text: # Copyright 2017 The TensorFlow Authors All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # ==============================================================================
  
  """Global parameters for the VGGish model.
  
  See vggish_slim.py for more information.
  """
  
  # Architectural constants.
  NUM_FRAMES = 96  # Frames in input mel-spectrogram patch.
  NUM_BANDS = 64  # Frequency bands in input mel-spectrogram patch.
  EMBEDDING_SIZE = 128  # Size of embedding layer.
  
  # Hyperparameters used in feature and example generation.
  SAMPLE_RATE = 16000
  STFT_WINDOW_LENGTH_SECONDS = 0.025
  STFT_HOP_LENGTH_SECONDS = 0.010
  NUM_MEL_BINS = NUM_BANDS
  MEL_MIN_HZ = 125
  MEL_MAX_HZ = 7500
  LOG_OFFSET = 0.01  # Offset used for stabilized log of input mel-spectrogram.
  EXAMPLE_WINDOW_SECONDS = 0.96  # Each example contains 96 10ms frames
  EXAMPLE_HOP_SECONDS = 0.96     # with zero overlap.
  
  # Parameters used for embedding postprocessing.
  PCA_EIGEN_VECTORS_NAME = 'pca_eigen_vectors'
  PCA_MEANS_NAME = 'pca_means'
  QUANTIZE_MIN_VAL = -2.0
  QUANTIZE_MAX_VAL = +2.0
  
  # Hyperparameters used in training.
  INIT_STDDEV = 0.01  # Standard deviation used to initialize weights.
  LEARNING_RATE = 1e-4  # Learning rate for the Adam optimizer.
  ADAM_EPSILON = 1e-8  # Epsilon for the Adam optimizer.
  
  # Names of ops, tensors, and features.
  INPUT_OP_NAME = 'vggish/input_features'
  INPUT_TENSOR_NAME = INPUT_OP_NAME + ':0'
  OUTPUT_OP_NAME = 'vggish/embedding'
  #OUTPUT_OP_NAME = 'vggish/conv1'
  OUTPUT_TENSOR_NAME = OUTPUT_OP_NAME + ':0'
  AUDIO_EMBEDDING_FEATURE_NAME = 'audio_embedding'
  