Tacotron2

An implementation of Tacotron2 (excluding WaveNet-vocoder) in TensorFlow.

2018-01-30 incompleted,

.models , .utils , hparams.py , train.py

2018-02-04 incompleted,

.tacotron2

2018-02-05 incompleted,

.tacotron2-18.02.05

2018-02-06 complete !

.tacotron2-18.02.06

Attentions:

/tacotron2-18.02.06/attentions.py

There are two styles of attention-mechanism. (1.LocationBasedAttention, 2.HybridAttention)

1.LocationBasedAttention

Calculate the score using (query, alignments).

score = tf.reduce_sum(self.v * tf.tanh(processed_query + location_f), [2])

2.HybridAttention

Calculate the score using (processed-memory, query, alignments)

score = tf.reduce_sum(self.v * tf.tanh(self.keys + processed_query + location_f), [2])

MyAttentionWrapper:

/tacotron2-18.02.06/attention_wrapper.py

Wrapping attention with LSTMs directly, not with such a 'prenet wrapper'.

So there are 6 steps

• Step 1: Passed through a 'Pre-net'.

"The prediction from the previous time step is first passed through a small "pre-net" contatining 2 fully connected layers of 256 hidden ReLU units."

inputs = dec_prenet(inputs, hp.dec_prenet_sizes, scope='decoder_prenet_layer')

• Step 2: Mix the inputs and previous step's attention output via cell_input_fn.

"The pre-net output and attention context vector are concatenated and ..."

cell_inputs = self._cell_input_fn(inputs, state.attention)

• Step 3: Call the wrapped cell with this input and its previous state.

"...and passed through a stack of 2 uni-directional LSTM layers with 1024 units."

LSTM_output, next_cell_state = self._cell(cell_inputs, state.cell_state)

• Step 4: Concat 'LSTM_output' with 'context_vector(attention)'

"The concatenation of the LSTM output and the attention context vector is then..."

concat_output_LSTM = tf.concat([LSTM_output, state.attention], axis=-1)

• Step 5: Concatted output projected through linear-transform.

"...then projected through a linear transform to produce a prediction of the target spectrogram frame."

cell_output = projection(concat_output_LSTM, hp.num_mels, scope='decoder_projection_layer')

• Step 6: Calculate the score, alignments and attention.

    attention, alignments = _compute_attention(attention_mechanism, cell_output, previous_alignments[i],  self._attention_layers[i] if self._attention_layers else None)
  

So many references from https://github.com/Rayhane-mamah/Tacotron-2