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# Copyright 2024 The HuggingFace Team. 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.
from typing import List, Optional, Tuple, Union
import torch
from torch import nn
from diffusers.models.activations import get_activation
class TimestepEmbedding(nn.Module):
def __init__(
self,
in_channels: int,
time_embed_dim: int,
act_fn: str = "silu",
out_dim: int = None,
post_act_fn: Optional[str] = None,
cond_proj_dim=None,
sample_proj_bias=True,
):
super().__init__()
self.linear_1 = nn.Linear(in_channels, time_embed_dim, sample_proj_bias)
if cond_proj_dim is not None:
self.cond_proj = nn.Linear(cond_proj_dim, in_channels, bias=False)
else:
self.cond_proj = None
self.act = get_activation(act_fn)
if out_dim is not None:
time_embed_dim_out = out_dim
else:
time_embed_dim_out = time_embed_dim
self.linear_2 = nn.Linear(time_embed_dim, time_embed_dim_out, sample_proj_bias)
if post_act_fn is None:
self.post_act = None
else:
self.post_act = get_activation(post_act_fn)
self.initialize_weights()
def initialize_weights(self):
nn.init.normal_(self.linear_1.weight, std=0.02)
nn.init.zeros_(self.linear_1.bias)
nn.init.normal_(self.linear_2.weight, std=0.02)
nn.init.zeros_(self.linear_2.bias)
def forward(self, sample, condition=None):
if condition is not None:
sample = sample + self.cond_proj(condition)
sample = self.linear_1(sample)
if self.act is not None:
sample = self.act(sample)
sample = self.linear_2(sample)
if self.post_act is not None:
sample = self.post_act(sample)
return sample
def apply_rotary_emb(
x: torch.Tensor,
freqs_cis: Union[torch.Tensor, Tuple[torch.Tensor]],
use_real: bool = True,
use_real_unbind_dim: int = -1,
) -> Tuple[torch.Tensor, torch.Tensor]:
"""
Apply rotary embeddings to input tensors using the given frequency tensor. This function applies rotary embeddings
to the given query or key 'x' tensors using the provided frequency tensor 'freqs_cis'. The input tensors are
reshaped as complex numbers, and the frequency tensor is reshaped for broadcasting compatibility. The resulting
tensors contain rotary embeddings and are returned as real tensors.
Args:
x (`torch.Tensor`):
Query or key tensor to apply rotary embeddings. [B, H, S, D] xk (torch.Tensor): Key tensor to apply
freqs_cis (`Tuple[torch.Tensor]`): Precomputed frequency tensor for complex exponentials. ([S, D], [S, D],)
Returns:
Tuple[torch.Tensor, torch.Tensor]: Tuple of modified query tensor and key tensor with rotary embeddings.
"""
if use_real:
cos, sin = freqs_cis # [S, D]
cos = cos[None, None]
sin = sin[None, None]
cos, sin = cos.to(x.device), sin.to(x.device)
if use_real_unbind_dim == -1:
# Used for flux, cogvideox, hunyuan-dit
x_real, x_imag = x.reshape(*x.shape[:-1], -1, 2).unbind(-1) # [B, S, H, D//2]
x_rotated = torch.stack([-x_imag, x_real], dim=-1).flatten(3)
elif use_real_unbind_dim == -2:
# Used for Stable Audio, OmniGen and CogView4
x_real, x_imag = x.reshape(*x.shape[:-1], 2, -1).unbind(-2) # [B, S, H, D//2]
x_rotated = torch.cat([-x_imag, x_real], dim=-1)
else:
raise ValueError(f"`use_real_unbind_dim={use_real_unbind_dim}` but should be -1 or -2.")
out = (x.float() * cos + x_rotated.float() * sin).to(x.dtype)
return out
else:
# used for lumina
# x_rotated = torch.view_as_complex(x.float().reshape(*x.shape[:-1], -1, 2))
x_rotated = torch.view_as_complex(x.float().reshape(*x.shape[:-1], x.shape[-1] // 2, 2))
freqs_cis = freqs_cis.unsqueeze(2)
x_out = torch.view_as_real(x_rotated * freqs_cis).flatten(3)
return x_out.type_as(x) |