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import functools
from typing import Callable, Iterable, Union
import torch
from einops import rearrange, repeat
import comfy.ops
ops = comfy.ops.disable_weight_init
from .diffusionmodules.model import (
AttnBlock,
Decoder,
ResnetBlock,
)
from .diffusionmodules.openaimodel import ResBlock, timestep_embedding
from .attention import BasicTransformerBlock
def partialclass(cls, *args, **kwargs):
class NewCls(cls):
__init__ = functools.partialmethod(cls.__init__, *args, **kwargs)
return NewCls
class VideoResBlock(ResnetBlock):
def __init__(
self,
out_channels,
*args,
dropout=0.0,
video_kernel_size=3,
alpha=0.0,
merge_strategy="learned",
**kwargs,
):
super().__init__(out_channels=out_channels, dropout=dropout, *args, **kwargs)
if video_kernel_size is None:
video_kernel_size = [3, 1, 1]
self.time_stack = ResBlock(
channels=out_channels,
emb_channels=0,
dropout=dropout,
dims=3,
use_scale_shift_norm=False,
use_conv=False,
up=False,
down=False,
kernel_size=video_kernel_size,
use_checkpoint=False,
skip_t_emb=True,
)
self.merge_strategy = merge_strategy
if self.merge_strategy == "fixed":
self.register_buffer("mix_factor", torch.Tensor([alpha]))
elif self.merge_strategy == "learned":
self.register_parameter(
"mix_factor", torch.nn.Parameter(torch.Tensor([alpha]))
)
else:
raise ValueError(f"unknown merge strategy {self.merge_strategy}")
def get_alpha(self, bs):
if self.merge_strategy == "fixed":
return self.mix_factor
elif self.merge_strategy == "learned":
return torch.sigmoid(self.mix_factor)
else:
raise NotImplementedError()
def forward(self, x, temb, skip_video=False, timesteps=None):
b, c, h, w = x.shape
if timesteps is None:
timesteps = b
x = super().forward(x, temb)
if not skip_video:
x_mix = rearrange(x, "(b t) c h w -> b c t h w", t=timesteps)
x = rearrange(x, "(b t) c h w -> b c t h w", t=timesteps)
x = self.time_stack(x, temb)
alpha = self.get_alpha(bs=b // timesteps).to(x.device)
x = alpha * x + (1.0 - alpha) * x_mix
x = rearrange(x, "b c t h w -> (b t) c h w")
return x
class AE3DConv(ops.Conv2d):
def __init__(self, in_channels, out_channels, video_kernel_size=3, *args, **kwargs):
super().__init__(in_channels, out_channels, *args, **kwargs)
if isinstance(video_kernel_size, Iterable):
padding = [int(k // 2) for k in video_kernel_size]
else:
padding = int(video_kernel_size // 2)
self.time_mix_conv = ops.Conv3d(
in_channels=out_channels,
out_channels=out_channels,
kernel_size=video_kernel_size,
padding=padding,
)
def forward(self, input, timesteps=None, skip_video=False):
if timesteps is None:
timesteps = input.shape[0]
x = super().forward(input)
if skip_video:
return x
x = rearrange(x, "(b t) c h w -> b c t h w", t=timesteps)
x = self.time_mix_conv(x)
return rearrange(x, "b c t h w -> (b t) c h w")
class AttnVideoBlock(AttnBlock):
def __init__(
self, in_channels: int, alpha: float = 0, merge_strategy: str = "learned"
):
super().__init__(in_channels)
# no context, single headed, as in base class
self.time_mix_block = BasicTransformerBlock(
dim=in_channels,
n_heads=1,
d_head=in_channels,
checkpoint=False,
ff_in=True,
)
time_embed_dim = self.in_channels * 4
self.video_time_embed = torch.nn.Sequential(
ops.Linear(self.in_channels, time_embed_dim),
torch.nn.SiLU(),
ops.Linear(time_embed_dim, self.in_channels),
)
self.merge_strategy = merge_strategy
if self.merge_strategy == "fixed":
self.register_buffer("mix_factor", torch.Tensor([alpha]))
elif self.merge_strategy == "learned":
self.register_parameter(
"mix_factor", torch.nn.Parameter(torch.Tensor([alpha]))
)
else:
raise ValueError(f"unknown merge strategy {self.merge_strategy}")
def forward(self, x, timesteps=None, skip_time_block=False):
if skip_time_block:
return super().forward(x)
if timesteps is None:
timesteps = x.shape[0]
x_in = x
x = self.attention(x)
h, w = x.shape[2:]
x = rearrange(x, "b c h w -> b (h w) c")
x_mix = x
num_frames = torch.arange(timesteps, device=x.device)
num_frames = repeat(num_frames, "t -> b t", b=x.shape[0] // timesteps)
num_frames = rearrange(num_frames, "b t -> (b t)")
t_emb = timestep_embedding(num_frames, self.in_channels, repeat_only=False)
emb = self.video_time_embed(t_emb) # b, n_channels
emb = emb[:, None, :]
x_mix = x_mix + emb
alpha = self.get_alpha().to(x.device)
x_mix = self.time_mix_block(x_mix, timesteps=timesteps)
x = alpha * x + (1.0 - alpha) * x_mix # alpha merge
x = rearrange(x, "b (h w) c -> b c h w", h=h, w=w)
x = self.proj_out(x)
return x_in + x
def get_alpha(
self,
):
if self.merge_strategy == "fixed":
return self.mix_factor
elif self.merge_strategy == "learned":
return torch.sigmoid(self.mix_factor)
else:
raise NotImplementedError(f"unknown merge strategy {self.merge_strategy}")
def make_time_attn(
in_channels,
attn_type="vanilla",
attn_kwargs=None,
alpha: float = 0,
merge_strategy: str = "learned",
):
return partialclass(
AttnVideoBlock, in_channels, alpha=alpha, merge_strategy=merge_strategy
)
class Conv2DWrapper(torch.nn.Conv2d):
def forward(self, input: torch.Tensor, **kwargs) -> torch.Tensor:
return super().forward(input)
class VideoDecoder(Decoder):
available_time_modes = ["all", "conv-only", "attn-only"]
def __init__(
self,
*args,
video_kernel_size: Union[int, list] = 3,
alpha: float = 0.0,
merge_strategy: str = "learned",
time_mode: str = "conv-only",
**kwargs,
):
self.video_kernel_size = video_kernel_size
self.alpha = alpha
self.merge_strategy = merge_strategy
self.time_mode = time_mode
assert (
self.time_mode in self.available_time_modes
), f"time_mode parameter has to be in {self.available_time_modes}"
if self.time_mode != "attn-only":
kwargs["conv_out_op"] = partialclass(AE3DConv, video_kernel_size=self.video_kernel_size)
if self.time_mode not in ["conv-only", "only-last-conv"]:
kwargs["attn_op"] = partialclass(make_time_attn, alpha=self.alpha, merge_strategy=self.merge_strategy)
if self.time_mode not in ["attn-only", "only-last-conv"]:
kwargs["resnet_op"] = partialclass(VideoResBlock, video_kernel_size=self.video_kernel_size, alpha=self.alpha, merge_strategy=self.merge_strategy)
super().__init__(*args, **kwargs)
def get_last_layer(self, skip_time_mix=False, **kwargs):
if self.time_mode == "attn-only":
raise NotImplementedError("TODO")
else:
return (
self.conv_out.time_mix_conv.weight
if not skip_time_mix
else self.conv_out.weight
)
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