SolitaryThinker 71caa58ba9 [fix] mini-fastvideo serving: address adversarial-review findings (capacity/credit leaks, robustness)
Review confirmed the core bets (concurrent disaggregation is bit-identical, design conformance holds,
Dynamo genuinely optional, engine stays step-scheduled). Fixes for the untested failure paths:

- HIGH: pool capacity (RolePool.in_flight) no longer leaks when a disaggregated request is cancelled
  or errors mid-occupancy — DisaggregatedRunner.close() releases the occupied pool and AsyncEngine._run
  calls it in a finally (a cancel on a capacity-1 denoiser no longer bricks the pool).
- credit flow-control: cross-pool transfer wraps acquire/release in try/finally (no credit leak on a
  failing transfer); slot is re-homed only on a successful fetch.
- AsyncEngine: duplicate in-flight request_id is rejected (was a deadlock); submit() cancels the driver
  task when the consumer abandons the stream (client disconnect → no orphaned compute); bounded
  per-request history (no unbounded _events/_states/_results/_runners growth).
- cancellation is common-path on the OFFLINE path too (cancel check at the top of every runner.tick()).
- HTTP server: read timeout (slowloris guard → 408), body-size cap (→ 413), invalid Content-Length
  (→ 400), explicit StreamReader limit, and aclose() of the SSE generator on client disconnect.
- build_deployment_card no longer aliases one mutable CostModel across replica cards (dataclasses.replace),
  so online calibration of one worker's cost doesn't mutate another's.
- video-job tasks tracked (not fire-and-forget); server.close() cancels/drains them; jobs dict bounded;
  fleet affinity map bounded.

6 regression tests added for these paths. 82 tests pass (pytest + zero-dep runner).
2026-06-18 09:41:12 +00:00
2026-02-23 15:14:42 -08:00
2026-06-09 14:55:55 -07:00
2026-04-02 16:07:24 -07:00
2026-04-02 16:07:24 -07:00
2026-02-10 01:11:17 -08:00
2026-06-18 09:41:11 +00:00
2026-06-18 09:41:11 +00:00
2026-06-18 09:41:11 +00:00
2026-06-18 09:41:11 +00:00
2025-02-20 11:33:58 -08:00
2026-06-18 09:41:11 +00:00
2025-11-27 00:37:03 -08:00
2026-06-18 09:41:11 +00:00

| Documentation | Quick Start | Weekly Dev Meeting | 🟣💬 Slack | 🟣💬 WeChat |

FastVideo is a unified post-training and real-time inference framework for accelerated video generation.

NEWS

More News

Key Features

FastVideo has the following features:

  • End-to-end post-training support for bidirectional and autoregressive models:
    • Support full finetuning and LoRA finetuning for state-of-the-art open video DiTs
    • Data preprocessing pipeline for video, image, and text data
    • Distribution Matching Distillation (DMD2) stepwise distillation.
    • Sparse attention with Video Sparse Attention
    • Sparse distillation to achieve >50x denoising speedup
    • Scalable training with FSDP2, sequence parallelism, and selective activation checkpointing.
    • Causal distillation through Self-Forcing
    • See this page for full list of supported models and recipes.
  • State-of-the-art performance optimizations for inference
    • Sequence Parallelism for distributed inference
    • Multiple state-of-the-art attention backends
    • User-friendly CLI and Python API
    • See this page for full list of supported optimizations.
  • Diverse hardware and OS support
    • Support H100, A100, 4090
    • Support Linux, Windows, MacOS
    • See this page for full list of supported models, hardware assumptions, and optimization compatibility.
  • Realtime video generation & editing
    • Dreamverse: stream and "vibe direct" video in realtime (live demo), deployable on local GPU, a self-hosted B200 server, Docker, or serverless Modal

Getting Started

We recommend using uv to create a clean environment. If you previously used Conda, switching to uv generally gives faster and more stable installs.

# Create and activate a new uv environment
uv venv --python 3.12 --seed
source .venv/bin/activate

# Install FastVideo
uv pip install fastvideo

Please see our docs for more detailed installation instructions.

Sparse Distillation

For our sparse distillation techniques, please see our distillation docs and check out our blog.

See below for recipes and datasets:

Model Sparse Distillation Dataset
FastWan2.1-T2V-1.3B Recipe FastVideo Synthetic Wan2.1 480P
FastWan2.2-TI2V-5B Recipe FastVideo Synthetic Wan2.2 720P

Dreamverse — Realtime Video Generation & Editing

Dreamverse is FastVideo's realtime video generation and editing platform — "vibe directing" a video as it streams. It lives in the monorepo under apps/dreamverse/ and ships its own backend (dreamverse-server) plus a web UI.

Try the live demo, read the blog, or run it yourself. Dreamverse deploys on a local GPU, a self-hosted B200 server over SSH, Docker, or serverless Modal — see the Dreamverse README.

Inference

Generating Your First Video

Here's a minimal example to generate a video using the default settings. Make sure VSA kernels are installed. Create a file called example.py with the following code:

import os
from fastvideo import VideoGenerator

def main():
    os.environ["FASTVIDEO_ATTENTION_BACKEND"] = "VIDEO_SPARSE_ATTN"

    # Create a video generator with a pre-trained model
    generator = VideoGenerator.from_pretrained(
        "FastVideo/FastWan2.1-T2V-1.3B-Diffusers",
        num_gpus=1,  # Adjust based on your hardware
    )

    # Define a prompt for your video
    prompt = "A curious raccoon peers through a vibrant field of yellow sunflowers, its eyes wide with interest."

    # Generate the video
    video = generator.generate_video(
        prompt,
        output_path="my_videos/",  # Controls where videos are saved
        save_video=True
    )

if __name__ == '__main__':
    main()

Run the script with:

python example.py

For a more detailed guide, please see our inference quick start.

Awesome work using FastVideo or our research projects

  • SGLang: SGLang's diffusion inference functionality is based on a fork of FastVideo on Sept. 24, 2025.
  • DanceGRPO: A unified framework to adapt Group Relative Policy Optimization (GRPO) to visual generation paradigms. Code based on FastVideo.
  • SRPO: A method to directly align the full diffusion trajectory with fine-grained human preference. Code based on FastVideo.
  • DCM: Dual-expert consistency model for efficient and high-quality video generation. Code based on FastVideo.
  • HY-WorldPlay: An action-conditioned world model model trained using FastVideo framework.
  • Hunyuan Video 1.5: A leading lightweight video generation model, where they proposed SSTA based on Sliding Tile Attention.
  • Kandinsky-5.0: A family of diffusion models for video & image generation, where their NABLA attention includes a Sliding Tile Attention branch.
  • LongCat Video: A foundational video generation model with 13.6B parameters with block-sparse attention similar to Video Sparse Attention.

🤝 Contributing

We welcome all contributions. Please check out our guide here. See details in development roadmap.

Acknowledgement

We learned the design and reused code from the following projects: Wan-Video, ThunderKittens, DMD2, diffusers, xDiT, vLLM, SGLang. We thank MBZUAI, Anyscale, and GMI Cloud for their support throughout this project.

Citation

If you find FastVideo useful, please consider citing our research work:

@article{zhang2025vsa,
  title={Vsa: Faster video diffusion with trainable sparse attention},
  author={Zhang, Peiyuan and Chen, Yongqi and Huang, Haofeng and Lin, Will and Liu, Zhengzhong and Stoica, Ion and Xing, Eric and Zhang, Hao},
  journal={arXiv preprint arXiv:2505.13389},
  year={2025}
}

@article{zhang2025fast,
  title={Fast video generation with sliding tile attention},
  author={Zhang, Peiyuan and Chen, Yongqi and Su, Runlong and Ding, Hangliang and Stoica, Ion and Liu, Zhengzhong and Zhang, Hao},
  journal={arXiv preprint arXiv:2502.04507},
  year={2025}
}
S
Description
No description provided
Readme
438 MiB
Languages
Python 89.6%
TypeScript 5.6%
Cuda 2%
C++ 1.1%
Shell 0.7%
Other 0.9%