Spaces:
Runtime error
Runtime error
File size: 14,192 Bytes
12bfd03 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 |
# Copyright (c) 2019 Shigeki Karita
# 2020 Mobvoi Inc (Binbin Zhang)
# 2022 Xingchen Song ([email protected])
# 2024 Alibaba Inc (Xiang Lyu)
#
# 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.
"""Multi-Head Attention layer definition."""
import math
from typing import Tuple
import torch
from torch import nn
class MultiHeadedAttention(nn.Module):
"""Multi-Head Attention layer.
Args:
n_head (int): The number of heads.
n_feat (int): The number of features.
dropout_rate (float): Dropout rate.
"""
def __init__(self,
n_head: int,
n_feat: int,
dropout_rate: float,
key_bias: bool = True):
"""Construct an MultiHeadedAttention object."""
super().__init__()
assert n_feat % n_head == 0
# We assume d_v always equals d_k
self.d_k = n_feat // n_head
self.h = n_head
self.linear_q = nn.Linear(n_feat, n_feat)
self.linear_k = nn.Linear(n_feat, n_feat, bias=key_bias)
self.linear_v = nn.Linear(n_feat, n_feat)
self.linear_out = nn.Linear(n_feat, n_feat)
self.dropout = nn.Dropout(p=dropout_rate)
def forward_qkv(
self, query: torch.Tensor, key: torch.Tensor, value: torch.Tensor
) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
"""Transform query, key and value.
Args:
query (torch.Tensor): Query tensor (#batch, time1, size).
key (torch.Tensor): Key tensor (#batch, time2, size).
value (torch.Tensor): Value tensor (#batch, time2, size).
Returns:
torch.Tensor: Transformed query tensor, size
(#batch, n_head, time1, d_k).
torch.Tensor: Transformed key tensor, size
(#batch, n_head, time2, d_k).
torch.Tensor: Transformed value tensor, size
(#batch, n_head, time2, d_k).
"""
n_batch = query.size(0)
q = self.linear_q(query).view(n_batch, -1, self.h, self.d_k)
k = self.linear_k(key).view(n_batch, -1, self.h, self.d_k)
v = self.linear_v(value).view(n_batch, -1, self.h, self.d_k)
q = q.transpose(1, 2) # (batch, head, time1, d_k)
k = k.transpose(1, 2) # (batch, head, time2, d_k)
v = v.transpose(1, 2) # (batch, head, time2, d_k)
return q, k, v
def forward_attention(
self,
value: torch.Tensor,
scores: torch.Tensor,
mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool)
) -> torch.Tensor:
"""Compute attention context vector.
Args:
value (torch.Tensor): Transformed value, size
(#batch, n_head, time2, d_k).
scores (torch.Tensor): Attention score, size
(#batch, n_head, time1, time2).
mask (torch.Tensor): Mask, size (#batch, 1, time2) or
(#batch, time1, time2), (0, 0, 0) means fake mask.
Returns:
torch.Tensor: Transformed value (#batch, time1, d_model)
weighted by the attention score (#batch, time1, time2).
"""
n_batch = value.size(0)
# NOTE(xcsong): When will `if mask.size(2) > 0` be True?
# 1. onnx(16/4) [WHY? Because we feed real cache & real mask for the
# 1st chunk to ease the onnx export.]
# 2. pytorch training
if mask.size(2) > 0: # time2 > 0
mask = mask.unsqueeze(1).eq(0) # (batch, 1, *, time2)
# For last chunk, time2 might be larger than scores.size(-1)
mask = mask[:, :, :, :scores.size(-1)] # (batch, 1, *, time2)
scores = scores.masked_fill(mask, -float('inf'))
attn = torch.softmax(scores, dim=-1).masked_fill(
mask, 0.0) # (batch, head, time1, time2)
# NOTE(xcsong): When will `if mask.size(2) > 0` be False?
# 1. onnx(16/-1, -1/-1, 16/0)
# 2. jit (16/-1, -1/-1, 16/0, 16/4)
else:
attn = torch.softmax(scores, dim=-1) # (batch, head, time1, time2)
p_attn = self.dropout(attn)
x = torch.matmul(p_attn, value) # (batch, head, time1, d_k)
x = (x.transpose(1, 2).contiguous().view(n_batch, -1,
self.h * self.d_k)
) # (batch, time1, d_model)
return self.linear_out(x) # (batch, time1, d_model)
def forward(
self,
query: torch.Tensor,
key: torch.Tensor,
value: torch.Tensor,
mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
pos_emb: torch.Tensor = torch.empty(0),
cache: torch.Tensor = torch.zeros((0, 0, 0, 0))
) -> Tuple[torch.Tensor, torch.Tensor]:
"""Compute scaled dot product attention.
Args:
query (torch.Tensor): Query tensor (#batch, time1, size).
key (torch.Tensor): Key tensor (#batch, time2, size).
value (torch.Tensor): Value tensor (#batch, time2, size).
mask (torch.Tensor): Mask tensor (#batch, 1, time2) or
(#batch, time1, time2).
1.When applying cross attention between decoder and encoder,
the batch padding mask for input is in (#batch, 1, T) shape.
2.When applying self attention of encoder,
the mask is in (#batch, T, T) shape.
3.When applying self attention of decoder,
the mask is in (#batch, L, L) shape.
4.If the different position in decoder see different block
of the encoder, such as Mocha, the passed in mask could be
in (#batch, L, T) shape. But there is no such case in current
Wenet.
cache (torch.Tensor): Cache tensor (1, head, cache_t, d_k * 2),
where `cache_t == chunk_size * num_decoding_left_chunks`
and `head * d_k == size`
Returns:
torch.Tensor: Output tensor (#batch, time1, d_model).
torch.Tensor: Cache tensor (1, head, cache_t + time1, d_k * 2)
where `cache_t == chunk_size * num_decoding_left_chunks`
and `head * d_k == size`
"""
q, k, v = self.forward_qkv(query, key, value)
# NOTE(xcsong):
# when export onnx model, for 1st chunk, we feed
# cache(1, head, 0, d_k * 2) (16/-1, -1/-1, 16/0 mode)
# or cache(1, head, real_cache_t, d_k * 2) (16/4 mode).
# In all modes, `if cache.size(0) > 0` will alwayse be `True`
# and we will always do splitting and
# concatnation(this will simplify onnx export). Note that
# it's OK to concat & split zero-shaped tensors(see code below).
# when export jit model, for 1st chunk, we always feed
# cache(0, 0, 0, 0) since jit supports dynamic if-branch.
# >>> a = torch.ones((1, 2, 0, 4))
# >>> b = torch.ones((1, 2, 3, 4))
# >>> c = torch.cat((a, b), dim=2)
# >>> torch.equal(b, c) # True
# >>> d = torch.split(a, 2, dim=-1)
# >>> torch.equal(d[0], d[1]) # True
if cache.size(0) > 0:
key_cache, value_cache = torch.split(cache,
cache.size(-1) // 2,
dim=-1)
k = torch.cat([key_cache, k], dim=2)
v = torch.cat([value_cache, v], dim=2)
# NOTE(xcsong): We do cache slicing in encoder.forward_chunk, since it's
# non-trivial to calculate `next_cache_start` here.
new_cache = torch.cat((k, v), dim=-1)
scores = torch.matmul(q, k.transpose(-2, -1)) / math.sqrt(self.d_k)
return self.forward_attention(v, scores, mask), new_cache
class RelPositionMultiHeadedAttention(MultiHeadedAttention):
"""Multi-Head Attention layer with relative position encoding.
Paper: https://arxiv.org/abs/1901.02860
Args:
n_head (int): The number of heads.
n_feat (int): The number of features.
dropout_rate (float): Dropout rate.
"""
def __init__(self,
n_head: int,
n_feat: int,
dropout_rate: float,
key_bias: bool = True):
"""Construct an RelPositionMultiHeadedAttention object."""
super().__init__(n_head, n_feat, dropout_rate, key_bias)
# linear transformation for positional encoding
self.linear_pos = nn.Linear(n_feat, n_feat, bias=False)
# these two learnable bias are used in matrix c and matrix d
# as described in https://arxiv.org/abs/1901.02860 Section 3.3
self.pos_bias_u = nn.Parameter(torch.Tensor(self.h, self.d_k))
self.pos_bias_v = nn.Parameter(torch.Tensor(self.h, self.d_k))
torch.nn.init.xavier_uniform_(self.pos_bias_u)
torch.nn.init.xavier_uniform_(self.pos_bias_v)
def rel_shift(self, x):
"""Compute relative positional encoding.
Args:
x (torch.Tensor): Input tensor (batch, head, time1, 2*time1-1).
time1 means the length of query vector.
Returns:
torch.Tensor: Output tensor.
"""
zero_pad = torch.zeros((*x.size()[:3], 1), device=x.device, dtype=x.dtype)
x_padded = torch.cat([zero_pad, x], dim=-1)
x_padded = x_padded.view(*x.size()[:2], x.size(3) + 1, x.size(2))
x = x_padded[:, :, 1:].view_as(x)[
:, :, :, : x.size(-1) // 2 + 1
] # only keep the positions from 0 to time2
return x
def forward(
self,
query: torch.Tensor,
key: torch.Tensor,
value: torch.Tensor,
mask: torch.Tensor = torch.ones((0, 0, 0), dtype=torch.bool),
pos_emb: torch.Tensor = torch.empty(0),
cache: torch.Tensor = torch.zeros((0, 0, 0, 0))
) -> Tuple[torch.Tensor, torch.Tensor]:
"""Compute 'Scaled Dot Product Attention' with rel. positional encoding.
Args:
query (torch.Tensor): Query tensor (#batch, time1, size).
key (torch.Tensor): Key tensor (#batch, time2, size).
value (torch.Tensor): Value tensor (#batch, time2, size).
mask (torch.Tensor): Mask tensor (#batch, 1, time2) or
(#batch, time1, time2), (0, 0, 0) means fake mask.
pos_emb (torch.Tensor): Positional embedding tensor
(#batch, time2, size).
cache (torch.Tensor): Cache tensor (1, head, cache_t, d_k * 2),
where `cache_t == chunk_size * num_decoding_left_chunks`
and `head * d_k == size`
Returns:
torch.Tensor: Output tensor (#batch, time1, d_model).
torch.Tensor: Cache tensor (1, head, cache_t + time1, d_k * 2)
where `cache_t == chunk_size * num_decoding_left_chunks`
and `head * d_k == size`
"""
q, k, v = self.forward_qkv(query, key, value)
q = q.transpose(1, 2) # (batch, time1, head, d_k)
# NOTE(xcsong):
# when export onnx model, for 1st chunk, we feed
# cache(1, head, 0, d_k * 2) (16/-1, -1/-1, 16/0 mode)
# or cache(1, head, real_cache_t, d_k * 2) (16/4 mode).
# In all modes, `if cache.size(0) > 0` will alwayse be `True`
# and we will always do splitting and
# concatnation(this will simplify onnx export). Note that
# it's OK to concat & split zero-shaped tensors(see code below).
# when export jit model, for 1st chunk, we always feed
# cache(0, 0, 0, 0) since jit supports dynamic if-branch.
# >>> a = torch.ones((1, 2, 0, 4))
# >>> b = torch.ones((1, 2, 3, 4))
# >>> c = torch.cat((a, b), dim=2)
# >>> torch.equal(b, c) # True
# >>> d = torch.split(a, 2, dim=-1)
# >>> torch.equal(d[0], d[1]) # True
if cache.size(0) > 0:
key_cache, value_cache = torch.split(cache,
cache.size(-1) // 2,
dim=-1)
k = torch.cat([key_cache, k], dim=2)
v = torch.cat([value_cache, v], dim=2)
# NOTE(xcsong): We do cache slicing in encoder.forward_chunk, since it's
# non-trivial to calculate `next_cache_start` here.
new_cache = torch.cat((k, v), dim=-1)
n_batch_pos = pos_emb.size(0)
p = self.linear_pos(pos_emb).view(n_batch_pos, -1, self.h, self.d_k)
p = p.transpose(1, 2) # (batch, head, time1, d_k)
# (batch, head, time1, d_k)
q_with_bias_u = (q + self.pos_bias_u).transpose(1, 2)
# (batch, head, time1, d_k)
q_with_bias_v = (q + self.pos_bias_v).transpose(1, 2)
# compute attention score
# first compute matrix a and matrix c
# as described in https://arxiv.org/abs/1901.02860 Section 3.3
# (batch, head, time1, time2)
matrix_ac = torch.matmul(q_with_bias_u, k.transpose(-2, -1))
# compute matrix b and matrix d
# (batch, head, time1, time2)
matrix_bd = torch.matmul(q_with_bias_v, p.transpose(-2, -1))
# NOTE(Xiang Lyu): Keep rel_shift since espnet rel_pos_emb is used
if matrix_ac.shape != matrix_bd.shape:
matrix_bd = self.rel_shift(matrix_bd)
scores = (matrix_ac + matrix_bd) / math.sqrt(
self.d_k) # (batch, head, time1, time2)
return self.forward_attention(v, scores, mask), new_cache
|