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hao-ai-lab-FastVideo/examples/inference/basic/basic_ltx2.py
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2026-01-20 08:32:06 +00:00

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3.2 KiB
Python

import os
import torch
from transformers import AutoTokenizer
from fastvideo.configs.pipelines import LTX2T2VConfig
from fastvideo.fastvideo_args import FastVideoArgs
from fastvideo.forward_context import set_forward_context
from fastvideo.models.loader.component_loader import (
TextEncoderLoader,
TransformerLoader,
)
def main() -> None:
transformer_path = os.getenv(
"LTX2_FASTVIDEO_PATH", "converted/ltx2/transformer"
)
text_encoder_path = os.getenv(
"LTX2_TEXT_ENCODER_PATH", "converted/ltx2/text_embedding_projection"
)
gemma_model_path = os.getenv("LTX2_GEMMA_MODEL_PATH", "")
if not os.path.isdir(transformer_path):
raise FileNotFoundError(
f"Missing LTX-2 transformer weights at {transformer_path}"
)
if not os.path.isdir(text_encoder_path):
raise FileNotFoundError(
f"Missing LTX-2 text encoder weights at {text_encoder_path}"
)
if not gemma_model_path or not os.path.isdir(gemma_model_path):
raise FileNotFoundError(
"Set LTX2_GEMMA_MODEL_PATH to a local Gemma model directory."
)
os.environ["LTX2_GEMMA_MODEL_PATH"] = gemma_model_path
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
precision = torch.bfloat16
args = FastVideoArgs(
model_path=transformer_path,
pipeline_config=LTX2T2VConfig(),
)
transformer = TransformerLoader().load(transformer_path, args).to(device)
text_encoder = TextEncoderLoader().load(text_encoder_path, args).to(device)
tokenizer = AutoTokenizer.from_pretrained(
gemma_model_path, local_files_only=True
)
tokenizer.padding_side = "left"
if tokenizer.pad_token is None:
tokenizer.pad_token = tokenizer.eos_token
prompt = (
"A curious raccoon peers through a vibrant field of yellow sunflowers."
)
inputs = tokenizer(
prompt,
padding="max_length",
max_length=1024,
truncation=True,
return_tensors="pt",
)
input_ids = inputs["input_ids"].to(device)
attention_mask = inputs["attention_mask"].to(device)
with torch.no_grad():
with set_forward_context(current_timestep=0, attn_metadata=None):
text_outputs = text_encoder(
input_ids=input_ids,
attention_mask=attention_mask,
output_hidden_states=True,
)
prompt_embeds = text_outputs.last_hidden_state.to(
device=device, dtype=precision
)
batch_size = 1
frames = 9
height = 64
width = 64
hidden_states = torch.randn(
batch_size,
transformer.num_channels_latents,
frames,
height,
width,
device=device,
dtype=precision,
)
timestep = torch.tensor([500], device=device, dtype=torch.float32)
with set_forward_context(current_timestep=0, attn_metadata=None):
output = transformer(
hidden_states=hidden_states,
encoder_hidden_states=prompt_embeds,
timestep=timestep,
)
print(f"LTX-2 transformer output shape: {output.shape}")
if __name__ == "__main__":
main()