# Copyright 2019 Shigeki Karita # Apache 2.0 (http://www.apache.org/licenses/LICENSE-2.0) """Transformer encoder definition.""" from typing import List from typing import Optional from typing import Tuple import torch from torch import nn import logging from funasr.models.transformer.attention import MultiHeadedAttention from funasr.models.transformer.embedding import PositionalEncoding from funasr.models.transformer.layer_norm import LayerNorm from funasr.models.transformer.utils.multi_layer_conv import Conv1dLinear from funasr.models.transformer.utils.multi_layer_conv import MultiLayeredConv1d from funasr.models.transformer.utils.nets_utils import make_pad_mask from funasr.models.transformer.positionwise_feed_forward import PositionwiseFeedForward from funasr.models.transformer.utils.repeat import repeat from funasr.models.ctc.ctc import CTC from funasr.models.transformer.utils.subsampling import Conv2dSubsampling from funasr.models.transformer.utils.subsampling import Conv2dSubsampling2 from funasr.models.transformer.utils.subsampling import Conv2dSubsampling6 from funasr.models.transformer.utils.subsampling import Conv2dSubsampling8 from funasr.models.transformer.utils.subsampling import TooShortUttError from funasr.models.transformer.utils.subsampling import check_short_utt from funasr.register import tables class EncoderLayer(nn.Module): """Encoder layer module. Args: size (int): Input dimension. self_attn (torch.nn.Module): Self-attention module instance. `MultiHeadedAttention` or `RelPositionMultiHeadedAttention` instance can be used as the argument. feed_forward (torch.nn.Module): Feed-forward module instance. `PositionwiseFeedForward`, `MultiLayeredConv1d`, or `Conv1dLinear` 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, 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.norm1 = LayerNorm(size) self.norm2 = LayerNorm(size) 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, mask, cache=None): """Compute encoded features. Args: x_input (torch.Tensor): Input tensor (#batch, time, size). mask (torch.Tensor): Mask tensor for the input (#batch, time). cache (torch.Tensor): Cache tensor of the input (#batch, time - 1, size). Returns: torch.Tensor: Output tensor (#batch, time, size). torch.Tensor: Mask tensor (#batch, time). """ 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 = torch.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 = torch.cat([cache, x], dim=1) return x, mask residual = x if self.normalize_before: x = self.norm1(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 self.concat_after: x_concat = torch.cat((x, self.self_attn(x_q, x, x, mask)), dim=-1) x = residual + stoch_layer_coeff * self.concat_linear(x_concat) else: x = residual + stoch_layer_coeff * self.dropout(self.self_attn(x_q, x, x, mask)) if not self.normalize_before: x = self.norm1(x) residual = x if self.normalize_before: x = self.norm2(x) x = residual + stoch_layer_coeff * self.dropout(self.feed_forward(x)) if not self.normalize_before: x = self.norm2(x) if cache is not None: x = torch.cat([cache, x], dim=1) return x, mask @tables.register("encoder_classes", "TransformerEncoder") class TransformerEncoder(nn.Module): """Transformer encoder module. Args: input_size: input dim output_size: dimension of attention attention_heads: the number of heads of multi head attention linear_units: the number of units of position-wise feed forward num_blocks: the number of decoder blocks dropout_rate: dropout rate attention_dropout_rate: dropout rate in attention positional_dropout_rate: dropout rate after adding positional encoding input_layer: input layer type pos_enc_class: PositionalEncoding or ScaledPositionalEncoding normalize_before: whether to use layer_norm before the first block concat_after: 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) positionwise_layer_type: linear of conv1d positionwise_conv_kernel_size: kernel size of positionwise conv1d layer padding_idx: padding_idx for input_layer=embed """ def __init__( self, input_size: int, output_size: int = 256, attention_heads: int = 4, linear_units: int = 2048, num_blocks: int = 6, dropout_rate: float = 0.1, positional_dropout_rate: float = 0.1, attention_dropout_rate: float = 0.0, input_layer: Optional[str] = "conv2d", pos_enc_class=PositionalEncoding, normalize_before: bool = True, concat_after: bool = False, positionwise_layer_type: str = "linear", positionwise_conv_kernel_size: int = 1, padding_idx: int = -1, interctc_layer_idx: List[int] = [], interctc_use_conditioning: bool = False, ): super().__init__() self._output_size = output_size if input_layer == "linear": self.embed = torch.nn.Sequential( torch.nn.Linear(input_size, output_size), torch.nn.LayerNorm(output_size), torch.nn.Dropout(dropout_rate), torch.nn.ReLU(), pos_enc_class(output_size, positional_dropout_rate), ) elif input_layer == "conv2d": self.embed = Conv2dSubsampling(input_size, output_size, dropout_rate) elif input_layer == "conv2d2": self.embed = Conv2dSubsampling2(input_size, output_size, dropout_rate) elif input_layer == "conv2d6": self.embed = Conv2dSubsampling6(input_size, output_size, dropout_rate) elif input_layer == "conv2d8": self.embed = Conv2dSubsampling8(input_size, output_size, dropout_rate) elif input_layer == "embed": self.embed = torch.nn.Sequential( torch.nn.Embedding(input_size, output_size, padding_idx=padding_idx), pos_enc_class(output_size, positional_dropout_rate), ) elif input_layer is None: if input_size == output_size: self.embed = None else: self.embed = torch.nn.Linear(input_size, output_size) else: raise ValueError("unknown input_layer: " + input_layer) self.normalize_before = normalize_before if positionwise_layer_type == "linear": positionwise_layer = PositionwiseFeedForward positionwise_layer_args = ( output_size, linear_units, dropout_rate, ) elif positionwise_layer_type == "conv1d": positionwise_layer = MultiLayeredConv1d positionwise_layer_args = ( output_size, linear_units, positionwise_conv_kernel_size, dropout_rate, ) elif positionwise_layer_type == "conv1d-linear": positionwise_layer = Conv1dLinear positionwise_layer_args = ( output_size, linear_units, positionwise_conv_kernel_size, dropout_rate, ) else: raise NotImplementedError("Support only linear or conv1d.") self.encoders = repeat( num_blocks, lambda lnum: EncoderLayer( output_size, MultiHeadedAttention(attention_heads, output_size, attention_dropout_rate), positionwise_layer(*positionwise_layer_args), dropout_rate, normalize_before, concat_after, ), ) if self.normalize_before: self.after_norm = LayerNorm(output_size) self.interctc_layer_idx = interctc_layer_idx if len(interctc_layer_idx) > 0: assert 0 < min(interctc_layer_idx) and max(interctc_layer_idx) < num_blocks self.interctc_use_conditioning = interctc_use_conditioning self.conditioning_layer = None def output_size(self) -> int: return self._output_size def forward( self, xs_pad: torch.Tensor, ilens: torch.Tensor, prev_states: torch.Tensor = None, ctc: CTC = None, ) -> Tuple[torch.Tensor, torch.Tensor, Optional[torch.Tensor]]: """Embed positions in tensor. Args: xs_pad: input tensor (B, L, D) ilens: input length (B) prev_states: Not to be used now. Returns: position embedded tensor and mask """ masks = (~make_pad_mask(ilens)[:, None, :]).to(xs_pad.device) if self.embed is None: xs_pad = xs_pad elif ( isinstance(self.embed, Conv2dSubsampling) or isinstance(self.embed, Conv2dSubsampling2) or isinstance(self.embed, Conv2dSubsampling6) or isinstance(self.embed, Conv2dSubsampling8) ): short_status, limit_size = check_short_utt(self.embed, xs_pad.size(1)) if short_status: raise TooShortUttError( f"has {xs_pad.size(1)} frames and is too short for subsampling " + f"(it needs more than {limit_size} frames), return empty results", xs_pad.size(1), limit_size, ) xs_pad, masks = self.embed(xs_pad, masks) else: xs_pad = self.embed(xs_pad) intermediate_outs = [] if len(self.interctc_layer_idx) == 0: xs_pad, masks = self.encoders(xs_pad, masks) else: for layer_idx, encoder_layer in enumerate(self.encoders): xs_pad, masks = encoder_layer(xs_pad, masks) if layer_idx + 1 in self.interctc_layer_idx: encoder_out = xs_pad # intermediate outputs are also normalized if self.normalize_before: encoder_out = self.after_norm(encoder_out) intermediate_outs.append((layer_idx + 1, encoder_out)) if self.interctc_use_conditioning: ctc_out = ctc.softmax(encoder_out) xs_pad = xs_pad + self.conditioning_layer(ctc_out) if self.normalize_before: xs_pad = self.after_norm(xs_pad) olens = masks.squeeze(1).sum(1) if len(intermediate_outs) > 0: return (xs_pad, intermediate_outs), olens, None return xs_pad, olens, None