> ## Documentation Index
> Fetch the complete documentation index at: https://docs.comfy.org/llms.txt
> Use this file to discover all available pages before exploring further.
# FastVideo FastH3: ComfyUI Workflow Examples
> Generate MiniMax H3 video with synchronized audio in 8 sampling steps in ComfyUI using the FastVideo FastH3 distilled checkpoint: text-to-video and first/last-frame workflows.
[FastVideo FastH3](https://huggingface.co/FastVideo/FastVideo-FastH3-8-Step-V2) is a DMD2-distilled MiniMax H3 checkpoint from the FastVideo team that generates video with synchronized native audio in **8 sampling steps** instead of the base model's full schedule. It reuses the H3 text encoder, video VAE, and audio VAE, so output matches the base model's setup while sampling finishes in a fraction of the steps.
The FastH3 preview work was developed in collaboration with Nuva Lab and the NVIDIA FastGen team; read the [FastH3 announcement](https://haoailab.com/blogs/fasth3-preview/) for distillation details. ComfyUI ships with the 8-step V2 checkpoint, repacked by Comfy-Org in the [FastVideo-FastH3-Comfy](https://huggingface.co/FastVideo/FastVideo-FastH3-Comfy) repository.
FastH3 trades some motion and audio fidelity for speed. Use it for drafts, iteration, and fast turnaround; use the base MiniMax H3 workflows when maximum quality matters.
The distilled checkpoint supports text-to-video and first/last-frame image-to-video only. Ref2VA (multi-reference conditioning) was not distilled; use the base [MiniMax H3 workflows](/tutorials/video/minimax/minimax-h3-native) for reference-based generation.
## Requirements
* ComfyUI 0.36.0 or later
* The MiniMax H3 text encoder and VAEs (shared with the base model, listed below)
## FastH3 Text to Video
Generate synchronized video and audio from a text prompt in 8 steps.
Download JSON or search "FastVideo FastH3: Text to Video" in Template Library
### Prompting tips
1. **Describe the whole scene**: State the overall scene first (location, character, what is happening), then break it into timed shots
2. **Shots, camera, and audio**: Describe the shots, camera moves, and the accompanying audio (dialogue, SFX, music) in one prompt block
3. **Resolution**: H3's native canvas is a 768px short edge, capped at 768x1344, and resolutions are rounded to a multiple of 32
4. **Duration**: The duration input snaps to the model's 17-frame-per-block (17k+5) grid at 24fps
5. **Steps are fixed at 8**: The distilled checkpoint is trained for exactly 8 steps; changing the step count in the scheduler degrades quality
For prompt writing resources, see the [prompt guide](/tutorials/video/minimax/minimax-h3-prompt-guide).
## FastH3 Image to Video
Animate a still image with synchronized audio, with optional first/last-frame control.
Download JSON or search "FastVideo FastH3: Image to Video" in Template Library
**Input material**
Upload this file to the matching `LoadImage` node, or use your own image:
Example first frame for the Image to Video workflow
### First/last-frame mode
Connect images to `first_frame` and/or `last_frame` on the `MiniMaxH3ImageToVideo` node to generate the motion between two keyframes. Leave both disconnected for text-to-video.
### Prompting tips
1. **Describe the motion and audio**: With an image providing the look, the prompt should focus on motion, camera, and the accompanying audio
2. **Duration**: The duration input snaps to the model's 17-frame-per-block (17k+5) grid at 24fps
3. **Steps are fixed at 8**: Keep the scheduler at 8 steps; the checkpoint is distilled for that schedule
## Model downloads
The diffusion model comes from the FastVideo repository; the text encoder and VAEs are shared with the base MiniMax H3 model.
Place in ComfyUI/models/diffusion\_models/
Place in ComfyUI/models/text\_encoders/
Place in ComfyUI/models/vae/
Place in ComfyUI/models/vae/
### Model storage
```
ComfyUI/
├── 📂 models/
│ ├── 📂 diffusion_models/
│ │ └── fastvideo_fasth3_8step_v2_pruned_int8_convrot.safetensors
│ ├── 📂 text_encoders/
│ │ └── qwen3vl_32b_minimax_h3_nvfp4_awq.safetensors
│ └── 📂 vae/
│ ├── minimax_h3_video_vae_fp16.safetensors
│ └── minimax_h3_audio_vae_fp32.safetensors
```
## Workflow structure notes
Both FastH3 workflows share these nodes with the base H3 setup, with distillation-specific settings:
* **BlockSparseAttention**: Runs Video Sparse Attention (VSA) with `keep_percent` 10 starting at 20% of the schedule, reducing attention cost while preserving quality
* **MiniMaxH3SigmaShift**: Applies the H3 sigma shift (10 for video, 3 for audio) that matches the distilled schedule
* **ComfyMathExpression**: Converts the duration input into a valid frame `length` on the 17k+5 grid at 24fps
* **Sampler**: `res_multistep` sampler with the `simple` scheduler at 8 steps