librosa/core/constantq.py
def __cqt_filter_fft(sr, fmin, n_bins, bins_per_octave, tuning,
                     filter_scale, norm, sparsity, hop_length=None,
                     window='hann'):
    '''Generate the frequency domain constant-Q filter basis.'''

    basis, lengths = filters.constant_q(sr,
                                        fmin=fmin,
                                        n_bins=n_bins,
                                        bins_per_octave=bins_per_octave,
                                        tuning=tuning,
                                        filter_scale=filter_scale,
                                        norm=norm,
                                        pad_fft=True,
                                        window=window)

    # Filters are padded up to the nearest integral power of 2
    n_fft = basis.shape[1]

    if (hop_length is not None and
            n_fft < 2.0**(1 + np.ceil(np.log2(hop_length)))):

        n_fft = int(2.0 ** (1 + np.ceil(np.log2(hop_length))))

    # re-normalize bases with respect to the FFT window length
    basis *= lengths[:, np.newaxis] / float(n_fft)

    # FFT and retain only the non-negative frequencies
    fft = get_fftlib()
    fft_basis = fft.fft(basis, n=n_fft, axis=1)[:, :(n_fft // 2)+1]

    # sparsify the basis
    fft_basis = util.sparsify_rows(fft_basis, quantile=sparsity)

    return fft_basis, n_fft, lengths
def __cqt_filter_fft(sr, fmin, n_bins, bins_per_octave, tuning,
                     filter_scale, norm, sparsity, hop_length=None,
                     window='hann'):
    '''Generate the frequency domain constant-Q filter basis.'''

    basis, lengths = filters.constant_q(sr,
                                        fmin=fmin,
                                        n_bins=n_bins,
                                        bins_per_octave=bins_per_octave,
                                        tuning=tuning,
                                        filter_scale=filter_scale,
                                        norm=norm,
                                        pad_fft=True,
                                        window=window)

    # Filters are padded up to the nearest integral power of 2
    n_fft = basis.shape[1]

    if (hop_length is not None and
            n_fft < 2.0**(1 + np.ceil(np.log2(hop_length)))):

        n_fft = int(2.0 ** (1 + np.ceil(np.log2(hop_length))))

    # re-normalize bases with respect to the FFT window length
    basis *= lengths[:, np.newaxis] / float(n_fft)

    # FFT and retain only the non-negative frequencies
    fft = get_fftlib()
    fft_basis = fft.fft(basis, n=n_fft, axis=1)[:, :(n_fft // 2)+1]

    # sparsify the basis
    fft_basis = util.sparsify_rows(fft_basis, quantile=sparsity)

    return fft_basis, n_fft, lengths
Generate the frequency domain constant-Q filter basis.