class_docstr: Helper functions to compute specgrams.
class_docstr_tok: ["Helper","functions","to","compute","specgrams","."]
docstr: Get the mel transformation matrix.
docstr_tok: ["Get","the","mel","transformation","matrix","."]
code: def _linear_to_mel_matrix(self):
      """Get the mel transformation matrix."""
      num_freq_bins = self._nfft // 2
      lower_edge_hertz = 0.0
      upper_edge_hertz = self._sample_rate / 2.0
      num_mel_bins = num_freq_bins // self._mel_downscale
      return spectral_ops.linear_to_mel_weight_matrix(
          num_mel_bins,
          num_freq_bins,
          self._sample_rate,
          lower_edge_hertz,
          upper_edge_hertz,
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from magenta.models.gansynth.lib import spectral_ops
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 9 for calling the SpecgramsHelper obj's underlying member method code with example usage: obj._linear_to_mel_matrix() and returns: spectral_ops