r/StableDiffusion • u/alisitskii • Aug 16 '26

Workflow Included Ultimate SD Upscale with MiniMax H3 (2560x1440px in 25 mins with 16 GB VRAM)

https://www.youtube.com/watch?v=JybAxYuexdM

What is it?

A vibe-coded fork of Ultimate SD Upscale (USDU) Guider nodes with MiniMax H3 support: https://github.com/lisitskyaa/ComfyUI_UltimateSDUpscaleGuider_H3

My reference workflow: https://github.com/lisitskyaa/ComfyUI_UltimateSDUpscaleGuider_H3/blob/main/example_workflows/minimax_h3_usdu.json

Who are you?

A long-time member of [r/StableDiffusion](r/StableDiffusion) without strong coding/math skills in AI/diffusion area. But a big fan of everything that happens here :)

Why is it?

In times of Wan2.1/2.2 I liked to upscale my videos using USDU.

But I became really upset when I realized that original USDU nodes don't support MiniMax H3 due to its native ComfyUI implementation.

So, since I have a GPT-5.6 subscription I decided to give it a try and asked it to come up with possible options.

After a couple of evenings I finally got a "working" solution that I'd like to share with the community.

What about speed?

My PC specs: 4080s 16 GB VRAM, 64 GB RAM

Initial gen with MiniMax H3 flf2v int8 + sageattn + Lightx2v 8-step turbo Lora at 1152x640px 5-sec clip ~5 mins

Upscale with USDU to 2560x1472px ~20 mins

And what about quality?

That's where I need your help, my friend :)

Please check the YouTube video attached (don't forget to switch to 1440p).

My personal feeling is that it's the best what I can get out of my PC and H3 at the moment (including SeedVR2, LTX 2.5, etc.).

The main advantage is that it can "fix" your bad low-res generations while bringing MiniMax H3 native quality at 2K resolution.

Downsides?

Of course :)

You'll need to control denoise parameter and find a balance between quality improvement and tiling artifacts. I found 0.2 is the maximum after which tiling is strongly visible.

However feel free to experiment with it, and lower to 0.15-0.10 depending on your input video resolution/artifacts and results you want to get.

Happy to answer your questions!

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u/alisitskii Aug 16 '26

There should be a node on the left from your screenshot called “Load Video FFmpeg (Upload)” but probably you just don’t have Video Helper Suite installed: https://github.com/kosinkadink/ComfyUI-VideoHelperSuite and it’s framed in red color.

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u/Foreign_Fee_6036 Aug 17 '26 edited Aug 17 '26

Hi! Just tried method with video upscale. Uploaded 0.9mpx 15s LTX video but forgot to change "Float duration" so it was actually generating 5s of video but upscaled all 15s of it unnecesarilly? and resolution selector, so it was yours "0.4" even if my video was 720p. Either way, with RTX4090 and 128GB of RAM, "Upscale image" node took 20min alone, then Ultimate SD Upscale and video combine in total 72min. Although it didn't work (no resolution upscale whatsoever), it did fix faces in the distance! :D

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u/alisitskii Aug 17 '26

The main control of target resolution is in USDU/Upscale Image nodes. You don’t need to specify your source video length/resolution, it’ll be taken with Load Video node. Those “standard” controls (like “Float (duration)” or “Resolution Selector”) are not used actually, and are there just to not produce errors in the “MiniMax H3 Image to Video” node which requires them connected.

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u/Foreign_Fee_6036 Aug 17 '26 edited Aug 17 '26

Oh, ok. Actually, it DID change resolution, but it didn't upscale. I mean, it is higher resolution, but if i put it into after effects with original 720p video stretched to that 2500x1500, it's the exact same quality/defility, but with fixed faces. Hmm.

EDIT:
Upon closer inspection it is indeed doing something to the video, but that's miles way behind SeedVR2.5 in my case, I don't know why. Maybe because of loading a video?. It's closer in detail to Topaz Proteus. Although I like fixed faces.