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			302 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			302 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
# Copyright 2024-2025 The Alibaba Wan Team Authors. All rights reserved.
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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 torch
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import torch.cuda.amp as amp
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import torch.distributed as dist
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from tqdm import tqdm
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from .distributed.fsdp import shard_model
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from .modules.model import WanModel
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from .modules.t5 import T5EncoderModel
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from .modules.vae import WanVAE
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from .utils.fm_solvers import (FlowDPMSolverMultistepScheduler,
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                               get_sampling_sigmas, retrieve_timesteps)
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from .utils.fm_solvers_unipc import FlowUniPCMultistepScheduler
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class WanT2V:
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    def __init__(
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        self,
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        config,
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        checkpoint_dir,
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        device_id=0,
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        rank=0,
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        t5_fsdp=False,
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        dit_fsdp=False,
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        use_usp=False,
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        t5_cpu=False,
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        model_filename = None,
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        text_encoder_filename = None
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    ):
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        r"""
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        Initializes the Wan text-to-video generation model components.
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        Args:
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            config (EasyDict):
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                Object containing model parameters initialized from config.py
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            checkpoint_dir (`str`):
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                Path to directory containing model checkpoints
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            device_id (`int`,  *optional*, defaults to 0):
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                Id of target GPU device
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            rank (`int`,  *optional*, defaults to 0):
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                Process rank for distributed training
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            t5_fsdp (`bool`, *optional*, defaults to False):
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                Enable FSDP sharding for T5 model
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            dit_fsdp (`bool`, *optional*, defaults to False):
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                Enable FSDP sharding for DiT model
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            use_usp (`bool`, *optional*, defaults to False):
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                Enable distribution strategy of USP.
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            t5_cpu (`bool`, *optional*, defaults to False):
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                Whether to place T5 model on CPU. Only works without t5_fsdp.
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        """
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        self.device = torch.device(f"cuda:{device_id}")
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        self.config = config
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        self.rank = rank
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        self.t5_cpu = t5_cpu
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        self.num_train_timesteps = config.num_train_timesteps
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        self.param_dtype = config.param_dtype
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        shard_fn = partial(shard_model, device_id=device_id)
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        self.text_encoder = T5EncoderModel(
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            text_len=config.text_len,
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            dtype=config.t5_dtype,
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            device=torch.device('cpu'),
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            checkpoint_path=text_encoder_filename,
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            tokenizer_path=os.path.join(checkpoint_dir, config.t5_tokenizer),
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            shard_fn=shard_fn if t5_fsdp else None)
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        self.vae_stride = config.vae_stride
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        self.patch_size = config.patch_size
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        self.vae = WanVAE(
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            vae_pth=os.path.join(checkpoint_dir, config.vae_checkpoint),
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            device=self.device)
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        logging.info(f"Creating WanModel from {model_filename}")
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        from mmgp import offload
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        self.model = offload.fast_load_transformers_model(model_filename, modelClass=WanModel)
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        self.model.eval().requires_grad_(False)
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        if use_usp:
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            from xfuser.core.distributed import \
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                get_sequence_parallel_world_size
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            from .distributed.xdit_context_parallel import (usp_attn_forward,
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                                                            usp_dit_forward)
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            for block in self.model.blocks:
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                block.self_attn.forward = types.MethodType(
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                    usp_attn_forward, block.self_attn)
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            self.model.forward = types.MethodType(usp_dit_forward, self.model)
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            self.sp_size = get_sequence_parallel_world_size()
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        else:
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            self.sp_size = 1
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        # if dist.is_initialized():
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        #     dist.barrier()
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        # if dit_fsdp:
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        #     self.model = shard_fn(self.model)
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        # else:
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        #     self.model.to(self.device)
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        self.sample_neg_prompt = config.sample_neg_prompt
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    def generate(self,
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                 input_prompt,
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                 size=(1280, 720),
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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=50,
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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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                 callback = None,
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                 enable_RIFLEx = None
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                 ):
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        r"""
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        Generates video frames from 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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            size (tupele[`int`], *optional*, defaults to (1280,720)):
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                Controls video resolution, (width,height).
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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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            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 size)
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                - W: Frame width from size)
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        """
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        # preprocess
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        F = frame_num
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        target_shape = (self.vae.model.z_dim, (F - 1) // self.vae_stride[0] + 1,
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                        size[1] // self.vae_stride[1],
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                        size[0] // self.vae_stride[2])
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        seq_len = math.ceil((target_shape[2] * target_shape[3]) /
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                            (self.patch_size[1] * self.patch_size[2]) *
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                            target_shape[1] / self.sp_size) * self.sp_size
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        if n_prompt == "":
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            n_prompt = self.sample_neg_prompt
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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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        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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        noise = [
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            torch.randn(
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                target_shape[0],
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                target_shape[1],
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                target_shape[2],
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                target_shape[3],
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                dtype=torch.float32,
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                device=self.device,
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                generator=seed_g)
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        ]
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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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        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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        latents = noise
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        # from .modules.model import identify_k
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        # for nf in range(20, 50):
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        #     k, N_k = identify_k(10000, 44, 26)
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        #     print(f"value nb latent frames={nf}, k={k}, n_k={N_k}")
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        freqs = self.model.get_rope_freqs(nb_latent_frames = int((frame_num - 1)/4 + 1), RIFLEx_k = 4 if enable_RIFLEx else None )
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        arg_c = {'context': context, 'seq_len': seq_len, 'freqs': freqs, 'pipeline': self}
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        arg_null = {'context': context_null, 'seq_len': seq_len, 'freqs': freqs, 'pipeline': self}
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        if callback != None:
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            callback(-1, None)
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        self._interrupt = False
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        for i, t in enumerate(tqdm(timesteps)):
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            latent_model_input = latents
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            timestep = [t]
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            timestep = torch.stack(timestep)
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            # self.model.to(self.device)
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            noise_pred_cond = self.model(
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                latent_model_input, t=timestep, **arg_c)[0]
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            if self._interrupt:
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                return None               
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            noise_pred_uncond = self.model(
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                latent_model_input, t=timestep, **arg_null)[0]
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            if self._interrupt:
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                return None
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            del latent_model_input
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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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            del noise_pred_uncond
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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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                latents[0].unsqueeze(0),
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                return_dict=False,
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                generator=seed_g)[0]
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            latents = [temp_x0.squeeze(0)]
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            del temp_x0
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            if callback is not None:
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                callback(i, latents)         
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        x0 = latents
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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, latents
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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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