MiniMax H3 Project Setup (Plan v2)

MiniMax H3 doesn't do "as long as it needs" videos. It does 4 to 15 seconds, on a fixed frame grid of 5 + 17k frames at a locked 24 FPS - 107 frames on the short end, 362 frames (15.083 seconds) on the long one. That grid is the single most annoying thing to get wrong when you're hand-writing H3 prompts, and it's the whole reason Project Setup is the first node in this pack's Plan v2 chain.

Everything downstream in ComfyUI-MiniMax-H3-Guide hangs off the value this node creates. You pick the output length once here, and every reference, shot, and the final compiled prompt inherit that length. If your Project duration and your source media disagree, the compiler will complain loudly instead of silently producing a clip that cuts off or pads with junk.

What it owns

Project Setup is a typed Plan v2 start. It creates the MINIMAX_H3_PLAN_V2 value that every other node in the pack threads through, and it sets the global intent your shots will build on.

The inputs that actually matter for a beginner:

• frame_count - the big one. It steps through the native 17k+5 grid from 107 to 362 (default 158, which is 6.58 seconds at 24 FPS). The tooltip calls it "authoritative," and it is: this is the number the whole timeline is validated against.
• initial_prompt - the overall target. For a simple one-shot video, this can be nearly your whole prompt. Shot nodes later hold the chronological detail.
• visual_style - a global treatment like "cinematic, live-action" that every shot inherits.
• overall_soundscape - global ambience. Leave it blank when a complete copied audio signal will be the entire final track (that's a real gotcha - see the pack's Foley docs).
• non_diegetic_music - the audience-only score. Set it to N/A when you want none, which is most of the time.
• fps - locked to 24. There's nothing to configure; it's a reminder that H3's timeline is fixed.

The h3_length output gives you the exact native frame count for other nodes, and project_preview shows what you selected.

Install

The pack is dependency-free - no extra Python packages, no pip step. From your ComfyUI root:

cd ComfyUI/custom_nodes
git clone https://github.com/ethanfel/ComfyUI-MiniMax-H3-Guide

Restart ComfyUI and look under MiniMax H3 → Plan v2. You can also install via ComfyUI Manager by searching "MiniMax H3 Guide". One requirement to know before you start: you need a ComfyUI build with native MiniMax H3 support - the MiniMax H3 Image to Video / Reference to Video nodes and the MiniMax tokenizer. Update ComfyUI if those are missing.

Gotchas

• The frame count is not arbitrary. Project Setup rejects non-native values. If your reference video is 5.7 seconds, don't fight it - the pack rounds duration up to the nearest grid value (there's a native_frame_count helper that does exactly this).
• Keep the pack author's framing in mind: ethanfel also builds ComfyUI-LoRA-Optimizer, and this pack has the same "deterministic, compiler-owned structure" DNA - the node is meant to remove ambiguity, not add freedom.
• One thing worth knowing about H3 itself before you spend a weekend on this: the open weights are geofenced. The MiniMax H3 Community License excludes the US, EU, UK and South Korea from its applicable territory. The node pack runs fine anywhere - it's just prompt plumbing - but if you're in one of those regions, check whether you're licensed to run the H3 weights at all before building your whole pipeline.