MAI Select Every Nth

Every n-th frame, starting at an offset. That's the whole node. images in, every (default 4), offset (default 0), and the selected frames out. If you're coming from the video world this is a frame decimator; if you're coming from this pack it's the uniform half of the recovery story.

Here's the context that makes it worth a page. The Motion Lab de-rope pipeline fixes MiniMax-H3's fast-motion smearing by slowing a clip down, regenerating it, and then recovering the original frame rate by dropping the held frames. There are two ways that dilation can happen. If you dilated uniformly - an H3 Time Smear with dilation 4 and no hold map - then recovering the original clock is trivial arithmetic: keep every 4th frame, and you're back at the original rate with zero resampling. That's this node.

But the moment you're using an adaptive hold map - the jerk oracle's, or H3 Manual Hold Map's, or the Motion Editor's - holds aren't uniform. Frame 17 might be held once while frame 40 is held four times, and "every 4th frame" lands on the wrong beats. The node description says it in one line: for a smear with a hold map, use H3 Exact Recover instead, because it's exact. Recovery there is frame selection per the hold map, not resampling, and it lands bit-perfect.

So the honest use case for MAI Select Every Nth is narrow but real: you're on the uniform-dilation path, you've decided not to wire an oracle, and you need the recovered clip. It's also handy as a general frame-thinning utility (making a contact sheet, checking timing on a sped-up pass) - every goes up to 256 and offset lets you pick which phase of the cycle survives.

It's part of the MAI video tooling in ComfyUI-MAINodes (matlowai, GPL-3.0) and it's not marked alpha, unlike most of the pack's research surface - the uniform recover is settled math. Install is the pack-wide clone:

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

Restart, and it's under image/minimax/video. Just don't reach for it when a hold map is in play - that's H3 Exact Recover's job, and the difference between them is the difference between a clean de-rope and a stutter.