    x_spectrum = stft_extractor(x, win_len, shift_len, win_type)
    coef = get_fft_bark_mat(sr, win_len, barks, 20, sr//2)
    bark_spect = np.matmul(coef, x_spectrum)
    ams = np.zeros((barks, inner_win//2+1, (bark_spect.shape[1] - inner_win)//inner_shift))
    for i in range(barks):
        channel_stft = stft_extractor(bark_spect[i, :], inner_win, inner_shift, 'hanning')
        if method_version == 'v1':
            ams[i, :, :] = 20 * np.log(np.abs(channel_stft[:inner_win//2+1, :(bark_spect.shape[1] - inner_win)//inner_shift]))
        elif method_version == 'v2':
            channel_amplitude = np.abs(channel_stft[:inner_win//2+1, :(bark_spect.shape[1] - inner_win)//inner_shift])
            channel_angle = np.angle(channel_stft[:inner_win//2+1, :(bark_spect.shape[1] - inner_win)//inner_shift])
            channel_angle = channel_angle - (np.floor(channel_angle / (2.*np.pi)) * (2.*np.pi))
            ams[i, :, :] = np.power(channel_amplitude, 1./3.) * channel_angle
        else:
            ams[i, :, :] = np.abs(channel_stft)
    return ams

def spectrum_extractor(x, win_len, shift_len, win_type, is_log):
    samples = x.shape[0]
    frames = (samples - win_len) // shift_len
    stft = np.zeros((win_len, frames), dtype=np.complex64)
    spectrum = np.zeros((win_len // 2 + 1, frames), dtype=np.float64)

    if win_type == 'hanning':
        window = np.hanning(win_len)
    elif win_type == 'hamming':
        window = np.hamming(win_len)
    elif win_type == 'triangle':
        window = (1 - (np.abs(win_len - 1 - 2 * np.arange(1, win_len + 1, 1)) / (win_len + 1)))
    else:
        window = np.ones(win_len)
    for i in range(frames):
        one_frame = x[i*shift_len: i*shift_len+win_len]
        windowed_frame = np.multiply(one_frame, window)
        stft[:, i] = np.fft.fft(windowed_frame, win_len)
        if is_log:
            spectrum[:, i] = np.log(np.abs(stft[0: win_len//2+1, i]))
        else:
            spectrum[:, i] = np.abs(stft[0: win_len // 2 + 1:, i])

    return spectrum

def stft(sig, frameSize, overlapFac=0.75, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frameSize)
    hopSize = int(frameSize - np.floor(overlapFac * frameSize))
    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    # samples = np.append(np.zeros(np.floor(frameSize / 2.0)), sig)
    samples = np.array(sig, dtype='float64')
    # cols for windowing
    cols = np.floor((len(samples) - frameSize) / float(hopSize))
    # zeros at end (thus samples can be fully covered by frames)
    # samples = np.append(samples, np.zeros(frameSize))
    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frameSize),
        strides=(samples.strides[0] * hopSize, samples.strides[0])).copy()
    frames *= win
    return np.fft.rfft(frames)

def stft(sig, frameSize, overlapFac=0.75, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frameSize)
    hopSize = int(frameSize - np.floor(overlapFac * frameSize))
    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    # samples = np.append(np.zeros(np.floor(frameSize / 2.0)), sig)
    samples = np.array(sig, dtype='float64')
    # cols for windowing
    cols = np.ceil((len(samples) - frameSize) / float(hopSize)) + 1
    # zeros at end (thus samples can be fully covered by frames)
    # samples = np.append(samples, np.zeros(frameSize))
    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frameSize),
        strides=(samples.strides[0] * hopSize, samples.strides[0])).copy()
    frames *= win
    return np.fft.rfft(frames)

def stft(sig, frameSize, overlapFac=0.75, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frameSize)
    hopSize = int(frameSize - np.floor(overlapFac * frameSize))
    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    # samples = np.append(np.zeros(np.floor(frameSize / 2.0)), sig)
    samples = np.array(sig, dtype='float64')
    # cols for windowing
    cols = np.ceil((len(samples) - frameSize) / float(hopSize)) + 1
    # zeros at end (thus samples can be fully covered by frames)
    samples = np.append(samples, np.zeros(frameSize))
    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frameSize),
        strides=(samples.strides[0] * hopSize, samples.strides[0])).copy()
    frames *= win
    return np.fft.rfft(frames)

def __init__(self, sampling_rate=16000, frame_width=0.032, frame_shift=0.01, num_mel_filters=40, window_func="hanning",
        using_delta=True, using_delta_delta=True):
        assert window_func in ["hanning", "hamming"]
        self.sampling_rate = sampling_rate
        self.frame_width = frame_width
        self.sampling_rate = sampling_rate
        self.frame_width = frame_width
        self.frame_shift = frame_shift
        self.num_fft = int(sampling_rate * frame_width)
        self.num_mel_filters = num_mel_filters

        if window_func == "hanning":
            self.window_func = lambda x:np.hanning(x)
        elif winfunc == "hamming":
            self.window_func = lambda x:np.hamming(x)

        self.using_delta = using_delta
        self.using_delta_delta = using_delta_delta

        self.fbank = fft.get_filterbanks(nfft=self.num_fft, nfilt=num_mel_filters, samplerate=sampling_rate)

def periodic_hann(window_length):
  """Calculate a "periodic" Hann window.

  The classic Hann window is defined as a raised cosine that starts and
  ends on zero, and where every value appears twice, except the middle
  point for an odd-length window.  Matlab calls this a "symmetric" window
  and np.hanning() returns it.  However, for Fourier analysis, this
  actually represents just over one cycle of a period N-1 cosine, and
  thus is not compactly expressed on a length-N Fourier basis.  Instead,
  it's better to use a raised cosine that ends just before the final
  zero value - i.e. a complete cycle of a period-N cosine.  Matlab
  calls this a "periodic" window. This routine calculates it.

  Args:
    window_length: The number of points in the returned window.

  Returns:
    A 1D np.array containing the periodic hann window.
  """
  return 0.5 - (0.5 * np.cos(2 * np.pi / window_length *
                             np.arange(window_length)))

def stft_magnitude(signal, fft_length,
                   hop_length=None,
                   window_length=None):
  """Calculate the short-time Fourier transform magnitude.

  Args:
    signal: 1D np.array of the input time-domain signal.
    fft_length: Size of the FFT to apply.
    hop_length: Advance (in samples) between each frame passed to FFT.
    window_length: Length of each block of samples to pass to FFT.

  Returns:
    2D np.array where each row contains the magnitudes of the fft_length/2+1
    unique values of the FFT for the corresponding frame of input samples.
  """
  frames = frame(signal, window_length, hop_length)
  # Apply frame window to each frame. We use a periodic Hann (cosine of period
  # window_length) instead of the symmetric Hann of np.hanning (period
  # window_length-1).
  window = periodic_hann(window_length)
  windowed_frames = frames * window
  return np.abs(np.fft.rfft(windowed_frames, int(fft_length)))


# Mel spectrum constants and functions.

def compute_pairwise_shifts(imstack):
    # Calculates the pairwise shifts for images in a stack of format [frame, x, y].
    # returns shift vector as [y, x] for each pair, a 2 x N-1 array where N is num_frames

    scan_shape = imstack.shape
    num_pairs = scan_shape[0]-1 
    print('Correcting ' + str(num_pairs) + ' frames...')

    # Prepare window function (Hann)
    win = np.outer(np.hanning(scan_shape[1]),np.hanning(scan_shape[2]))

    # Pairwise shifts
    shift = np.zeros((2, num_pairs))
    for iPair in range(0, num_pairs):
        image = imstack[iPair]
        offset_image = imstack[iPair+1]
        shift[:,iPair], error, diffphase = register_translation_hybrid(image*win, offset_image*win, 
                                                                        exponent = 0.3, upsample_factor = 100)
        # Shifts are defined as [y, x] where y is shift of imaging location 
        # with respect to positive y axis, similarly for x
    return shift

def __init__(self, window_size, segments_buf=None):
        self._window_size = window_size
        if segments_buf is None:
            segments_buf = int(SAMPLE_RATE / window_size)
        self._segments_buf = segments_buf

        self._thresholding_window_size = THRESHOLD_WINDOW_SIZE
        assert self._thresholding_window_size <= segments_buf

        self._last_spectrum = np.zeros(window_size, dtype=np.int16)
        self._last_flux = deque(
            np.zeros(segments_buf, dtype=np.int16), segments_buf)
        self._last_prunned_flux = 0

        self._hanning_window = np.hanning(window_size)
        # The zeros which will be used to double each segment size
        self._inner_pad = np.zeros(window_size)

        # To ignore the first peak just after starting the application
        self._first_peak = True

def managed_window(self,axismanager, data, windowaxis):

        def window_axis_function(a, window):
            a = a * window
            return a

        newaxis = axismanager.current_axis_number(windowaxis)

        N = data.shape[newaxis]
        window = np.hanning(N)

        # Save "window summed and squared" (see Numerical Recipes)
        wss = np.sum(window**2.0)/float(N)

        # Apply window
        windoweddata = np.apply_along_axis(window_axis_function, 
                                           newaxis, data, window)

        return windoweddata, wss

def measureLoop(self):
        """ Measure 10 values, add them to buffer and remove the 10 oldest values.
        """
        if self.stopRequest:
            self.stopRequest = False
            self.unlock()
            return

        data = np.zeros((100,  self._data_logic.getChannels()))
        data[:, 0] = np.array([self._data_logic.getData() for i in range(100)])

        self.buf = np.roll(self.buf, -100, axis=0)
        self.buf[-101:-1] = data
        w = np.hanning(self.window_len)
        s = np.r_[self.buf[self.window_len-1:0:-1], self.buf, self.buf[-1:-self.window_len:-1]]
        for channel in range(self._data_logic.getChannels()):
            convolved = np.convolve(w/w.sum(), s[:, channel], mode='valid')
            self.smooth[:, channel] = convolved
        self.sigRepeat.emit()

def undo_stft(spect, hop_size, frame_len=None, unwindow='auto'):
    """
    Undoes an SFTF via overlap-add, returning a numpy array of samples.
    """
    # transform into time domain
    spect = np.fft.irfft(spect, n=frame_len, axis=1)
    # overlap-and-add
    num_frames, frame_len = spect.shape
    win = np.hanning(frame_len)
    #win = np.sin(np.pi * np.arange(frame_len) / frame_len)
    #win = 1
    if unwindow == 'auto':
        unwindow = (hop_size <= frame_len//2)
    samples = np.zeros((num_frames - 1) * hop_size + frame_len)
    if unwindow:
        factors = np.zeros_like(samples)
    for idx, frame in enumerate(spect):
        oidx = int(idx*hop_size)
        samples[oidx:oidx+frame_len] += frame * win
        if unwindow:
            factors[oidx:oidx+frame_len] += win**2
    if unwindow:
        np.maximum(factors, .1 * factors.max(), factors)
        samples /= factors
    return samples

def stft(sig, frameSize, overlapFac=0.75, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frameSize)
    hopSize = int(frameSize - np.floor(overlapFac * frameSize))
    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    # samples = np.append(np.zeros(np.floor(frameSize / 2.0)), sig)
    samples = np.array(sig, dtype='float64')
    # cols for windowing
    cols = np.ceil((len(samples) - frameSize) / float(hopSize)) + 1
    # zeros at end (thus samples can be fully covered by frames)
    samples = np.append(samples, np.zeros(frameSize))
    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frameSize),
        strides=(samples.strides[0] * hopSize, samples.strides[0])).copy()
    frames *= win
    return np.fft.rfft(frames)

def stft(sig, frameSize, overlapFac=0.75, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frameSize)
    hopSize = int(frameSize - np.floor(overlapFac * frameSize))
    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    # samples = np.append(np.zeros(np.floor(frameSize / 2.0)), sig)
    samples = np.array(sig, dtype='float64')
    # cols for windowing
    cols = np.ceil((len(samples) - frameSize) / float(hopSize)) + 1
    # zeros at end (thus samples can be fully covered by frames)
    samples = np.append(samples, np.zeros(frameSize))
    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frameSize),
        strides=(samples.strides[0] * hopSize, samples.strides[0])).copy()
    frames *= win
    return np.fft.rfft(frames)

def stft(sig, frameSize, overlapFac=0.75, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frameSize)
    hopSize = int(frameSize - np.floor(overlapFac * frameSize))
    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    # samples = np.append(np.zeros(np.floor(frameSize / 2.0)), sig)
    samples = np.array(sig, dtype='float64')
    # cols for windowing
    cols = np.ceil((len(samples) - frameSize) / float(hopSize))
    # zeros at end (thus samples can be fully covered by frames)
    # samples = np.append(samples, np.zeros(frameSize))
    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frameSize),
        strides=(samples.strides[0] * hopSize, samples.strides[0])).copy()
    frames *= win
    return np.fft.rfft(frames)

def test_high_frequency_completion(self):
        path = dirpath + '/data/test16000.wav'
        fs, x = wavfile.read(path)

        f0rate = 0.5
        shifter = Shifter(fs, f0rate=f0rate)
        mod_x = shifter.f0transform(x, completion=False)
        mod_xc = shifter.f0transform(x, completion=True)
        assert len(mod_x) == len(mod_xc)

        N = 512
        fl = int(fs * 25 / 1000)
        win = np.hanning(fl)
        sts = [1000, 5000, 10000, 20000]
        for st in sts:
            # confirm w/o completion
            f_mod_x = fft(mod_x[st: st + fl] / 2**16 * win)
            amp_mod_x = 20.0 * np.log10(np.abs(f_mod_x))

            # confirm w/ completion
            f_mod_xc = fft(mod_xc[st: st + fl] / 2**16 * win)
            amp_mod_xc = 20.0 * np.log10(np.abs(f_mod_xc))

            assert np.mean(amp_mod_x[N // 4:] < np.mean(amp_mod_xc[N // 4:]))

def analysis_with_del_comp_from_est_file(v_in_sig, est_file, fs, nFFT=None, win_func=np.hanning, b_ph_unv_zero=False, nwin_per_pitch_period=0.5):

    if nFFT is None: # If fft length is not provided, some standard values are assumed.
        if fs==48000:
            nFFT=4096
        elif fs==16000:
            nFFT=2048

    # Pitch Marks:-------------------------------------------------------------
    v_pm_sec, v_voi = la.read_reaper_est_file(est_file, check_len_smpls=len(v_in_sig), fs=fs)    
    v_pm_smpls = v_pm_sec * fs

    m_sp, m_ph, v_shift, m_frms, m_fft = analysis_with_del_comp_from_pm(v_in_sig, v_pm_smpls, nFFT, win_func=win_func, nwin_per_pitch_period=nwin_per_pitch_period)

    if b_ph_unv_zero:
        m_ph = m_ph * v_voi[:,None]

    return m_sp, m_ph, v_shift, v_voi, m_frms, m_fft



#==============================================================================
# From (after) 'analysis_with_del_comp':
# new: returns voi/unv decision.

def stft(self, samples, window_size, overlap_factor=0.5, window_function=np.hanning):
        """
        Perform Short-time Fourier transform to get the spectrogram for the given samples

        :param samples: Complex samples
        :param window_size: Size of DFT window
        :param overlap_factor: Value between 0 (= No Overlapping) and 1 (= Full overlapping) of windows
        :param window_function: Function for DFT window
        :return: short-time Fourier transform of the given signal
        """
        window = window_function(window_size)

        # hop size determines by how many samples the window is advanced
        hop_size = window_size - int(overlap_factor * window_size)

        # pad with zeros to ensure last window fits signal
        padded_samples = np.append(samples, np.zeros((len(samples) - window_size) % hop_size))
        num_frames = ((len(padded_samples) - window_size) // hop_size) + 1
        frames = [padded_samples[i*hop_size:i*hop_size+window_size] * window for i in range(num_frames)]
        return np.fft.fft(frames)

def stft(sig, frame_size, overlap_fac=0.5, window=np.hanning):
    """ short time fourier transform of audio signal """
    win = window(frame_size)
    hop_size = int(frame_size - np.floor(overlap_fac * frame_size))

    # zeros at beginning (thus center of 1st window should be for sample nr. 0)
    samples = np.append(np.zeros(np.floor(frame_size / 2.0)), sig)
    # cols for windowing
    cols = np.ceil((len(samples) - frame_size) / float(hop_size)) + 1
    # zeros at end (thus samples can be fully covered by frames)
    samples = np.append(samples, np.zeros(frame_size))

    frames = stride_tricks.as_strided(
        samples,
        shape=(cols, frame_size),
        strides=(
            samples.strides[0] * hop_size,
            samples.strides[0]
        )
    ).copy()

    frames *= win

    return np.fft.rfft(frames)

def __init__(self, configs, chunks, chunksize, channels, rate):
        self.configs = configs
        self.channels = channels
        self.chunksize = chunksize
        self.channel_len = chunks*chunksize
        self.fft_len = self.channel_len//2 + 1  # See numpy.fft.rfft
        self.fft_freqs_in_hertz = np.fft.rfftfreq(self.channel_len, d=1.0/rate)
        endpoint_notes = configs.settings.getmultistr('fft', 'endpoint_notes')
        self.notespace = process.generic.notespace(
            endpoint_notes[0], endpoint_notes[1],
            step=1.0/6)  # XXX
        self.window = np.hanning(self.channel_len)
        self.sensitivity = configs.settings.getfloat('fft', 'sensitivity')
        self.compute_weights(self.sensitivity)

        logger.debug("FFT length: {}".format(self.fft_len))

        # Create a pyfftw.FFTW object
        a = pyfftw.empty_aligned(
            self.channel_len, dtype='int16', n=pyfftw.simd_alignment)
        self.fft = pyfftw.builders.rfft(
            a, overwrite_input=True, threads=multiprocessing.cpu_count())

def hann(args):
    """
    window = hann(args)

    Computes a Hann window, with NumPy's function hanning(args).
    """
    return np.hanning(args)

# FUNCTIONS FOR TIME-FREQUENCY REPRESENTATION

def iFFT(Y, output_length=None, window=False):
    """ Inverse real-valued Fourier Transform

    Parameters
    ----------
    Y : array_like
       Frequency domain data [Nsignals x Nbins]
    output_length : int, optional
       Lenght of returned time-domain signal (Default: 2 x len(Y) + 1)
    win : boolean, optional
       Weights the resulting time-domain signal with a Hann

    Returns
    -------
    y : array_like
       Reconstructed time-domain signal
    """
    Y = _np.atleast_2d(Y)
    y = _np.fft.irfft(Y, n=output_length)

    if window:
        if window not in {'hann', 'hamming', 'blackman', 'kaiser'}:
            raise ValueError('Selected window must be one of hann, hamming, blackman or kaiser')
        no_of_signals, no_of_samples = y.shape

        if window == 'hann':
            window_array = _np.hanning(no_of_samples)
        elif window == 'hamming':
            window_array = _np.hamming(no_of_samples)
        elif window == 'blackman':
            window_array = _np.blackman(no_of_samples)
        elif window == 'kaiser':
            window_array = _np.kaiser(no_of_samples, 3)
        y = window_array * y
    return y