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# modified from https://github.com/lifeiteng/vall-e/blob/main/valle/modules/embedding.py
import math
import torch
from torch import nn
class TokenEmbedding(nn.Module):
def __init__(
self,
embedding_dim: int,
vocab_size: int,
dropout: float = 0.0,
):
super().__init__()
self.vocab_size = vocab_size
self.embedding_dim = embedding_dim
self.dropout = torch.nn.Dropout(p=dropout)
self.word_embeddings = nn.Embedding(self.vocab_size, self.embedding_dim)
@property
def weight(self) -> torch.Tensor:
return self.word_embeddings.weight
def embedding(self, index: int) -> torch.Tensor:
return self.word_embeddings.weight[index : index + 1]
def forward(self, x: torch.Tensor):
x = self.word_embeddings(x)
x = self.dropout(x)
return x
class SinePositionalEmbedding(nn.Module):
def __init__(
self,
embedding_dim: int,
dropout: float = 0.0,
scale: bool = False,
alpha: bool = False,
):
super().__init__()
self.embedding_dim = embedding_dim
self.x_scale = math.sqrt(embedding_dim) if scale else 1.0
self.alpha = nn.Parameter(torch.ones(1), requires_grad=alpha)
self.dropout = torch.nn.Dropout(p=dropout)
self.reverse = False
self.pe = None
self.extend_pe(torch.tensor(0.0).expand(1, 4000))
def extend_pe(self, x):
"""Reset the positional encodings."""
if self.pe is not None:
if self.pe.size(1) >= x.size(1):
if self.pe.dtype != x.dtype or self.pe.device != x.device:
self.pe = self.pe.to(dtype=x.dtype, device=x.device)
return
pe = torch.zeros(x.size(1), self.embedding_dim)
if self.reverse:
position = torch.arange(
x.size(1) - 1, -1, -1.0, dtype=torch.float32
).unsqueeze(1)
else:
position = torch.arange(0, x.size(1), dtype=torch.float32).unsqueeze(1)
div_term = torch.exp(
torch.arange(0, self.embedding_dim, 2, dtype=torch.float32)
* -(math.log(10000.0) / self.embedding_dim)
)
pe[:, 0::2] = torch.sin(position * div_term)
pe[:, 1::2] = torch.cos(position * div_term)
pe = pe.unsqueeze(0)
self.pe = pe.to(device=x.device, dtype=x.dtype).detach()
def forward(self, x: torch.Tensor) -> torch.Tensor:
self.extend_pe(x)
output = x.unsqueeze(-1) if x.ndim == 2 else x
output = output * self.x_scale + self.alpha * self.pe[:, : x.size(1)]
return self.dropout(output)
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