MiniMax H3 Source Timeline Scene Preview

Once your source media lives behind a Source Timeline descriptor, it's easy to lose track of which exact window each Plan scene maps onto - especially with sequential timeline mode advancing through a long file. This node decodes and shows you precisely the slice one scene will pull, video and audio together, so you can verify the motion and the sound are the ones you intended before you queue an expensive render. It's an inspection node, not a generation node, and it's the cheapest insurance the pack offers against "scene 5 used the wrong ten seconds."

What it does

Connect the source_timeline descriptor and pick a scene (1–128, the arrows act as a counter). Then:

• timeline_mode - use the same window rule as Tagged Motion Ref: sequential advances the 24 fps source along the Plan timeline, restart_each_scene starts at frame 0 for every scene. Match this to whatever your motion-reference path uses or the preview lies.
• reference_short_edge - preview decode size (384, 512, 768, or source). Keep it small; it's a preview.
• include_audio - decode the identical audio window when available.

The optional plan input is required to resolve scene windows - without a Plan, both media outputs stay blocked. Outputs are scene_video (the decoded 24 fps picture window), scene_audio (the matching sound, or blocked when disabled/unavailable), and status (scene, rule, frame count, dimensions).

The mirror-image sibling of this node is Lazy Motion Scene Preview, which inspects a motion-reference window; this one inspects the source timeline. Use each where it belongs.

Install and gotchas

cd ComfyUI/custom_nodes
git clone https://github.com/ethanfel/ComfyUI-MiniMaxH3-Contex-Loop.git

Restart, or install via ComfyUI Manager under "MiniMax H3 Contex Loop". No pip dependencies; a current ComfyUI with native Add Guide (PR #15439) is expected, and ffmpeg on PATH is preferred. Models aren't bundled - check the MiniMax H3 Community License territory restriction.

The one thing that bites people: a missing plan means silent blocked outputs, which reads as "broken node" until you realize the design refuses to guess scene windows. And keep timeline_mode consistent with your actual motion path - previewing in restart_each_scene while generating in sequential will convince you the timing is fine right up until it isn't.