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MiniMax H3 → LTX-2.5 Fast Refine/Upscale (2-Stage AV Pipeline)

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video_minimax_h3_ltx25_upscale_v3.json

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Published

Sep 5, 2026

Base Model

MiniMax H3

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MiniMax H3 is licensed by MiniMax under the MiniMax H3 Community License Agreement. That agreement’s Applicable Territory excludes the European Union, the United Kingdom, the Republic of Korea and the United States of America. Your use of H3 and of any H3 derivative is subject to that agreement and its Acceptable Use Policy.

MiniMax H3

What's new in v3.0

Adds RIFE frame interpolation before the LTX refine pass — fixes ghosting/warping artifacts on fast-motion or action shots by halving the per-frame motion delta the video VAE sees.

  • Doubles frame count + fps automatically to preserve original duration/audio sync

  • Fully toggleable — off falls back to previous (no interpolation) behavior exactly

  • Requires ComfyUI-Frame-Interpolation (Gourieff/Fannovel16 — install via ComfyUI Manager, search "Frame Interpolation")

Adds render time (roughly doubles Stage 2 compute) — worth toggling off for calm/static shots that don't need it.

Why no v2?
v2 existed internally but wasn't published on its own — it was mostly under-the-hood tuning (fps/wiring fixes) rather than a real user-facing feature. Bundled those fixes into v3 along with RIFE so this jump is worth actually downloading, rather than putting out a version that's basically the same workflow with invisible changes.

What this does

A 2-stage ComfyUI pipeline that pairs MiniMax H3's ref2va generation (strong subject/identity fidelity from reference images, native synced audio) with LTX-2.5's fast distilled sampler as a refine/upscale pass. Built using quantized (int8) models with dynamic VRAM loading — runs comfortably on lower-VRAM cards (3060 / 4070 / 5060 class), not just high-end GPUs.

Stage 1 — MiniMax H3 ref2va: generates your base clip from reference images (face/identity, outfit, environment) with native audio, exactly like MiniMax's own reference workflow.

Stage 2 — LTX-2.5 refine: MiniMax's decoded frames are re-encoded into LTX-2.5's own latent space (the two models don't share a latent space, so this bridges through pixel space) and run through LTX's fast distilled sampler for detail/sharpness — either:

- Native 2x upscale using LTX's own latent upscaler model, or

- Custom target resolution (1920x1080, 1280x720, 1080x1920, or any arbitrary size) via a pixel-space resize before re-encoding

MiniMax's original native audio is passed straight through to the final output — LTX's audio path isn't used at all.

What's tunable

- Sigma schedule + video_cfg on the refine pass — trade off sharpness vs. staying faithful to MiniMax's exact output

- Resolution mode toggle — native 2x model upscale vs. exact custom resolution

- Full prompt/negative-prompt control on the refine pass separately from your MiniMax generation prompt

Not included in this version (coming later)

- RIFE motion pre-interpolation — reduces motion artifacts (ghosting/warping) on fast-action shots by halving the per-frame motion delta the video VAE sees.

- ReActor face-lock — locks final output identity to a reference photo, for cases where the base generation is too low-res for the refine pass to reliably hold facial identity on its own.

Want early access to the upgraded version with RIFE + ReActor before public release? I'm posting it early for supporters here: https://www.patreon.com/c/iiTzMYUNG

Requirements

- MiniMax H3 ref2va models (unet, clip, dual VAE)

- LTX-2.5 models (distilled transformer, video VAE, gemma clip, x2 latent upscale model)

- Standard ComfyUI, no custom node packs required for this version

- Runs on 8-12GB VRAM cards (3060/4070/5060 class) thanks to int8 quantized models + dynamic VRAM loading — no high-end GPU required

Notes

Built and iterated through real trial-and-error on sharpness/identity/resolution tradeoffs — the note nodes inside the workflow explain the reasoning behind each setting if you want to retune it for your own use case.