# Copyright (c) 2021 PaddlePaddle 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.
# Modified from espnet(https://github.com/espnet/espnet)
"""Encoder self-attention layer definition."""
import paddle
from paddle import nn
from paddlespeech.t2s.modules.layer_norm import LayerNorm
class EncoderLayer(nn.Layer):
"""Encoder layer module.
Parameters
----------
size : int
Input dimension.
self_attn : nn.Layer
Self-attention module instance.
`MultiHeadedAttention` or `RelPositionMultiHeadedAttention` instance
can be used as the argument.
feed_forward : nn.Layer
Feed-forward module instance.
`PositionwiseFeedForward`, `MultiLayeredConv1d`, or `Conv1dLinear` instance
can be used as the argument.
feed_forward_macaron : nn.Layer
Additional feed-forward module instance.
`PositionwiseFeedForward`, `MultiLayeredConv1d`, or `Conv1dLinear` instance
can be used as the argument.
conv_module : nn.Layer
Convolution module instance.
`ConvlutionModule` instance can be used as the argument.
dropout_rate : float
Dropout rate.
normalize_before : bool
Whether to use layer_norm before the first block.
concat_after : bool
Whether to concat attention layer's input and output.
if True, additional linear will be applied.
i.e. x -> x + linear(concat(x, att(x)))
if False, no additional linear will be applied. i.e. x -> x + att(x)
stochastic_depth_rate : float
Proability to skip this layer.
During training, the layer may skip residual computation and return input
as-is with given probability.
"""
def __init__(
self,
size,
self_attn,
feed_forward,
feed_forward_macaron,
conv_module,
dropout_rate,
normalize_before=True,
concat_after=False,
stochastic_depth_rate=0.0, ):
"""Construct an EncoderLayer object."""
super().__init__()
self.self_attn = self_attn
self.feed_forward = feed_forward
self.feed_forward_macaron = feed_forward_macaron
self.conv_module = conv_module
self.norm_ff = LayerNorm(size) # for the FNN module
self.norm_mha = LayerNorm(size) # for the MHA module
if feed_forward_macaron is not None:
self.norm_ff_macaron = LayerNorm(size)
self.ff_scale = 0.5
else:
self.ff_scale = 1.0
if self.conv_module is not None:
self.norm_conv = LayerNorm(size) # for the CNN module
self.norm_final = LayerNorm(
size) # for the final output of the block
self.dropout = nn.Dropout(dropout_rate)
self.size = size
self.normalize_before = normalize_before
self.concat_after = concat_after
if self.concat_after:
self.concat_linear = nn.Linear(size + size, size)
self.stochastic_depth_rate = stochastic_depth_rate
def forward(self, x_input, mask, cache=None):
"""Compute encoded features.
Parameters
----------
x_input : Union[Tuple, paddle.Tensor]
Input tensor w/ or w/o pos emb.
- w/ pos emb: Tuple of tensors [(#batch, time, size), (1, time, size)].
- w/o pos emb: Tensor (#batch, time, size).
mask : paddle.Tensor
Mask tensor for the input (#batch, time).
cache paddle.Tensor
Cache tensor of the input (#batch, time - 1, size).
Returns
----------
paddle.Tensor
Output tensor (#batch, time, size).
paddle.Tensor
Mask tensor (#batch, time).
"""
if isinstance(x_input, tuple):
x, pos_emb = x_input[0], x_input[1]
else:
x, pos_emb = x_input, None
skip_layer = False
# with stochastic depth, residual connection `x + f(x)` becomes
# `x <- x + 1 / (1 - p) * f(x)` at training time.
stoch_layer_coeff = 1.0
if self.training and self.stochastic_depth_rate > 0:
skip_layer = paddle.rand(1).item() < self.stochastic_depth_rate
stoch_layer_coeff = 1.0 / (1 - self.stochastic_depth_rate)
if skip_layer:
if cache is not None:
x = paddle.concat([cache, x], axis=1)
if pos_emb is not None:
return (x, pos_emb), mask
return x, mask
# whether to use macaron style
if self.feed_forward_macaron is not None:
residual = x
if self.normalize_before:
x = self.norm_ff_macaron(x)
x = residual + stoch_layer_coeff * self.ff_scale * self.dropout(
self.feed_forward_macaron(x))
if not self.normalize_before:
x = self.norm_ff_macaron(x)
# multi-headed self-attention module
residual = x
if self.normalize_before:
x = self.norm_mha(x)
if cache is None:
x_q = x
else:
assert cache.shape == (x.shape[0], x.shape[1] - 1, self.size)
x_q = x[:, -1:, :]
residual = residual[:, -1:, :]
mask = None if mask is None else mask[:, -1:, :]
if pos_emb is not None:
x_att = self.self_attn(x_q, x, x, pos_emb, mask)
else:
x_att = self.self_attn(x_q, x, x, mask)
if self.concat_after:
x_concat = paddle.concat((x, x_att), axis=-1)
x = residual + stoch_layer_coeff * self.concat_linear(x_concat)
else:
x = residual + stoch_layer_coeff * self.dropout(x_att)
if not self.normalize_before:
x = self.norm_mha(x)
# convolution module
if self.conv_module is not None:
residual = x
if self.normalize_before:
x = self.norm_conv(x)
x = residual + stoch_layer_coeff * self.dropout(self.conv_module(x))
if not self.normalize_before:
x = self.norm_conv(x)
# feed forward module
residual = x
if self.normalize_before:
x = self.norm_ff(x)
x = residual + stoch_layer_coeff * self.ff_scale * self.dropout(
self.feed_forward(x))
if not self.normalize_before:
x = self.norm_ff(x)
if self.conv_module is not None:
x = self.norm_final(x)
if cache is not None:
x = paddle.concat([cache, x], axis=1)
if pos_emb is not None:
return (x, pos_emb), mask
return x, mask