DreamCraft3D/threestudio/models/guidance/stable_diffusion_unified_guidance.py
2023-12-15 17:44:44 +08:00

730 lines
28 KiB
Python

import random
from contextlib import contextmanager
from dataclasses import dataclass, field
import torch
import torch.nn as nn
import torch.nn.functional as F
from diffusers import (
AutoencoderKL,
ControlNetModel,
DDPMScheduler,
DPMSolverSinglestepScheduler,
StableDiffusionPipeline,
UNet2DConditionModel,
)
from diffusers.loaders import AttnProcsLayers
from diffusers.models.attention_processor import LoRAAttnProcessor
from diffusers.models.embeddings import TimestepEmbedding
from diffusers.utils.import_utils import is_xformers_available
from tqdm import tqdm
import threestudio
from threestudio.models.networks import ToDTypeWrapper
from threestudio.models.prompt_processors.base import PromptProcessorOutput
from threestudio.utils.base import BaseModule
from threestudio.utils.misc import C, cleanup, enable_gradient, parse_version
from threestudio.utils.ops import perpendicular_component
from threestudio.utils.typing import *
@threestudio.register("stable-diffusion-unified-guidance")
class StableDiffusionUnifiedGuidance(BaseModule):
@dataclass
class Config(BaseModule.Config):
cache_dir: Optional[str] = None
local_files_only: Optional[bool] = False
# guidance type, in ["sds", "vsd"]
guidance_type: str = "sds"
pretrained_model_name_or_path: str = "runwayml/stable-diffusion-v1-5"
guidance_scale: float = 100.0
weighting_strategy: str = "dreamfusion"
view_dependent_prompting: bool = True
min_step_percent: Any = 0.02
max_step_percent: Any = 0.98
grad_clip: Optional[Any] = None
return_rgb_1step_orig: bool = False
return_rgb_multistep_orig: bool = False
n_rgb_multistep_orig_steps: int = 4
# TODO
# controlnet
controlnet_model_name_or_path: Optional[str] = None
preprocessor: Optional[str] = None
control_scale: float = 1.0
# TODO
# lora
lora_model_name_or_path: Optional[str] = None
# efficiency-related configurations
half_precision_weights: bool = True
enable_memory_efficient_attention: bool = False
enable_sequential_cpu_offload: bool = False
enable_attention_slicing: bool = False
enable_channels_last_format: bool = False
token_merging: bool = False
token_merging_params: Optional[dict] = field(default_factory=dict)
# VSD configurations, only used when guidance_type is "vsd"
vsd_phi_model_name_or_path: Optional[str] = None
vsd_guidance_scale_phi: float = 1.0
vsd_use_lora: bool = True
vsd_lora_cfg_training: bool = False
vsd_lora_n_timestamp_samples: int = 1
vsd_use_camera_condition: bool = True
# camera condition type, in ["extrinsics", "mvp", "spherical"]
vsd_camera_condition_type: Optional[str] = "extrinsics"
cfg: Config
def configure(self) -> None:
self.min_step: Optional[int] = None
self.max_step: Optional[int] = None
self.grad_clip_val: Optional[float] = None
@dataclass
class NonTrainableModules:
pipe: StableDiffusionPipeline
pipe_phi: Optional[StableDiffusionPipeline] = None
controlnet: Optional[ControlNetModel] = None
self.weights_dtype = (
torch.float16 if self.cfg.half_precision_weights else torch.float32
)
threestudio.info(f"Loading Stable Diffusion ...")
pipe_kwargs = {
"tokenizer": None,
"safety_checker": None,
"feature_extractor": None,
"requires_safety_checker": False,
"torch_dtype": self.weights_dtype,
"cache_dir": self.cfg.cache_dir,
"local_files_only": self.cfg.local_files_only,
}
pipe = StableDiffusionPipeline.from_pretrained(
self.cfg.pretrained_model_name_or_path,
**pipe_kwargs,
).to(self.device)
self.prepare_pipe(pipe)
self.configure_pipe_token_merging(pipe)
# phi network for VSD
# introduce two trainable modules:
# - self.camera_embedding
# - self.lora_layers
pipe_phi = None
# if the phi network shares the same unet with the pretrain network
# we need to pass additional cross attention kwargs to the unet
self.vsd_share_model = (
self.cfg.guidance_type == "vsd"
and self.cfg.vsd_phi_model_name_or_path is None
)
if self.cfg.guidance_type == "vsd":
if self.cfg.vsd_phi_model_name_or_path is None:
pipe_phi = pipe
else:
pipe_phi = StableDiffusionPipeline.from_pretrained(
self.cfg.vsd_phi_model_name_or_path,
**pipe_kwargs,
).to(self.device)
self.prepare_pipe(pipe_phi)
self.configure_pipe_token_merging(pipe_phi)
# set up camera embedding
if self.cfg.vsd_use_camera_condition:
if self.cfg.vsd_camera_condition_type in ["extrinsics", "mvp"]:
self.camera_embedding_dim = 16
elif self.cfg.vsd_camera_condition_type == "spherical":
self.camera_embedding_dim = 4
else:
raise ValueError("Invalid camera condition type!")
# FIXME: hard-coded output dim
self.camera_embedding = ToDTypeWrapper(
TimestepEmbedding(self.camera_embedding_dim, 1280),
self.weights_dtype,
).to(self.device)
pipe_phi.unet.class_embedding = self.camera_embedding
if self.cfg.vsd_use_lora:
# set up LoRA layers
lora_attn_procs = {}
for name in pipe_phi.unet.attn_processors.keys():
cross_attention_dim = (
None
if name.endswith("attn1.processor")
else pipe_phi.unet.config.cross_attention_dim
)
if name.startswith("mid_block"):
hidden_size = pipe_phi.unet.config.block_out_channels[-1]
elif name.startswith("up_blocks"):
block_id = int(name[len("up_blocks.")])
hidden_size = list(
reversed(pipe_phi.unet.config.block_out_channels)
)[block_id]
elif name.startswith("down_blocks"):
block_id = int(name[len("down_blocks.")])
hidden_size = pipe_phi.unet.config.block_out_channels[block_id]
lora_attn_procs[name] = LoRAAttnProcessor(
hidden_size=hidden_size, cross_attention_dim=cross_attention_dim
)
pipe_phi.unet.set_attn_processor(lora_attn_procs)
self.lora_layers = AttnProcsLayers(pipe_phi.unet.attn_processors).to(
self.device
)
self.lora_layers._load_state_dict_pre_hooks.clear()
self.lora_layers._state_dict_hooks.clear()
threestudio.info(f"Loaded Stable Diffusion!")
# controlnet
controlnet = None
if self.cfg.controlnet_model_name_or_path is not None:
threestudio.info(f"Loading ControlNet ...")
controlnet = ControlNetModel.from_pretrained(
self.cfg.controlnet_model_name_or_path,
torch_dtype=self.weights_dtype,
).to(self.device)
controlnet.eval()
enable_gradient(controlnet, enabled=False)
threestudio.info(f"Loaded ControlNet!")
self.scheduler = DDPMScheduler.from_config(pipe.scheduler.config)
self.num_train_timesteps = self.scheduler.config.num_train_timesteps
# q(z_t|x) = N(alpha_t x, sigma_t^2 I)
# in DDPM, alpha_t = sqrt(alphas_cumprod_t), sigma_t^2 = 1 - alphas_cumprod_t
self.alphas_cumprod: Float[Tensor, "T"] = self.scheduler.alphas_cumprod.to(
self.device
)
self.alphas: Float[Tensor, "T"] = self.alphas_cumprod**0.5
self.sigmas: Float[Tensor, "T"] = (1 - self.alphas_cumprod) ** 0.5
# log SNR
self.lambdas: Float[Tensor, "T"] = self.sigmas / self.alphas
self._non_trainable_modules = NonTrainableModules(
pipe=pipe,
pipe_phi=pipe_phi,
controlnet=controlnet,
)
@property
def pipe(self) -> StableDiffusionPipeline:
return self._non_trainable_modules.pipe
@property
def pipe_phi(self) -> StableDiffusionPipeline:
if self._non_trainable_modules.pipe_phi is None:
raise RuntimeError("phi model is not available.")
return self._non_trainable_modules.pipe_phi
@property
def controlnet(self) -> ControlNetModel:
if self._non_trainable_modules.controlnet is None:
raise RuntimeError("ControlNet model is not available.")
return self._non_trainable_modules.controlnet
def prepare_pipe(self, pipe: StableDiffusionPipeline):
if self.cfg.enable_memory_efficient_attention:
if parse_version(torch.__version__) >= parse_version("2"):
threestudio.info(
"PyTorch2.0 uses memory efficient attention by default."
)
elif not is_xformers_available():
threestudio.warn(
"xformers is not available, memory efficient attention is not enabled."
)
else:
pipe.enable_xformers_memory_efficient_attention()
if self.cfg.enable_sequential_cpu_offload:
pipe.enable_sequential_cpu_offload()
if self.cfg.enable_attention_slicing:
pipe.enable_attention_slicing(1)
if self.cfg.enable_channels_last_format:
pipe.unet.to(memory_format=torch.channels_last)
# FIXME: pipe.__call__ requires text_encoder.dtype
# pipe.text_encoder.to("meta")
cleanup()
pipe.vae.eval()
pipe.unet.eval()
enable_gradient(pipe.vae, enabled=False)
enable_gradient(pipe.unet, enabled=False)
# disable progress bar
pipe.set_progress_bar_config(disable=True)
def configure_pipe_token_merging(self, pipe: StableDiffusionPipeline):
if self.cfg.token_merging:
import tomesd
tomesd.apply_patch(pipe.unet, **self.cfg.token_merging_params)
@torch.cuda.amp.autocast(enabled=False)
def forward_unet(
self,
unet: UNet2DConditionModel,
latents: Float[Tensor, "..."],
t: Int[Tensor, "..."],
encoder_hidden_states: Float[Tensor, "..."],
class_labels: Optional[Float[Tensor, "..."]] = None,
cross_attention_kwargs: Optional[Dict[str, Any]] = None,
down_block_additional_residuals: Optional[Float[Tensor, "..."]] = None,
mid_block_additional_residual: Optional[Float[Tensor, "..."]] = None,
velocity_to_epsilon: bool = False,
) -> Float[Tensor, "..."]:
input_dtype = latents.dtype
pred = unet(
latents.to(unet.dtype),
t.to(unet.dtype),
encoder_hidden_states=encoder_hidden_states.to(unet.dtype),
class_labels=class_labels,
cross_attention_kwargs=cross_attention_kwargs,
down_block_additional_residuals=down_block_additional_residuals,
mid_block_additional_residual=mid_block_additional_residual,
).sample
if velocity_to_epsilon:
pred = latents * self.sigmas[t].view(-1, 1, 1, 1) + pred * self.alphas[
t
].view(-1, 1, 1, 1)
return pred.to(input_dtype)
@torch.cuda.amp.autocast(enabled=False)
def vae_encode(
self, vae: AutoencoderKL, imgs: Float[Tensor, "B 3 H W"], mode=False
) -> Float[Tensor, "B 4 Hl Wl"]:
# expect input in [-1, 1]
input_dtype = imgs.dtype
posterior = vae.encode(imgs.to(vae.dtype)).latent_dist
if mode:
latents = posterior.mode()
else:
latents = posterior.sample()
latents = latents * vae.config.scaling_factor
return latents.to(input_dtype)
@torch.cuda.amp.autocast(enabled=False)
def vae_decode(
self, vae: AutoencoderKL, latents: Float[Tensor, "B 4 Hl Wl"]
) -> Float[Tensor, "B 3 H W"]:
# output in [0, 1]
input_dtype = latents.dtype
latents = 1 / vae.config.scaling_factor * latents
image = vae.decode(latents.to(vae.dtype)).sample
image = (image * 0.5 + 0.5).clamp(0, 1)
return image.to(input_dtype)
@contextmanager
def disable_unet_class_embedding(self, unet: UNet2DConditionModel):
class_embedding = unet.class_embedding
try:
unet.class_embedding = None
yield unet
finally:
unet.class_embedding = class_embedding
@contextmanager
def set_scheduler(
self, pipe: StableDiffusionPipeline, scheduler_class: Any, **kwargs
):
scheduler_orig = pipe.scheduler
pipe.scheduler = scheduler_class.from_config(scheduler_orig.config, **kwargs)
yield pipe
pipe.scheduler = scheduler_orig
def get_eps_pretrain(
self,
latents_noisy: Float[Tensor, "B 4 Hl Wl"],
t: Int[Tensor, "B"],
prompt_utils: PromptProcessorOutput,
elevation: Float[Tensor, "B"],
azimuth: Float[Tensor, "B"],
camera_distances: Float[Tensor, "B"],
) -> Float[Tensor, "B 4 Hl Wl"]:
batch_size = latents_noisy.shape[0]
if prompt_utils.use_perp_neg:
(
text_embeddings,
neg_guidance_weights,
) = prompt_utils.get_text_embeddings_perp_neg(
elevation, azimuth, camera_distances, self.cfg.view_dependent_prompting
)
with torch.no_grad():
with self.disable_unet_class_embedding(self.pipe.unet) as unet:
noise_pred = self.forward_unet(
unet,
torch.cat([latents_noisy] * 4, dim=0),
torch.cat([t] * 4, dim=0),
encoder_hidden_states=text_embeddings,
cross_attention_kwargs={"scale": 0.0}
if self.vsd_share_model
else None,
velocity_to_epsilon=self.pipe.scheduler.config.prediction_type
== "v_prediction",
) # (4B, 3, Hl, Wl)
noise_pred_text = noise_pred[:batch_size]
noise_pred_uncond = noise_pred[batch_size : batch_size * 2]
noise_pred_neg = noise_pred[batch_size * 2 :]
e_pos = noise_pred_text - noise_pred_uncond
accum_grad = 0
n_negative_prompts = neg_guidance_weights.shape[-1]
for i in range(n_negative_prompts):
e_i_neg = noise_pred_neg[i::n_negative_prompts] - noise_pred_uncond
accum_grad += neg_guidance_weights[:, i].view(
-1, 1, 1, 1
) * perpendicular_component(e_i_neg, e_pos)
noise_pred = noise_pred_uncond + self.cfg.guidance_scale * (
e_pos + accum_grad
)
else:
text_embeddings = prompt_utils.get_text_embeddings(
elevation, azimuth, camera_distances, self.cfg.view_dependent_prompting
)
with torch.no_grad():
with self.disable_unet_class_embedding(self.pipe.unet) as unet:
noise_pred = self.forward_unet(
unet,
torch.cat([latents_noisy] * 2, dim=0),
torch.cat([t] * 2, dim=0),
encoder_hidden_states=text_embeddings,
cross_attention_kwargs={"scale": 0.0}
if self.vsd_share_model
else None,
velocity_to_epsilon=self.pipe.scheduler.config.prediction_type
== "v_prediction",
)
noise_pred_text, noise_pred_uncond = noise_pred.chunk(2)
noise_pred = noise_pred_uncond + self.cfg.guidance_scale * (
noise_pred_text - noise_pred_uncond
)
return noise_pred
def get_eps_phi(
self,
latents_noisy: Float[Tensor, "B 4 Hl Wl"],
t: Int[Tensor, "B"],
prompt_utils: PromptProcessorOutput,
elevation: Float[Tensor, "B"],
azimuth: Float[Tensor, "B"],
camera_distances: Float[Tensor, "B"],
camera_condition: Float[Tensor, "B ..."],
) -> Float[Tensor, "B 4 Hl Wl"]:
batch_size = latents_noisy.shape[0]
# not using view-dependent prompting in LoRA
text_embeddings, _ = prompt_utils.get_text_embeddings(
elevation, azimuth, camera_distances, view_dependent_prompting=False
).chunk(2)
with torch.no_grad():
noise_pred = self.forward_unet(
self.pipe_phi.unet,
torch.cat([latents_noisy] * 2, dim=0),
torch.cat([t] * 2, dim=0),
encoder_hidden_states=torch.cat([text_embeddings] * 2, dim=0),
class_labels=torch.cat(
[
camera_condition.view(batch_size, -1),
torch.zeros_like(camera_condition.view(batch_size, -1)),
],
dim=0,
)
if self.cfg.vsd_use_camera_condition
else None,
cross_attention_kwargs={"scale": 1.0},
velocity_to_epsilon=self.pipe_phi.scheduler.config.prediction_type
== "v_prediction",
)
noise_pred_camera, noise_pred_uncond = noise_pred.chunk(2)
noise_pred = noise_pred_uncond + self.cfg.vsd_guidance_scale_phi * (
noise_pred_camera - noise_pred_uncond
)
return noise_pred
def train_phi(
self,
latents: Float[Tensor, "B 4 Hl Wl"],
prompt_utils: PromptProcessorOutput,
elevation: Float[Tensor, "B"],
azimuth: Float[Tensor, "B"],
camera_distances: Float[Tensor, "B"],
camera_condition: Float[Tensor, "B ..."],
):
B = latents.shape[0]
latents = latents.detach().repeat(
self.cfg.vsd_lora_n_timestamp_samples, 1, 1, 1
)
num_train_timesteps = self.pipe_phi.scheduler.config.num_train_timesteps
t = torch.randint(
int(num_train_timesteps * 0.0),
int(num_train_timesteps * 1.0),
[B * self.cfg.vsd_lora_n_timestamp_samples],
dtype=torch.long,
device=self.device,
)
noise = torch.randn_like(latents)
latents_noisy = self.pipe_phi.scheduler.add_noise(latents, noise, t)
if self.pipe_phi.scheduler.config.prediction_type == "epsilon":
target = noise
elif self.pipe_phi.scheduler.prediction_type == "v_prediction":
target = self.pipe_phi.scheduler.get_velocity(latents, noise, t)
else:
raise ValueError(
f"Unknown prediction type {self.pipe_phi.scheduler.prediction_type}"
)
# not using view-dependent prompting in LoRA
text_embeddings, _ = prompt_utils.get_text_embeddings(
elevation, azimuth, camera_distances, view_dependent_prompting=False
).chunk(2)
if (
self.cfg.vsd_use_camera_condition
and self.cfg.vsd_lora_cfg_training
and random.random() < 0.1
):
camera_condition = torch.zeros_like(camera_condition)
noise_pred = self.forward_unet(
self.pipe_phi.unet,
latents_noisy,
t,
encoder_hidden_states=text_embeddings.repeat(
self.cfg.vsd_lora_n_timestamp_samples, 1, 1
),
class_labels=camera_condition.view(B, -1).repeat(
self.cfg.vsd_lora_n_timestamp_samples, 1
)
if self.cfg.vsd_use_camera_condition
else None,
cross_attention_kwargs={"scale": 1.0},
)
return F.mse_loss(noise_pred.float(), target.float(), reduction="mean")
def forward(
self,
rgb: Float[Tensor, "B H W C"],
prompt_utils: PromptProcessorOutput,
elevation: Float[Tensor, "B"],
azimuth: Float[Tensor, "B"],
camera_distances: Float[Tensor, "B"],
mvp_mtx: Float[Tensor, "B 4 4"],
c2w: Float[Tensor, "B 4 4"],
rgb_as_latents=False,
**kwargs,
):
batch_size = rgb.shape[0]
rgb_BCHW = rgb.permute(0, 3, 1, 2)
latents: Float[Tensor, "B 4 Hl Wl"]
if rgb_as_latents:
# treat input rgb as latents
# input rgb should be in range [-1, 1]
latents = F.interpolate(
rgb_BCHW, (64, 64), mode="bilinear", align_corners=False
)
else:
# treat input rgb as rgb
# input rgb should be in range [0, 1]
rgb_BCHW = F.interpolate(
rgb_BCHW, (512, 512), mode="bilinear", align_corners=False
)
# encode image into latents with vae
latents = self.vae_encode(self.pipe.vae, rgb_BCHW * 2.0 - 1.0)
# sample timestep
# use the same timestep for each batch
assert self.min_step is not None and self.max_step is not None
t = torch.randint(
self.min_step,
self.max_step + 1,
[1],
dtype=torch.long,
device=self.device,
).repeat(batch_size)
# sample noise
noise = torch.randn_like(latents)
latents_noisy = self.scheduler.add_noise(latents, noise, t)
eps_pretrain = self.get_eps_pretrain(
latents_noisy, t, prompt_utils, elevation, azimuth, camera_distances
)
latents_1step_orig = (
1
/ self.alphas[t].view(-1, 1, 1, 1)
* (latents_noisy - self.sigmas[t].view(-1, 1, 1, 1) * eps_pretrain)
).detach()
if self.cfg.guidance_type == "sds":
eps_phi = noise
elif self.cfg.guidance_type == "vsd":
if self.cfg.vsd_camera_condition_type == "extrinsics":
camera_condition = c2w
elif self.cfg.vsd_camera_condition_type == "mvp":
camera_condition = mvp_mtx
elif self.cfg.vsd_camera_condition_type == "spherical":
camera_condition = torch.stack(
[
torch.deg2rad(elevation),
torch.sin(torch.deg2rad(azimuth)),
torch.cos(torch.deg2rad(azimuth)),
camera_distances,
],
dim=-1,
)
else:
raise ValueError(
f"Unknown camera_condition_type {self.cfg.vsd_camera_condition_type}"
)
eps_phi = self.get_eps_phi(
latents_noisy,
t,
prompt_utils,
elevation,
azimuth,
camera_distances,
camera_condition,
)
loss_train_phi = self.train_phi(
latents,
prompt_utils,
elevation,
azimuth,
camera_distances,
camera_condition,
)
if self.cfg.weighting_strategy == "dreamfusion":
w = (1.0 - self.alphas[t]).view(-1, 1, 1, 1)
elif self.cfg.weighting_strategy == "uniform":
w = 1.0
elif self.cfg.weighting_strategy == "fantasia3d":
w = (self.alphas[t] ** 0.5 * (1 - self.alphas[t])).view(-1, 1, 1, 1)
else:
raise ValueError(
f"Unknown weighting strategy: {self.cfg.weighting_strategy}"
)
grad = w * (eps_pretrain - eps_phi)
if self.grad_clip_val is not None:
grad = grad.clamp(-self.grad_clip_val, self.grad_clip_val)
# reparameterization trick:
# d(loss)/d(latents) = latents - target = latents - (latents - grad) = grad
target = (latents - grad).detach()
loss_sd = 0.5 * F.mse_loss(latents, target, reduction="sum") / batch_size
guidance_out = {
"loss_sd": loss_sd,
"grad_norm": grad.norm(),
"timesteps": t,
"min_step": self.min_step,
"max_step": self.max_step,
"latents": latents,
"latents_1step_orig": latents_1step_orig,
"rgb": rgb_BCHW.permute(0, 2, 3, 1),
"weights": w,
"lambdas": self.lambdas[t],
}
if self.cfg.return_rgb_1step_orig:
with torch.no_grad():
rgb_1step_orig = self.vae_decode(
self.pipe.vae, latents_1step_orig
).permute(0, 2, 3, 1)
guidance_out.update({"rgb_1step_orig": rgb_1step_orig})
if self.cfg.return_rgb_multistep_orig:
with self.set_scheduler(
self.pipe,
DPMSolverSinglestepScheduler,
solver_order=1,
num_train_timesteps=int(t[0]),
) as pipe:
text_embeddings = prompt_utils.get_text_embeddings(
elevation,
azimuth,
camera_distances,
self.cfg.view_dependent_prompting,
)
text_embeddings_cond, text_embeddings_uncond = text_embeddings.chunk(2)
with torch.cuda.amp.autocast(enabled=False):
latents_multistep_orig = pipe(
num_inference_steps=self.cfg.n_rgb_multistep_orig_steps,
guidance_scale=self.cfg.guidance_scale,
eta=1.0,
latents=latents_noisy.to(pipe.unet.dtype),
prompt_embeds=text_embeddings_cond.to(pipe.unet.dtype),
negative_prompt_embeds=text_embeddings_uncond.to(
pipe.unet.dtype
),
cross_attention_kwargs={"scale": 0.0}
if self.vsd_share_model
else None,
output_type="latent",
).images.to(latents.dtype)
with torch.no_grad():
rgb_multistep_orig = self.vae_decode(
self.pipe.vae, latents_multistep_orig
)
guidance_out.update(
{
"latents_multistep_orig": latents_multistep_orig,
"rgb_multistep_orig": rgb_multistep_orig.permute(0, 2, 3, 1),
}
)
if self.cfg.guidance_type == "vsd":
guidance_out.update(
{
"loss_train_phi": loss_train_phi,
}
)
return guidance_out
def update_step(self, epoch: int, global_step: int, on_load_weights: bool = False):
# clip grad for stable training as demonstrated in
# Debiasing Scores and Prompts of 2D Diffusion for Robust Text-to-3D Generation
# http://arxiv.org/abs/2303.15413
if self.cfg.grad_clip is not None:
self.grad_clip_val = C(self.cfg.grad_clip, epoch, global_step)
self.min_step = int(
self.num_train_timesteps * C(self.cfg.min_step_percent, epoch, global_step)
)
self.max_step = int(
self.num_train_timesteps * C(self.cfg.max_step_percent, epoch, global_step)
)