H3 Motion Editor (timeline, masks, automation) [alpha]

Alpha, and the most ambitious node in the pack: a DAW-style editor that lives right on the ComfyUI canvas. Where the classic pipeline trusts the oracle to decide where motion is too fast, H3 Motion Editor lets you decide - by dragging time blocks onto a timeline and painting the problem areas frame by frame. It compiles to the same hold_map and MASK wires everything downstream already eats, so it's a drop-in for the pipeline, not a fork of it.

The workflow

Queue once to load the filmstrip, then work on the node itself. With no blocks laid out yet and hold_until_edited on (default), the graph stops here after writing the filmstrip - nothing downstream runs - so you can't accidentally trigger the expensive regen before you've touched anything. Layout your blocks, then:

• Drag bracket blocks on the timeline - multiple blocks, snapped to the model's token grid, with the jerk profile drawn underneath so you see what the oracle sees.
• Click a block and paint the problem areas with brush and eraser, frame by frame, onion skin included.
• Set per-block dials - hold, feather size, feather profile and direction, edge grow, temporal fade.
• Toggle A on hold, feather, or strength to draw an automation envelope with draggable breakpoints, exactly like an automation lane in a DAW.

A block with no strokes regenerates its whole time span; strokes narrow it to the painted region. Queue again and only the regeneration side re-runs - the baseline stays cached, so edits are cheap to iterate.

Inputs that matter

• images - the baseline frames on the world clock (required).
• editor_state - the serialized state the GUI widget maintains (required, but you don't touch it by hand unless you're an agent).
• samples - the baseline latent, which drives the jerk profile strip.
• oracle_hold_map - wire the oracle to gate it; blocks with hold=0 use oracle holds.
• outside_blocks - what the composite shows on frames no block covers: baseline or regenerated.
• paint_res (512) - the mask compile width; the composite rescales to full res.

Outputs are the drop-ins: hold_map → H3 Time Smear, mask → H3 Motion Composite (enable mask_is_soft there - the mask comes out already feathered and envelope-scaled), envelopes for inspection, and a report that prices the pass before you run it.

The agent angle

The editor state is plain JSON with a documented contract in the node's docstring ({"v": 1, "blocks": [...]}). Agents can author that JSON directly and skip the GUI entirely - the compile step is the same either way. If that matters to you, it's one of the nicer things about this node: the GUI is a convenience surface, not the interface.

Install

cd ComfyUI/custom_nodes
git clone https://github.com/matlowai/ComfyUI-MAINodes

or ComfyUI Manager → ComfyUI-MAINodes, restart. Category latent/minimax/motion. It's an output-capable node (it can stop the graph after the filmstrip), and it's alpha - the interactive widget is young, so don't be shocked if the GUI evolves.

Common gotchas

Remember the grid: blocks snap to token boundaries, so a block you meant to start at frame 40 can land on 43. And invert_mask flips the final mask if you'd rather paint keep-baseline regions instead of regen regions. If your re-queues suddenly re-run the baseline, you edited something upstream of the cache - the "only regen re-runs" promise holds as long as the baseline branch is untouched.