Open-Sora/open_sora/modeling/dit/dit.py
Frank Lee 9648d53d4d
added latte sampling (#22)
* added latte sampling

* polish
2024-03-04 10:43:22 +08:00

593 lines
21 KiB
Python

# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.
# --------------------------------------------------------
# References:
# GLIDE: https://github.com/openai/glide-text2im
# MAE: https://github.com/facebookresearch/mae/blob/main/models_mae.py
# --------------------------------------------------------
import math
from typing import Callable, Optional
import numpy as np
import torch
import torch.distributed as dist
import torch.nn as nn
import torch.nn.functional as F
from timm.models.vision_transformer import Mlp
from open_sora.utils.comm import gather_seq, split_seq
from .attn import CrossAttention, FastSeqParallelCrossAttention, SeqParallelCrossAttention
SUPPORTED_SEQ_PARALLEL_MODES = ["ulysses", "fastseq"]
def modulate(x, shift, scale):
return x * (1 + scale.unsqueeze(1)) + shift.unsqueeze(1)
#################################################################################
# Embedding Layers for Timesteps and Class Labels #
#################################################################################
class TimestepEmbedder(nn.Module):
"""
Embeds scalar timesteps into vector representations.
"""
def __init__(self, hidden_size, frequency_embedding_size=256):
super().__init__()
self.mlp = nn.Sequential(
nn.Linear(frequency_embedding_size, hidden_size, bias=True),
nn.SiLU(),
nn.Linear(hidden_size, hidden_size, bias=True),
)
self.frequency_embedding_size = frequency_embedding_size
@staticmethod
def timestep_embedding(t, dim, max_period=10000):
"""
Create sinusoidal timestep embeddings.
:param t: a 1-D Tensor of N indices, one per batch element.
These may be fractional.
:param dim: the dimension of the output.
:param max_period: controls the minimum frequency of the embeddings.
:return: an (N, D) Tensor of positional embeddings.
"""
# https://github.com/openai/glide-text2im/blob/main/glide_text2im/nn.py
half = dim // 2
freqs = torch.exp(-math.log(max_period) * torch.arange(start=0, end=half, dtype=torch.float32) / half).to(
device=t.device
)
args = t[:, None].float() * freqs[None]
embedding = torch.cat([torch.cos(args), torch.sin(args)], dim=-1)
if dim % 2:
embedding = torch.cat([embedding, torch.zeros_like(embedding[:, :1])], dim=-1)
return embedding
def forward(self, t):
t_freq = self.timestep_embedding(t, self.frequency_embedding_size).to(self.mlp[0].weight.dtype)
t_emb = self.mlp(t_freq)
return t_emb
class LabelEmbedder(nn.Module):
"""
Embeds class labels into vector representations. Also handles label dropout for classifier-free guidance.
"""
def __init__(self, num_classes, hidden_size, dropout_prob):
super().__init__()
use_cfg_embedding = dropout_prob > 0
self.embedding_table = nn.Embedding(num_classes + use_cfg_embedding, hidden_size)
self.num_classes = num_classes
self.dropout_prob = dropout_prob
def token_drop(self, labels, force_drop_ids=None):
"""
Drops labels to enable classifier-free guidance.
"""
if force_drop_ids is None:
drop_ids = torch.rand(labels.shape[0], device=labels.device) < self.dropout_prob
else:
drop_ids = force_drop_ids == 1
labels = torch.where(drop_ids, self.num_classes, labels)
return labels
def forward(self, labels, train, force_drop_ids=None):
use_dropout = self.dropout_prob > 0
if (train and use_dropout) or (force_drop_ids is not None):
labels = self.token_drop(labels, force_drop_ids)
embeddings = self.embedding_table(labels)
return embeddings
class PatchEmbedder(nn.Module):
"""Patch Embedding Layer for flat 4D video tensors."""
def __init__(
self,
patch_size: int = 16,
in_chans: int = 3,
embed_dim: int = 768,
norm_layer: Optional[Callable] = None,
bias: bool = True,
) -> None:
super().__init__()
self.patch_size = patch_size
self.proj = nn.Conv2d(in_chans, embed_dim, kernel_size=patch_size, stride=patch_size, bias=bias)
self.norm = norm_layer(embed_dim) if norm_layer else nn.Identity()
def forward(self, x: torch.Tensor) -> torch.Tensor:
# [B, S, C, P, P] -> [B, S, C*P*P]
x = x.view(*x.shape[:2], -1)
out = F.linear(x, self.proj.weight.view(self.proj.weight.shape[0], -1), self.proj.bias)
out = self.norm(out)
# [B, S, H]
return out
class TextEmbedder(nn.Module):
def __init__(
self,
in_features: int,
embed_dim: int = 768,
bias: bool = True,
dropout_prob: float = 0.0,
use_proj: bool = True,
) -> None:
super().__init__()
self.dropout_prob = dropout_prob
self.use_proj = use_proj
if self.use_proj:
self.proj = nn.Linear(in_features, embed_dim, bias=bias)
def drop_sample(self, x: torch.Tensor) -> torch.Tensor:
drop_ids = torch.rand(x.shape[0], 1, 1, device=x.device) < self.dropout_prob
x = torch.where(drop_ids, torch.zeros_like(x), x)
return x
def forward(self, x: torch.Tensor) -> torch.Tensor:
use_dropout = self.dropout_prob > 0
if self.training and use_dropout:
x = self.drop_sample(x)
if self.use_proj:
# [B, S, C] -> [B, S, H]
x = self.proj(x)
return x
class PositionEmbedding(nn.Module):
def __init__(self, dim: int, max_position_embeddings=262114) -> None:
super().__init__()
self.dim = dim
self.max_position_embeddings = max_position_embeddings
self._set_pos_embed_cache(max_position_embeddings)
def _set_pos_embed_cache(self, seq_len: int, device="cpu", dtype=torch.float):
self.max_seq_len_cached = seq_len
pos_embed = get_2d_sincos_pos_embed(self.dim, math.ceil(seq_len**0.5))
pos_embed = torch.from_numpy(pos_embed).to(device=device, dtype=dtype)
# [S, H]
self.register_buffer("pos_embed_cache", pos_embed, persistent=False)
def forward(self, x: torch.Tensor) -> torch.Tensor:
# [B, S, H]
seq_len = x.shape[1]
if seq_len > self.max_seq_len_cached:
self._set_pos_embed_cache(seq_len, x.device, x.dtype)
pos_embed = self.pos_embed_cache[None, :seq_len]
return pos_embed
#################################################################################
# Core DiT Model #
#################################################################################
class DiTBlock(nn.Module):
"""
A DiT block with adaptive layer norm zero (adaLN-Zero) conditioning.
"""
def __init__(
self,
hidden_size,
num_heads,
cross_attention_dim=None,
mlp_ratio=4.0,
seq_parallel_group=None,
seq_parallel_mode="ulysses",
seq_parallel_overlap=False,
):
super().__init__()
self.norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
attn_kwargs = {}
if seq_parallel_group is not None:
attn_kwargs["seq_parallel_group"] = seq_parallel_group
if seq_parallel_mode == "ulysses":
attn_cls = SeqParallelCrossAttention
elif seq_parallel_mode == "fastseq":
attn_cls = FastSeqParallelCrossAttention
attn_kwargs["overlap"] = seq_parallel_overlap
else:
raise ValueError(f"seq_parallel_mode must be one of {SUPPORTED_SEQ_PARALLEL_MODES}")
else:
attn_cls = CrossAttention
self.attn = attn_cls(
query_dim=hidden_size,
cross_attention_dim=cross_attention_dim,
num_heads=num_heads,
head_dim=hidden_size // num_heads,
bias=True,
sdpa=True,
**attn_kwargs,
)
self.norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
mlp_hidden_dim = int(hidden_size * mlp_ratio)
approx_gelu = lambda: nn.GELU(approximate="tanh")
self.mlp = Mlp(
in_features=hidden_size,
hidden_features=mlp_hidden_dim,
act_layer=approx_gelu,
drop=0,
)
self.mlp = Mlp(
in_features=hidden_size,
hidden_features=mlp_hidden_dim,
act_layer=approx_gelu,
drop=0,
)
self.adaLN_modulation = nn.Sequential(nn.SiLU(), nn.Linear(hidden_size, 6 * hidden_size, bias=True))
def forward(self, x, attention_mask, t, context=None):
shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = self.adaLN_modulation(t).chunk(6, dim=1)
x = x + gate_msa.unsqueeze(1) * self.attn(
modulate(self.norm1(x), shift_msa, scale_msa), context, attention_mask
)
x = x + gate_mlp.unsqueeze(1) * self.mlp(modulate(self.norm2(x), shift_mlp, scale_mlp))
return x
class FinalLayer(nn.Module):
"""
The final layer of DiT.
"""
def __init__(self, hidden_size, patch_size, out_channels):
super().__init__()
self.norm_final = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
self.linear = nn.Linear(hidden_size, patch_size * patch_size * out_channels, bias=True)
self.patch_size = patch_size
self.adaLN_modulation = nn.Sequential(nn.SiLU(), nn.Linear(hidden_size, 2 * hidden_size, bias=True))
def unpatchify(self, x):
b, s, h = x.shape
return x.view(b, s, -1, self.patch_size, self.patch_size)
def forward(self, x, t):
shift, scale = self.adaLN_modulation(t).chunk(2, dim=1)
x = modulate(self.norm_final(x), shift, scale)
x = self.linear(x)
x = self.unpatchify(x)
return x
class DiT(nn.Module):
"""
Diffusion model with a Transformer backbone.
"""
def __init__(
self,
patch_size=2,
in_channels=3,
text_embed_dim=512,
hidden_size=1152,
depth=28,
num_heads=16,
mlp_ratio=4.0,
max_num_embeddings=256 * 1024,
text_dropout_prob=0.1,
learn_sigma=True,
use_cross_attn=True,
seq_parallel_group=None,
seq_parallel_mode="ulysses",
seq_parallel_overlap=False,
):
super().__init__()
self.grad_checkpointing = False
self.learn_sigma = learn_sigma
self.in_channels = in_channels
self.out_channels = in_channels * 2 if learn_sigma else in_channels
self.patch_size = patch_size
self.num_heads = num_heads
self.seq_parallel_group = seq_parallel_group
self.seq_parallel_size = dist.get_world_size(self.seq_parallel_group) if seq_parallel_group is not None else 1
self.seq_parallel_rank = dist.get_rank(self.seq_parallel_group) if seq_parallel_group is not None else 0
self.video_embedder = PatchEmbedder(patch_size, in_channels, hidden_size, bias=True)
self.t_embedder = TimestepEmbedder(hidden_size)
self.pos_embed = PositionEmbedding(hidden_size, max_num_embeddings)
self.text_embedder = TextEmbedder(
text_embed_dim,
hidden_size,
bias=True,
dropout_prob=text_dropout_prob,
use_proj=not use_cross_attn,
)
if not use_cross_attn:
cross_attn_dim = None
else:
cross_attn_dim = text_embed_dim
self.use_cross_attn = use_cross_attn
self.blocks = nn.ModuleList(
[
DiTBlock(
hidden_size,
num_heads,
cross_attn_dim,
mlp_ratio=mlp_ratio,
seq_parallel_group=seq_parallel_group,
seq_parallel_mode=seq_parallel_mode,
seq_parallel_overlap=seq_parallel_overlap,
)
for _ in range(depth)
]
)
self.final_layer = FinalLayer(hidden_size, patch_size, self.out_channels)
self.initialize_weights()
def initialize_weights(self):
# Initialize transformer layers:
def _basic_init(module):
if isinstance(module, nn.Linear):
torch.nn.init.xavier_uniform_(module.weight)
if module.bias is not None:
nn.init.constant_(module.bias, 0)
self.apply(_basic_init)
# Initialize text embedding layer
if self.text_embedder.use_proj:
nn.init.normal_(self.text_embedder.proj.weight, std=0.02)
# Initialize timestep embedding MLP:
nn.init.normal_(self.t_embedder.mlp[0].weight, std=0.02)
nn.init.normal_(self.t_embedder.mlp[2].weight, std=0.02)
# Zero-out adaLN modulation layers
for block in self.blocks:
nn.init.constant_(block.adaLN_modulation[-1].weight, 0)
nn.init.constant_(block.adaLN_modulation[-1].bias, 0)
# Zero-out output
nn.init.constant_(self.final_layer.adaLN_modulation[-1].weight, 0)
nn.init.constant_(self.final_layer.adaLN_modulation[-1].bias, 0)
nn.init.constant_(self.final_layer.linear.weight, 0)
nn.init.constant_(self.final_layer.linear.bias, 0)
def _prepare_mask(self, attention_mask: Optional[torch.Tensor], dtype: torch.dtype):
if attention_mask is not None:
assert attention_mask.ndim == 4
attention_mask = attention_mask.to(dtype)
inverted_mask = 1.0 - attention_mask
return inverted_mask.masked_fill(inverted_mask.to(torch.bool), torch.finfo(dtype).min)
return attention_mask
def enable_gradient_checkpointing(self):
self.grad_checkpointing = True
def disable_gradient_checkpointing(self):
self.grad_checkpointing = False
def forward(
self,
video_latent_states,
t,
text_latent_states=None,
attention_mask=None,
):
"""
video_latent_states: [B, S, C, P, P]
"""
video_latent_states = self.video_embedder(video_latent_states)
text_len = text_latent_states.shape[1]
text_latent_states = self.text_embedder(text_latent_states)
if not self.use_cross_attn:
video_latent_states = torch.cat([text_latent_states, video_latent_states], dim=1)
text_latent_states = None
pos_embed = self.pos_embed(video_latent_states)
video_latent_states = video_latent_states + pos_embed
t = self.t_embedder(t) # (N, D)
attention_mask = self._prepare_mask(attention_mask, video_latent_states.dtype)
if self.seq_parallel_group is not None and self.seq_parallel_size > 1:
assert video_latent_states.shape[1] % self.seq_parallel_size == 0
video_latent_states = split_seq(video_latent_states, self.seq_parallel_size, self.seq_parallel_rank)
if text_latent_states is not None:
assert text_latent_states.shape[1] % self.seq_parallel_size == 0
text_latent_states = split_seq(text_latent_states, self.seq_parallel_size, self.seq_parallel_rank)
for block in self.blocks:
if self.grad_checkpointing and self.training:
video_latent_states = torch.utils.checkpoint.checkpoint(
block,
video_latent_states,
attention_mask,
t,
text_latent_states,
)
else:
video_latent_states = block(video_latent_states, attention_mask, t, text_latent_states)
if self.seq_parallel_group is not None and self.seq_parallel_size > 1:
video_latent_states = gather_seq(
video_latent_states,
self.seq_parallel_size,
self.seq_parallel_rank,
self.seq_parallel_group,
)
if not self.use_cross_attn:
video_latent_states = video_latent_states[:, text_len:]
video_latent_states = self.final_layer(video_latent_states, t)
return video_latent_states
def forward_with_cfg(self, x, t, text_latent_states, cfg_scale, attention_mask=None):
"""
Forward pass of DiT, but also batches the unconditional forward pass for classifier-free guidance.
"""
# https://github.com/openai/glide-text2im/blob/main/notebooks/text2im.ipynb
half = x[: len(x) // 2]
combined = torch.cat([half, half], dim=0)
model_out = self.forward(combined, t, text_latent_states, attention_mask=attention_mask)
# For exact reproducibility reasons, we apply classifier-free guidance on only
# three channels by default. The standard approach to cfg applies it to all channels.
# This can be done by uncommenting the following line and commenting-out the line following that.
# eps, rest = model_out[:, :self.in_channels], model_out[:, self.in_channels:]
if self.learn_sigma:
c = model_out.shape[2]
assert c == 2 * self.in_channels
eps, rest = model_out.chunk(2, dim=2)
else:
eps = model_out
cond_eps, uncond_eps = torch.split(eps, len(eps) // 2, dim=0)
half_eps = uncond_eps + cfg_scale * (cond_eps - uncond_eps)
eps = torch.cat([half_eps, half_eps], dim=0)
if self.learn_sigma:
return torch.cat([eps, rest], dim=2)
return eps
#################################################################################
# Sine/Cosine Positional Embedding Functions #
#################################################################################
# https://github.com/facebookresearch/mae/blob/main/util/pos_embed.py
def get_2d_sincos_pos_embed(embed_dim, grid_size, cls_token=False, extra_tokens=0):
"""
grid_size: int of the grid height and width
return:
pos_embed: [grid_size*grid_size, embed_dim] or [1+grid_size*grid_size, embed_dim] (w/ or w/o cls_token)
"""
grid_h = np.arange(grid_size, dtype=np.float32)
grid_w = np.arange(grid_size, dtype=np.float32)
grid = np.meshgrid(grid_w, grid_h) # here w goes first
grid = np.stack(grid, axis=0)
grid = grid.reshape([2, 1, grid_size, grid_size])
pos_embed = get_2d_sincos_pos_embed_from_grid(embed_dim, grid)
if cls_token and extra_tokens > 0:
pos_embed = np.concatenate([np.zeros([extra_tokens, embed_dim]), pos_embed], axis=0)
return pos_embed
def get_2d_sincos_pos_embed_from_grid(embed_dim, grid):
assert embed_dim % 2 == 0
# use half of dimensions to encode grid_h
emb_h = get_1d_sincos_pos_embed_from_grid(embed_dim // 2, grid[0]) # (H*W, D/2)
emb_w = get_1d_sincos_pos_embed_from_grid(embed_dim // 2, grid[1]) # (H*W, D/2)
emb = np.concatenate([emb_h, emb_w], axis=1) # (H*W, D)
return emb
def get_1d_sincos_pos_embed_from_grid(embed_dim, pos):
"""
embed_dim: output dimension for each position
pos: a list of positions to be encoded: size (M,)
out: (M, D)
"""
assert embed_dim % 2 == 0
omega = np.arange(embed_dim // 2, dtype=np.float64)
omega /= embed_dim / 2.0
omega = 1.0 / 10000**omega # (D/2,)
pos = pos.reshape(-1) # (M,)
out = np.einsum("m,d->md", pos, omega) # (M, D/2), outer product
emb_sin = np.sin(out) # (M, D/2)
emb_cos = np.cos(out) # (M, D/2)
emb = np.concatenate([emb_sin, emb_cos], axis=1) # (M, D)
return emb
#################################################################################
# DiT Configs #
#################################################################################
def DiT_XL_2(**kwargs):
return DiT(depth=28, hidden_size=1152, patch_size=2, num_heads=16, **kwargs)
def DiT_XL_4(**kwargs):
return DiT(depth=28, hidden_size=1152, patch_size=4, num_heads=16, **kwargs)
def DiT_XL_8(**kwargs):
return DiT(depth=28, hidden_size=1152, patch_size=8, num_heads=16, **kwargs)
def DiT_L_2(**kwargs):
return DiT(depth=24, hidden_size=1024, patch_size=2, num_heads=16, **kwargs)
def DiT_L_4(**kwargs):
return DiT(depth=24, hidden_size=1024, patch_size=4, num_heads=16, **kwargs)
def DiT_L_8(**kwargs):
return DiT(depth=24, hidden_size=1024, patch_size=8, num_heads=16, **kwargs)
def DiT_B_2(**kwargs):
return DiT(depth=12, hidden_size=768, patch_size=2, num_heads=12, **kwargs)
def DiT_B_4(**kwargs):
return DiT(depth=12, hidden_size=768, patch_size=4, num_heads=12, **kwargs)
def DiT_B_8(**kwargs):
return DiT(depth=12, hidden_size=768, patch_size=8, num_heads=12, **kwargs)
def DiT_S_2(**kwargs):
return DiT(depth=12, hidden_size=384, patch_size=2, num_heads=6, **kwargs)
def DiT_S_4(**kwargs):
return DiT(depth=12, hidden_size=384, patch_size=4, num_heads=6, **kwargs)
def DiT_S_8(**kwargs):
return DiT(depth=12, hidden_size=384, patch_size=8, num_heads=6, **kwargs)
DiT_models = {
"DiT-XL/2": DiT_XL_2,
"DiT-XL/4": DiT_XL_4,
"DiT-XL/8": DiT_XL_8,
"DiT-L/2": DiT_L_2,
"DiT-L/4": DiT_L_4,
"DiT-L/8": DiT_L_8,
"DiT-B/2": DiT_B_2,
"DiT-B/4": DiT_B_4,
"DiT-B/8": DiT_B_8,
"DiT-S/2": DiT_S_2,
"DiT-S/4": DiT_S_4,
"DiT-S/8": DiT_S_8,
}