hll.py 文件源码

def _compute_cqt(self, y, sr):
        """Compute a CQT.

        Parameters
        ----------
        y : np.array
            Audio signal
        sr : float
            Audio singal sample rate

        Returns
        -------
        cqt_log : np.array [n_samples, n_freqs]
            Log amplitude CQT.
        samples : np.array [n_samples]
            CQT time stamps.
        freqs : np.array [n_freqs]
            CQT frequencies.

        """
        fmin = librosa.note_to_hz(self.min_note)
        bins_per_octave = 12
        n_cqt_bins = bins_per_octave * self.n_octaves
        cqt = np.abs(librosa.cqt(
            y, sr=sr, hop_length=self.hop_size, fmin=fmin,
            filter_scale=self.filter_scale,
            bins_per_octave=bins_per_octave, n_bins=n_cqt_bins
        ))

        cqt = self._norm_matrix(cqt)

        n_time_frames = cqt.shape[1]

        freqs = librosa.cqt_frequencies(
            fmin=fmin, bins_per_octave=bins_per_octave,
            n_bins=n_cqt_bins
        )
        samples = librosa.frames_to_samples(
            range(n_time_frames), hop_length=self.hop_size
        )

        return cqt, samples, freqs