Source code for torchaudio.prototype.models.conv_emformer
import math
from typing import List, Optional, Tuple
import torch
from torchaudio.models.emformer import _EmformerAttention, _EmformerImpl, _get_weight_init_gains
def _get_activation_module(activation: str) -> torch.nn.Module:
if activation == "relu":
return torch.nn.ReLU()
elif activation == "gelu":
return torch.nn.GELU()
elif activation == "silu":
return torch.nn.SiLU()
else:
raise ValueError(f"Unsupported activation {activation}")
class _ResidualContainer(torch.nn.Module):
def __init__(self, module: torch.nn.Module, output_weight: int):
super().__init__()
self.module = module
self.output_weight = output_weight
def forward(self, input: torch.Tensor):
output = self.module(input)
return output * self.output_weight + input
class _ConvolutionModule(torch.nn.Module):
def __init__(
self,
input_dim: int,
segment_length: int,
right_context_length: int,
kernel_size: int,
activation: str = "silu",
dropout: float = 0.0,
):
super().__init__()
self.input_dim = input_dim
self.segment_length = segment_length
self.right_context_length = right_context_length
self.state_size = kernel_size - 1
self.pre_conv = torch.nn.Sequential(
torch.nn.LayerNorm(input_dim), torch.nn.Linear(input_dim, 2 * input_dim, bias=True), torch.nn.GLU()
)
self.conv = torch.nn.Conv1d(
in_channels=input_dim,
out_channels=input_dim,
kernel_size=kernel_size,
stride=1,
padding=0,
groups=input_dim,
)
self.post_conv = torch.nn.Sequential(
torch.nn.LayerNorm(input_dim),
_get_activation_module(activation),
torch.nn.Linear(input_dim, input_dim, bias=True),
torch.nn.Dropout(p=dropout),
)
def _split_right_context(self, utterance: torch.Tensor, right_context: torch.Tensor) -> torch.Tensor:
T, B, D = right_context.size()
if T % self.right_context_length != 0:
raise ValueError("Tensor length should be divisible by its right context length")
num_segments = T // self.right_context_length
# (num_segments, right context length, B, D)
right_context_segments = right_context.reshape(num_segments, self.right_context_length, B, D)
right_context_segments = right_context_segments.permute(0, 2, 1, 3).reshape(
num_segments * B, self.right_context_length, D
)
pad_segments = [] # [(kernel_size - 1, B, D), ...]
for seg_idx in range(num_segments):
end_idx = min(self.state_size + (seg_idx + 1) * self.segment_length, utterance.size(0))
start_idx = end_idx - self.state_size
pad_segments.append(utterance[start_idx:end_idx, :, :])
pad_segments = torch.cat(pad_segments, dim=1).permute(1, 0, 2) # (num_segments * B, kernel_size - 1, D)
return torch.cat([pad_segments, right_context_segments], dim=1).permute(0, 2, 1)
def _merge_right_context(self, right_context: torch.Tensor, B: int) -> torch.Tensor:
# (num_segments * B, D, right_context_length)
right_context = right_context.reshape(-1, B, self.input_dim, self.right_context_length)
right_context = right_context.permute(0, 3, 1, 2)
return right_context.reshape(-1, B, self.input_dim) # (right_context_length * num_segments, B, D)
def forward(
self, utterance: torch.Tensor, right_context: torch.Tensor, state: Optional[torch.Tensor]
) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
input = torch.cat((right_context, utterance)) # input: (T, B, D)
x = self.pre_conv(input)
x_right_context, x_utterance = x[: right_context.size(0), :, :], x[right_context.size(0) :, :, :]
x_utterance = x_utterance.permute(1, 2, 0) # (B, D, T_utterance)
if state is None:
state = torch.zeros(
input.size(1),
input.size(2),
self.state_size,
device=input.device,
dtype=input.dtype,
) # (B, D, T)
state_x_utterance = torch.cat([state, x_utterance], dim=2)
conv_utterance = self.conv(state_x_utterance) # (B, D, T_utterance)
conv_utterance = conv_utterance.permute(2, 0, 1)
if self.right_context_length > 0:
# (B * num_segments, D, right_context_length + kernel_size - 1)
right_context_block = self._split_right_context(state_x_utterance.permute(2, 0, 1), x_right_context)
conv_right_context_block = self.conv(right_context_block) # (B * num_segments, D, right_context_length)
# (T_right_context, B, D)
conv_right_context = self._merge_right_context(conv_right_context_block, input.size(1))
y = torch.cat([conv_right_context, conv_utterance], dim=0)
else:
y = conv_utterance
output = self.post_conv(y) + input
new_state = state_x_utterance[:, :, -self.state_size :]
return output[right_context.size(0) :], output[: right_context.size(0)], new_state
def infer(
self, utterance: torch.Tensor, right_context: torch.Tensor, state: Optional[torch.Tensor]
) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
input = torch.cat((utterance, right_context))
x = self.pre_conv(input) # (T, B, D)
x = x.permute(1, 2, 0) # (B, D, T)
if state is None:
state = torch.zeros(
input.size(1),
input.size(2),
self.state_size,
device=input.device,
dtype=input.dtype,
) # (B, D, T)
state_x = torch.cat([state, x], dim=2)
conv_out = self.conv(state_x)
conv_out = conv_out.permute(2, 0, 1) # T, B, D
output = self.post_conv(conv_out) + input
new_state = state_x[:, :, -self.state_size - right_context.size(0) : -right_context.size(0)]
return output[: utterance.size(0)], output[utterance.size(0) :], new_state
class _ConvEmformerLayer(torch.nn.Module):
r"""Convolution-augmented Emformer layer that constitutes ConvEmformer.
Args:
input_dim (int): input dimension.
num_heads (int): number of attention heads.
ffn_dim: (int): hidden layer dimension of feedforward network.
segment_length (int): length of each input segment.
kernel_size (int): size of kernel to use in convolution module.
dropout (float, optional): dropout probability. (Default: 0.0)
ffn_activation (str, optional): activation function to use in feedforward network.
Must be one of ("relu", "gelu", "silu"). (Default: "relu")
left_context_length (int, optional): length of left context. (Default: 0)
right_context_length (int, optional): length of right context. (Default: 0)
max_memory_size (int, optional): maximum number of memory elements to use. (Default: 0)
weight_init_gain (float or None, optional): scale factor to apply when initializing
attention module parameters. (Default: ``None``)
tanh_on_mem (bool, optional): if ``True``, applies tanh to memory elements. (Default: ``False``)
negative_inf (float, optional): value to use for negative infinity in attention weights. (Default: -1e8)
conv_activation (str, optional): activation function to use in convolution module.
Must be one of ("relu", "gelu", "silu"). (Default: "silu")
"""
def __init__(
self,
input_dim: int,
num_heads: int,
ffn_dim: int,
segment_length: int,
kernel_size: int,
dropout: float = 0.0,
ffn_activation: str = "relu",
left_context_length: int = 0,
right_context_length: int = 0,
max_memory_size: int = 0,
weight_init_gain: Optional[float] = None,
tanh_on_mem: bool = False,
negative_inf: float = -1e8,
conv_activation: str = "silu",
):
super().__init__()
# TODO: implement talking heads attention.
self.attention = _EmformerAttention(
input_dim=input_dim,
num_heads=num_heads,
dropout=dropout,
weight_init_gain=weight_init_gain,
tanh_on_mem=tanh_on_mem,
negative_inf=negative_inf,
)
self.dropout = torch.nn.Dropout(dropout)
self.memory_op = torch.nn.AvgPool1d(kernel_size=segment_length, stride=segment_length, ceil_mode=True)
activation_module = _get_activation_module(ffn_activation)
self.ffn0 = _ResidualContainer(
torch.nn.Sequential(
torch.nn.LayerNorm(input_dim),
torch.nn.Linear(input_dim, ffn_dim),
activation_module,
torch.nn.Dropout(dropout),
torch.nn.Linear(ffn_dim, input_dim),
torch.nn.Dropout(dropout),
),
0.5,
)
self.ffn1 = _ResidualContainer(
torch.nn.Sequential(
torch.nn.LayerNorm(input_dim),
torch.nn.Linear(input_dim, ffn_dim),
activation_module,
torch.nn.Dropout(dropout),
torch.nn.Linear(ffn_dim, input_dim),
torch.nn.Dropout(dropout),
),
0.5,
)
self.layer_norm_input = torch.nn.LayerNorm(input_dim)
self.layer_norm_output = torch.nn.LayerNorm(input_dim)
self.conv = _ConvolutionModule(
input_dim=input_dim,
kernel_size=kernel_size,
activation=conv_activation,
dropout=dropout,
segment_length=segment_length,
right_context_length=right_context_length,
)
self.left_context_length = left_context_length
self.segment_length = segment_length
self.max_memory_size = max_memory_size
self.input_dim = input_dim
self.kernel_size = kernel_size
self.use_mem = max_memory_size > 0
def _init_state(self, batch_size: int, device: Optional[torch.device]) -> List[torch.Tensor]:
empty_memory = torch.zeros(self.max_memory_size, batch_size, self.input_dim, device=device)
left_context_key = torch.zeros(self.left_context_length, batch_size, self.input_dim, device=device)
left_context_val = torch.zeros(self.left_context_length, batch_size, self.input_dim, device=device)
past_length = torch.zeros(1, batch_size, dtype=torch.int32, device=device)
conv_cache = torch.zeros(
batch_size,
self.input_dim,
self.kernel_size - 1,
device=device,
)
return [empty_memory, left_context_key, left_context_val, past_length, conv_cache]
def _unpack_state(self, state: List[torch.Tensor]) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, torch.Tensor]:
past_length = state[3][0][0].item()
past_left_context_length = min(self.left_context_length, past_length)
past_mem_length = min(self.max_memory_size, math.ceil(past_length / self.segment_length))
pre_mems = state[0][self.max_memory_size - past_mem_length :]
lc_key = state[1][self.left_context_length - past_left_context_length :]
lc_val = state[2][self.left_context_length - past_left_context_length :]
conv_cache = state[4]
return pre_mems, lc_key, lc_val, conv_cache
def _pack_state(
self,
next_k: torch.Tensor,
next_v: torch.Tensor,
update_length: int,
mems: torch.Tensor,
conv_cache: torch.Tensor,
state: List[torch.Tensor],
) -> List[torch.Tensor]:
new_k = torch.cat([state[1], next_k])
new_v = torch.cat([state[2], next_v])
state[0] = torch.cat([state[0], mems])[-self.max_memory_size :]
state[1] = new_k[new_k.shape[0] - self.left_context_length :]
state[2] = new_v[new_v.shape[0] - self.left_context_length :]
state[3] = state[3] + update_length
state[4] = conv_cache
return state
def _apply_pre_attention(
self, utterance: torch.Tensor, right_context: torch.Tensor, summary: torch.Tensor
) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, torch.Tensor]:
x = torch.cat([right_context, utterance, summary])
ffn0_out = self.ffn0(x)
layer_norm_input_out = self.layer_norm_input(ffn0_out)
layer_norm_input_right_context, layer_norm_input_utterance, layer_norm_input_summary = (
layer_norm_input_out[: right_context.size(0)],
layer_norm_input_out[right_context.size(0) : right_context.size(0) + utterance.size(0)],
layer_norm_input_out[right_context.size(0) + utterance.size(0) :],
)
return ffn0_out, layer_norm_input_right_context, layer_norm_input_utterance, layer_norm_input_summary
def _apply_post_attention(
self,
rc_output: torch.Tensor,
ffn0_out: torch.Tensor,
conv_cache: Optional[torch.Tensor],
rc_length: int,
utterance_length: int,
) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
result = self.dropout(rc_output) + ffn0_out[: rc_length + utterance_length]
conv_utterance, conv_right_context, conv_cache = self.conv(result[rc_length:], result[:rc_length], conv_cache)
result = torch.cat([conv_right_context, conv_utterance])
result = self.ffn1(result)
result = self.layer_norm_output(result)
output_utterance, output_right_context = result[rc_length:], result[:rc_length]
return output_utterance, output_right_context, conv_cache
def forward(
self,
utterance: torch.Tensor,
lengths: torch.Tensor,
right_context: torch.Tensor,
mems: torch.Tensor,
attention_mask: torch.Tensor,
) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
r"""Forward pass for training.
B: batch size;
D: feature dimension of each frame;
T: number of utterance frames;
R: number of right context frames;
M: number of memory elements.
Args:
utterance (torch.Tensor): utterance frames, with shape `(T, B, D)`.
lengths (torch.Tensor): with shape `(B,)` and i-th element representing
number of valid frames for i-th batch element in ``utterance``.
right_context (torch.Tensor): right context frames, with shape `(R, B, D)`.
mems (torch.Tensor): memory elements, with shape `(M, B, D)`.
attention_mask (torch.Tensor): attention mask for underlying attention module.
Returns:
(Tensor, Tensor, Tensor):
Tensor
encoded utterance frames, with shape `(T, B, D)`.
Tensor
updated right context frames, with shape `(R, B, D)`.
Tensor
updated memory elements, with shape `(M, B, D)`.
"""
if self.use_mem:
summary = self.memory_op(utterance.permute(1, 2, 0)).permute(2, 0, 1)
else:
summary = torch.empty(0).to(dtype=utterance.dtype, device=utterance.device)
(
ffn0_out,
layer_norm_input_right_context,
layer_norm_input_utterance,
layer_norm_input_summary,
) = self._apply_pre_attention(utterance, right_context, summary)
rc_output, output_mems = self.attention(
utterance=layer_norm_input_utterance,
lengths=lengths,
right_context=layer_norm_input_right_context,
summary=layer_norm_input_summary,
mems=mems,
attention_mask=attention_mask,
)
output_utterance, output_right_context, _ = self._apply_post_attention(
rc_output, ffn0_out, None, right_context.size(0), utterance.size(0)
)
return output_utterance, output_right_context, output_mems
@torch.jit.export
def infer(
self,
utterance: torch.Tensor,
lengths: torch.Tensor,
right_context: torch.Tensor,
state: Optional[List[torch.Tensor]],
mems: torch.Tensor,
) -> Tuple[torch.Tensor, torch.Tensor, List[torch.Tensor], torch.Tensor]:
r"""Forward pass for inference.
B: batch size;
D: feature dimension of each frame;
T: number of utterance frames;
R: number of right context frames;
M: number of memory elements.
Args:
utterance (torch.Tensor): utterance frames, with shape `(T, B, D)`.
lengths (torch.Tensor): with shape `(B,)` and i-th element representing
number of valid frames for i-th batch element in ``utterance``.
right_context (torch.Tensor): right context frames, with shape `(R, B, D)`.
state (List[torch.Tensor] or None): list of tensors representing layer internal state
generated in preceding invocation of ``infer``.
mems (torch.Tensor): memory elements, with shape `(M, B, D)`.
Returns:
(Tensor, Tensor, List[torch.Tensor], Tensor):
Tensor
encoded utterance frames, with shape `(T, B, D)`.
Tensor
updated right context frames, with shape `(R, B, D)`.
List[Tensor]
list of tensors representing layer internal state
generated in current invocation of ``infer``.
Tensor
updated memory elements, with shape `(M, B, D)`.
"""
if self.use_mem:
summary = self.memory_op(utterance.permute(1, 2, 0)).permute(2, 0, 1)[:1]
else:
summary = torch.empty(0).to(dtype=utterance.dtype, device=utterance.device)
(
ffn0_out,
layer_norm_input_right_context,
layer_norm_input_utterance,
layer_norm_input_summary,
) = self._apply_pre_attention(utterance, right_context, summary)
if state is None:
state = self._init_state(layer_norm_input_utterance.size(1), device=layer_norm_input_utterance.device)
pre_mems, lc_key, lc_val, conv_cache = self._unpack_state(state)
rc_output, next_m, next_k, next_v = self.attention.infer(
utterance=layer_norm_input_utterance,
lengths=lengths,
right_context=layer_norm_input_right_context,
summary=layer_norm_input_summary,
mems=pre_mems,
left_context_key=lc_key,
left_context_val=lc_val,
)
output_utterance, output_right_context, conv_cache = self._apply_post_attention(
rc_output, ffn0_out, conv_cache, right_context.size(0), utterance.size(0)
)
output_state = self._pack_state(next_k, next_v, utterance.size(0), mems, conv_cache, state)
return output_utterance, output_right_context, output_state, next_m
[docs]class ConvEmformer(_EmformerImpl):
r"""Implements the convolution-augmented streaming transformer architecture introduced in
*Streaming Transformer Transducer based Speech Recognition Using Non-Causal Convolution*
:cite:`9747706`.
Args:
input_dim (int): input dimension.
num_heads (int): number of attention heads in each ConvEmformer layer.
ffn_dim (int): hidden layer dimension of each ConvEmformer layer's feedforward network.
num_layers (int): number of ConvEmformer layers to instantiate.
segment_length (int): length of each input segment.
kernel_size (int): size of kernel to use in convolution modules.
dropout (float, optional): dropout probability. (Default: 0.0)
ffn_activation (str, optional): activation function to use in feedforward networks.
Must be one of ("relu", "gelu", "silu"). (Default: "relu")
left_context_length (int, optional): length of left context. (Default: 0)
right_context_length (int, optional): length of right context. (Default: 0)
max_memory_size (int, optional): maximum number of memory elements to use. (Default: 0)
weight_init_scale_strategy (str or None, optional): per-layer weight initialization scaling
strategy. Must be one of ("depthwise", "constant", ``None``). (Default: "depthwise")
tanh_on_mem (bool, optional): if ``True``, applies tanh to memory elements. (Default: ``False``)
negative_inf (float, optional): value to use for negative infinity in attention weights. (Default: -1e8)
conv_activation (str, optional): activation function to use in convolution modules.
Must be one of ("relu", "gelu", "silu"). (Default: "silu")
Examples:
>>> conv_emformer = ConvEmformer(80, 4, 1024, 12, 16, 8, right_context_length=4)
>>> input = torch.rand(10, 200, 80)
>>> lengths = torch.randint(1, 200, (10,))
>>> output, lengths = conv_emformer(input, lengths)
>>> input = torch.rand(4, 20, 80)
>>> lengths = torch.ones(4) * 20
>>> output, lengths, states = conv_emformer.infer(input, lengths, None)
"""
def __init__(
self,
input_dim: int,
num_heads: int,
ffn_dim: int,
num_layers: int,
segment_length: int,
kernel_size: int,
dropout: float = 0.0,
ffn_activation: str = "relu",
left_context_length: int = 0,
right_context_length: int = 0,
max_memory_size: int = 0,
weight_init_scale_strategy: Optional[str] = "depthwise",
tanh_on_mem: bool = False,
negative_inf: float = -1e8,
conv_activation: str = "silu",
):
weight_init_gains = _get_weight_init_gains(weight_init_scale_strategy, num_layers)
emformer_layers = torch.nn.ModuleList(
[
_ConvEmformerLayer(
input_dim,
num_heads,
ffn_dim,
segment_length,
kernel_size,
dropout=dropout,
ffn_activation=ffn_activation,
left_context_length=left_context_length,
right_context_length=right_context_length,
max_memory_size=max_memory_size,
weight_init_gain=weight_init_gains[layer_idx],
tanh_on_mem=tanh_on_mem,
negative_inf=negative_inf,
conv_activation=conv_activation,
)
for layer_idx in range(num_layers)
]
)
super().__init__(
emformer_layers,
segment_length,
left_context_length=left_context_length,
right_context_length=right_context_length,
max_memory_size=max_memory_size,
)
