code: def add_delta_deltas(filterbanks, name=None):
      """Compute time first and second-order derivative channels.
  
      Args:
        filterbanks: float32 tensor with shape [batch_size, len, num_bins, 1]
        name: scope name
  
      Returns:
        float32 tensor with shape [batch_size, len, num_bins, 3]
      """
      delta_filter = np.array([2, 1, 0, -1, -2])
      delta_delta_filter = scipy.signal.convolve(
          delta_filter, delta_filter, "full"
      )
  
      delta_filter_stack = np.array(
          [
              [0] * 4 + [1] + [0] * 4,
              [0] * 2 + list(delta_filter) + [0] * 2,
              list(delta_delta_filter),
          ],
          dtype=np.float32,
      ).T[:, None, None, :]
  
      delta_filter_stack /= np.sqrt(
          np.sum(delta_filter_stack**2, axis=0, keepdims=True)
      )
  
      filterbanks = tf.nn.conv2d(
          filterbanks,
          delta_filter_stack,
          [1, 1, 1, 1],
          "SAME",
          data_format="NHWC",
          name=name,
      )
      return filterbanks
  
file_path: tensor2tensor/tensor2tensor/layers/common_audio.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import functools
  import numpy
  import scipy.signal
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling a global function with example usage: add_delta_deltas(filterbanks, name) and returns: filterbanks