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Three ComfyUI workflows for MiniMax H3 that turn a source video of any length into a new video, clip by clip,

on a single 16 GB GPU. They need the custom node pack ComfyUI-H3-LongTake (MIT, no extra Python dependencies):

👉 https://github.com/mark9009/ComfyUI-H3-LongTake — install, models list, tested use cases with the exact prompts, prompting guide.

What the node does

- Slices the source video into 124-frame clips (5.2 s) that overlap by 5 frames, decodes only each slice with ffmpeg, and renders them one after the other.

- Every clip gets the previous clip's latent tail as an H3 keyframe, so the seam is continuous (measured 0.96 continuity) and the video follows the source with no drift over minutes of material.

- Resumable projects: stop ComfyUI, queue again, it continues from the first missing clip. Redo a single clip redo_one) or everything from clip N redo_from) with a new seed while the seams stay.

- seam_match = color removes the colour/exposure jump between clips (ΔE 5.8 → 0.9).

- The Stitch node concatenates the clips without re-encoding, puts the original audio back and embeds the workflow in the mp4 (drag the result into ComfyUI to reopen the project).

The three workflows

1. H3_LongTake_character_swap — a picture's character performs the whole video source_role = reference, Ref2VA). Identity from <Picture 1>, motion, timing, camera and room from the video. Works with photoreal and anime references; the video's room is kept even when the picture has its own background (say so in the prompt).

2. H3_LongTake_example — the same, with the structured H3 prompt (subject definitions / retention analysis) for motion + identity transfer.

3. H3_LongTake_style — style transfer and retexture with the StyleTransfer LoRA by NRDX (https://civarchive.com/models/2932297): the video becomes a guide latent source_role = guide), motion and framing are reproduced frame by frame (adherence 0.93), the style comes from text (Van Gogh, Ghibli, Simpsons, GTA…) or from a style swatch as <Picture 1>. retexture: changes the material/colour of one garment and nothing else.

Models (all from the official Comfy-Org MiniMax-H3 release unless noted)

- minimax_h3_ref2va_pruned_fp8_scaled.safetensors (diffusion_models)

- a MiniMax H3 Qwen3-VL-32B text encoder build (int8 or nvfp4; ~25 GB, kept in system RAM)

- minimax_h3_video_vae_fp16.safetensors, minimax_h3_audio_vae_fp32.safetensors (vae)

- minimax_h3_ref2v_turbo_4step_v0.1_comfyui_bf16.safetensors (loras) — 4 steps

- optional: minimax_h3_style_transfer_v1.0_r64.safetensors by NRDX (loras) — style workflow only

Quick start

1. Load a workflow, put your video in ComfyUI/input/ and pick it in source_file; connect your picture to ref_image_1.

2. dry_run = true → the node prints the slicing plan.

3. dry_run = false, max_clips = 2 → check identity/style and the seam in the preview.

4. max_clips = 0, mode = continue → the whole video. Unmute the Stitch node (Ctrl+M) when all clips are done.

Timing on a 16 GB GPU at 544×960: about 4:40 per 5-second clip with 4 Turbo steps (~1 minute of video per hour).

Prompting rules that came out of the tests

- Named styles work from text alone: 3–5 visual attributes + "Keep the original room, background, framing and motion exactly as in the video; do not add any new scenery." Never a style name and <Picture 1> in the same sentence.

- Style pictures without faces or scenery (crop a swatch): a face transfers the identity, a skyline replaces the room.

- Character swap: describe the character in words as well as <Picture 1>, and forbid the picture's background explicitly. A picture framed like the video keeps the motion in sync.

- retexture: names the exact garment ("the dress", not "the outfit").

Examples in the gallery (source | result): character swap from a photoreal picture, Van Gogh, Studio Ghibli, GTA from a swatch, The Simpsons on a 16:9 press conference, pop-art from a halftone swatch, gold-armour retexture. Source clips are free Pexels videos and a film excerpt; the character reference is an AI-generated picture.

Credits: motion-context idea by NikoDemon80 and the Banodoco MiniMax H3 thread; StyleTransfer LoRA by NRDX; MiniMax H3 core nodes by Comfy-Org. Node pack and workflows: mark9009.