code: def apply_local_cmvn(feats, epsilon=1e-9):
      """feats: (NHWC)"""
      mean = tf.expand_dims(keras_backend.mean(feats, axis=1), axis=1)
      var = tf.expand_dims(keras_backend.var(feats, axis=1), axis=1)
      feats = (feats - mean) * tf.rsqrt(var + epsilon)
      return feats
  
file_path: delta/delta/utils/cmvn.py
imports: import numpy
  import delta.compat
  from tensorflow.python.keras import backend
label_desc: Use image node_id 6 for calling a global function with example usage: apply_local_cmvn(feats, epsilon) and returns: feats