FastVideo is a lightweight framework for accelerating large video diffusion models.

🤗 FastHunyuan | 🤗 FastMochi | 🟣💬 Slack

repo-demo.mp4

FastVideo currently offers: (with more to come)

• [NEW!] Sliding Tile Attention.
• FastHunyuan and FastMochi: consistency distilled video diffusion models for 8x inference speedup.
• First open distillation recipes for video DiT, based on PCM.
• Support distilling/finetuning/inferencing state-of-the-art open video DiTs: 1. Mochi 2. Hunyuan.
• Scalable training with FSDP, sequence parallelism, and selective activation checkpointing, with near linear scaling to 64 GPUs.
• Memory efficient finetuning with LoRA, precomputed latent, and precomputed text embeddings.

Dev in progress and highly experimental.

Change Log

• 2025/02/20: FastVideo now supports STA on StepVideo with 3.4X speedup!
• 2025/02/18: Release the inference code and kernel for Sliding Tile Attention.
• 2025/01/13: Support Lora finetuning for HunyuanVideo.
• 2024/12/25: Enable single 4090 inference for FastHunyuan, please rerun the installation steps to update the environment.
• 2024/12/17: FastVideo v1.0 is released.

🔧 Installation

The code is tested on Python 3.10.0, CUDA 12.4 and H100.

./env_setup.sh fastvideo

To try Sliding Tile Attention (optional), please follow the instruction in csrc/sliding_tile_attention/README.md to install STA.

🚀 Inference

Inference StepVideo with Sliding Tile Attention

First, download the model:

python scripts/huggingface/download_hf.py --repo_id=stepfun-ai/stepvideo-t2v --local_dir=data/stepvideo-t2v --repo_type=model 

Use the following scripts to run inference for StepVideo. When using STA for inference, the generated videos will have dimensions of 204×768×768 (currently, this is the only supported shape).

sh scripts/inference/inference_stepvideo_STA.sh # Inference stepvideo with STA
sh scripts/inference/inference_stepvideo.sh # Inference original stepvideo

Inference HunyuanVideo with Sliding Tile Attention

First, download the model:

python scripts/huggingface/download_hf.py --repo_id=FastVideo/hunyuan --local_dir=data/hunyuan --repo_type=model 

We provide two examples in the following script to run inference with STA + TeaCache and STA only.

sh scripts/inference/inference_hunyuan_STA.sh

Video Demos using STA + Teacache

Visit our demo website to explore our complete collection of examples. We shorten a single video generation process from 945s to 317s on H100.

Inference FastHunyuan on single RTX4090

We now support NF4 and LLM-INT8 quantized inference using BitsAndBytes for FastHunyuan. With NF4 quantization, inference can be performed on a single RTX 4090 GPU, requiring just 20GB of VRAM.

# Download the model weight
python scripts/huggingface/download_hf.py --repo_id=FastVideo/FastHunyuan-diffusers --local_dir=data/FastHunyuan-diffusers --repo_type=model
# CLI inference
bash scripts/inference/inference_hunyuan_hf_quantization.sh

For more information about the VRAM requirements for BitsAndBytes quantization, please refer to the table below (timing measured on an H100 GPU):

Configuration	Memory to Init Transformer	Peak Memory After Init Pipeline (Denoise)	Diffusion Time	End-to-End Time
BF16 + Pipeline CPU Offload	23.883G	33.744G	81s	121.5s
INT8 + Pipeline CPU Offload	13.911G	27.979G	88s	116.7s
NF4 + Pipeline CPU Offload	9.453G	19.26G	78s	114.5s

For improved quality in generated videos, we recommend using a GPU with 80GB of memory to run the BF16 model with the original Hunyuan pipeline. To execute the inference, use the following section:

FastHunyuan

# Download the model weight
python scripts/huggingface/download_hf.py --repo_id=FastVideo/FastHunyuan --local_dir=data/FastHunyuan --repo_type=model
# CLI inference
bash scripts/inference/inference_hunyuan.sh

You can also inference FastHunyuan in the official Hunyuan github.

FastMochi

# Download the model weight
python scripts/huggingface/download_hf.py --repo_id=FastVideo/FastMochi-diffusers --local_dir=data/FastMochi-diffusers --repo_type=model
# CLI inference
bash scripts/inference/inference_mochi_sp.sh

🎯 Distill

Our distillation recipe is based on Phased Consistency Model. We did not find significant improvement using multi-phase distillation, so we keep the one phase setup similar to the original latent consistency model's recipe. We use the MixKit dataset for distillation. To avoid running the text encoder and VAE during training, we preprocess all data to generate text embeddings and VAE latents. Preprocessing instructions can be found data_preprocess.md. For convenience, we also provide preprocessed data that can be downloaded directly using the following command:

python scripts/huggingface/download_hf.py --repo_id=FastVideo/HD-Mixkit-Finetune-Hunyuan --local_dir=data/HD-Mixkit-Finetune-Hunyuan --repo_type=dataset

Next, download the original model weights with:

python scripts/huggingface/download_hf.py --repo_id=FastVideo/hunyuan --local_dir=data/hunyuan --repo_type=model # original hunyuan
python scripts/huggingface/download_hf.py --repo_id=genmo/mochi-1-preview --local_dir=data/mochi --repo_type=model # original mochi

To launch the distillation process, use the following commands:

bash scripts/distill/distill_hunyuan.sh # for hunyuan
bash scripts/distill/distill_mochi.sh # for mochi

We also provide an optional script for distillation with adversarial loss, located at fastvideo/distill_adv.py. Although we tried adversarial loss, we did not observe significant improvements.

Finetune

⚡ Full Finetune

Ensure your data is prepared and preprocessed in the format specified in data_preprocess.md. For convenience, we also provide a mochi preprocessed Black Myth Wukong data that can be downloaded directly:

python scripts/huggingface/download_hf.py --repo_id=FastVideo/Mochi-Black-Myth --local_dir=data/Mochi-Black-Myth --repo_type=dataset

Download the original model weights as specified in Distill Section:

Then you can run the finetune with:

bash scripts/finetune/finetune_mochi.sh # for mochi

Note that for finetuning, we did not tune the hyperparameters in the provided script.

⚡ Lora Finetune

Hunyuan supports Lora fine-tuning of videos up to 720p. Demos and prompts of Black-Myth-Wukong can be found in here. You can download the Lora weight through:

python scripts/huggingface/download_hf.py --repo_id=FastVideo/Hunyuan-Black-Myth-Wukong-lora-weight --local_dir=data/Hunyuan-Black-Myth-Wukong-lora-weight --repo_type=model

Minimum Hardware Requirement

• 40 GB GPU memory each for 2 GPUs with lora.
• 30 GB GPU memory each for 2 GPUs with CPU offload and lora.

Currently, both Mochi and Hunyuan models support Lora finetuning through diffusers. To generate personalized videos from your own dataset, you'll need to follow three main steps: dataset preparation, finetuning, and inference.

Dataset Preparation

We provide scripts to better help you get started to train on your own characters!
You can run this to organize your dataset to get the videos2caption.json before preprocess. Specify your video folder and corresponding caption folder (caption files should be .txt files and have the same name with its video):

python scripts/dataset_preparation/prepare_json_file.py --video_dir data/input_videos/ --prompt_dir data/captions/ --output_path data/output_folder/videos2caption.json --verbose

Also, we provide script to resize your videos:

python scripts/data_preprocess/resize_videos.py 

Finetuning

After basic dataset preparation and preprocess, you can start to finetune your model using Lora:

bash scripts/finetune/finetune_hunyuan_hf_lora.sh

Inference

For inference with Lora checkpoint, you can run the following scripts with additional parameter --lora_checkpoint_dir:

bash scripts/inference/inference_hunyuan_hf.sh 

We also provide scripts for Mochi in the same directory.

Finetune with Both Image and Video

Our codebase support finetuning with both image and video.

bash scripts/finetune/finetune_hunyuan.sh
bash scripts/finetune/finetune_mochi_lora_mix.sh

For Image-Video Mixture Fine-tuning, make sure to enable the --group_frame option in your script.

📑 Development Plan

• More distillation methods
  • Add Distribution Matching Distillation
• More models support
  • Add CogvideoX model
• Code update
  • fp8 support
  • faster load model and save model support

🤝 Contributing

We welcome all contributions. Please run bash format.sh --all before submitting a pull request.

🔧 Testing

Run pytest to verify the data preprocessing, checkpoint saving, and sequence parallel pipelines. We recommend adding corresponding test cases in the test folder to support your contribution.

Acknowledgement

We learned and reused code from the following projects: PCM, diffusers, OpenSoraPlan, and xDiT.

We thank MBZUAI and Anyscale for their support throughout this project.

Citation

If you use FastVideo for your research, please cite our paper:

@misc{zhang2025fastvideogenerationsliding,
      title={Fast Video Generation with Sliding Tile Attention}, 
      author={Peiyuan Zhang and Yongqi Chen and Runlong Su and Hangliang Ding and Ion Stoica and Zhenghong Liu and Hao Zhang},
      year={2025},
      eprint={2502.04507},
      archivePrefix={arXiv},
      primaryClass={cs.CV},
      url={https://arxiv.org/abs/2502.04507}, 
}
@misc{ding2025efficientvditefficientvideodiffusion,
      title={Efficient-vDiT: Efficient Video Diffusion Transformers With Attention Tile}, 
      author={Hangliang Ding and Dacheng Li and Runlong Su and Peiyuan Zhang and Zhijie Deng and Ion Stoica and Hao Zhang},
      year={2025},
      eprint={2502.06155},
      archivePrefix={arXiv},
      primaryClass={cs.CV},
      url={https://arxiv.org/abs/2502.06155}, 
}