mirror of
https://github.com/Wan-Video/Wan2.1.git
synced 2025-07-13 19:20:09 +00:00
265 lines
8.8 KiB
Python
265 lines
8.8 KiB
Python
import gc
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import logging
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import math
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import os
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import random
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import sys
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import types
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from contextlib import contextmanager
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from functools import partial
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import numpy as np
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import torch
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import torch.cuda.amp as amp
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import torch.distributed as dist
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import torchvision.transforms.functional as TF
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from tqdm import tqdm
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from wan.distributed.fsdp import shard_model
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from wan.modules.clip import CLIPModel
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from wan.modules.model import WanModel
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from wan.modules.t5 import T5EncoderModel
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from wan.modules.vae import WanVAE
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from wan.utils.fm_solvers import (FlowDPMSolverMultistepScheduler,
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get_sampling_sigmas, retrieve_timesteps)
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from wan.utils.fm_solvers_unipc import FlowUniPCMultistepScheduler
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from wan import WanI2V
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def wan_i2v_generate(self:WanI2V,
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input_prompt,
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img,
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max_area=720 * 1280,
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frame_num=81,
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shift=5.0,
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sample_solver='unipc',
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sampling_steps=40,
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guide_scale=5.0,
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n_prompt="",
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seed=-1,
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offload_model=True):
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r"""
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Generates video frames from input image and text prompt using diffusion process.
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Args:
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input_prompt (`str`):
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Text prompt for content generation.
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img (PIL.Image.Image):
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Input image tensor. Shape: [3, H, W]
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max_area (`int`, *optional*, defaults to 720*1280):
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Maximum pixel area for latent space calculation. Controls video resolution scaling
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frame_num (`int`, *optional*, defaults to 81):
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How many frames to sample from a video. The number should be 4n+1
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shift (`float`, *optional*, defaults to 5.0):
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Noise schedule shift parameter. Affects temporal dynamics
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[NOTE]: If you want to generate a 480p video, it is recommended to set the shift value to 3.0.
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sample_solver (`str`, *optional*, defaults to 'unipc'):
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Solver used to sample the video.
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sampling_steps (`int`, *optional*, defaults to 40):
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Number of diffusion sampling steps. Higher values improve quality but slow generation
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guide_scale (`float`, *optional*, defaults 5.0):
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Classifier-free guidance scale. Controls prompt adherence vs. creativity
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n_prompt (`str`, *optional*, defaults to ""):
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Negative prompt for content exclusion. If not given, use `config.sample_neg_prompt`
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seed (`int`, *optional*, defaults to -1):
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Random seed for noise generation. If -1, use random seed
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offload_model (`bool`, *optional*, defaults to True):
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If True, offloads models to CPU during generation to save VRAM
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Returns:
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torch.Tensor:
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Generated video frames tensor. Dimensions: (C, N H, W) where:
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- C: Color channels (3 for RGB)
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- N: Number of frames (81)
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- H: Frame height (from max_area)
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- W: Frame width from max_area)
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"""
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img = TF.to_tensor(img).sub_(0.5).div_(0.5).to(self.device)
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F = frame_num
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h, w = img.shape[1:]
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aspect_ratio = h / w
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lat_h = round(
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np.sqrt(max_area * aspect_ratio) // self.vae_stride[1] //
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self.patch_size[1] * self.patch_size[1])
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lat_w = round(
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np.sqrt(max_area / aspect_ratio) // self.vae_stride[2] //
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self.patch_size[2] * self.patch_size[2])
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h = lat_h * self.vae_stride[1]
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w = lat_w * self.vae_stride[2]
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max_seq_len = ((F - 1) // self.vae_stride[0] + 1) * lat_h * lat_w // (
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self.patch_size[1] * self.patch_size[2])
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max_seq_len = int(math.ceil(max_seq_len / self.sp_size)) * self.sp_size
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seed = seed if seed >= 0 else random.randint(0, sys.maxsize)
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seed_g = torch.Generator(device=self.device)
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seed_g.manual_seed(seed)
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noise = torch.randn(
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16,
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21,
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lat_h,
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lat_w,
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dtype=torch.float32,
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generator=seed_g,
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device=self.device)
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msk = torch.ones(1, 81, lat_h, lat_w, device=self.device)
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msk[:, 1:] = 0
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msk = torch.concat([
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torch.repeat_interleave(msk[:, 0:1], repeats=4, dim=1), msk[:, 1:]
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],
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dim=1)
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msk = msk.view(1, msk.shape[1] // 4, 4, lat_h, lat_w)
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msk = msk.transpose(1, 2)[0]
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if n_prompt == "":
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n_prompt = self.sample_neg_prompt
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# preprocess
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if not self.t5_cpu:
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self.text_encoder.model.to(self.device)
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context = self.text_encoder([input_prompt], self.device)
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context_null = self.text_encoder([n_prompt], self.device)
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if offload_model:
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self.text_encoder.model.cpu()
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else:
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context = self.text_encoder([input_prompt], torch.device('cpu'))
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context_null = self.text_encoder([n_prompt], torch.device('cpu'))
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context = [t.to(self.device) for t in context]
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context_null = [t.to(self.device) for t in context_null]
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self.clip.model.to(self.device)
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clip_context = self.clip.visual([img[:, None, :, :]])
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if offload_model:
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self.clip.model.cpu()
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y = self.vae.encode([
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torch.concat([
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torch.nn.functional.interpolate(
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img[None].cpu(), size=(h, w), mode='bicubic').transpose(
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0, 1),
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torch.zeros(3, 80, h, w)
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],
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dim=1).to(self.device)
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])[0]
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y = torch.concat([msk, y])
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@contextmanager
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def noop_no_sync():
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yield
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no_sync = getattr(self.model, 'no_sync', noop_no_sync)
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# evaluation mode
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with amp.autocast(dtype=self.param_dtype), torch.no_grad(), no_sync():
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if sample_solver == 'unipc':
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sample_scheduler = FlowUniPCMultistepScheduler(
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num_train_timesteps=self.num_train_timesteps,
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shift=1,
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use_dynamic_shifting=False)
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sample_scheduler.set_timesteps(
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sampling_steps, device=self.device, shift=shift)
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timesteps = sample_scheduler.timesteps
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elif sample_solver == 'dpm++':
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sample_scheduler = FlowDPMSolverMultistepScheduler(
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num_train_timesteps=self.num_train_timesteps,
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shift=1,
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use_dynamic_shifting=False)
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sampling_sigmas = get_sampling_sigmas(sampling_steps, shift)
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timesteps, _ = retrieve_timesteps(
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sample_scheduler,
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device=self.device,
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sigmas=sampling_sigmas)
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else:
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raise NotImplementedError("Unsupported solver.")
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# sample videos
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latent = noise
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arg_c = {
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'context': [context[0]],
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'clip_fea': clip_context,
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'seq_len': max_seq_len,
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'y': [y],
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}
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arg_null = {
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'context': context_null,
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'clip_fea': clip_context,
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'seq_len': max_seq_len,
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'y': [y],
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}
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if offload_model:
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torch.cuda.empty_cache()
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self.model.to(self.device)
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for i, t in enumerate(tqdm(timesteps)):
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current_step = i
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latent_model_input = [latent.to(self.device)]
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timestep = [t]
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timestep = torch.stack(timestep).to(self.device)
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current_stream = 'cond_stream'
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noise_pred_cond = self.model(
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latent_model_input, t=timestep,
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current_step = current_step,
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current_stream = current_stream,
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**arg_c)[0].to(
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torch.device('cpu') if offload_model else self.device)
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if offload_model:
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torch.cuda.empty_cache()
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current_stream = 'uncond_stream'
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noise_pred_uncond = self.model(
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latent_model_input, t=timestep,
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current_step = current_step,
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current_stream = current_stream,
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**arg_null)[0].to(
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torch.device('cpu') if offload_model else self.device)
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if offload_model:
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torch.cuda.empty_cache()
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noise_pred = noise_pred_uncond + guide_scale * (
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noise_pred_cond - noise_pred_uncond)
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latent = latent.to(
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torch.device('cpu') if offload_model else self.device)
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temp_x0 = sample_scheduler.step(
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noise_pred.unsqueeze(0),
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t,
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latent.unsqueeze(0),
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return_dict=False,
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generator=seed_g)[0]
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latent = temp_x0.squeeze(0)
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x0 = [latent.to(self.device)]
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del latent_model_input, timestep
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if offload_model:
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self.model.cpu()
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torch.cuda.empty_cache()
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if self.rank == 0:
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videos = self.vae.decode(x0)
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del noise, latent
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del sample_scheduler
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if offload_model:
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gc.collect()
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torch.cuda.synchronize()
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if dist.is_initialized():
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dist.barrier()
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return videos[0] if self.rank == 0 else None
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