Select Masks 🎥🅥🅗🅢

Select Masks pulls specific masks out of a stack by index. You type which ones you want - 0, 4, 9, or a range like 0:12 - and it returns exactly those, in the order you asked. It's the mask-track counterpart to Select Latents: same index language, applied to masks instead of latents.

When you're doing per-frame masking across a clip, the mask stack is addressable like a list, and this is the node that lets you address it - filter it down, reorder it, reverse it, grab the last one.

The index syntax

The indexes field is a comma-separated string that understands single indices, negatives, and Python-style ranges with steps. Assuming 16 masks (indices 0–15):

0 → mask [0]
-1 → the last mask, [15]
0, 1, 13 → those three, in order
0:5, 13 → 0,1,2,3,4, then 13 (ranges exclude the end index)
0:-1 → everything but the last
0:5:-1 → [4, 3, 2, 1, 0] (a negative step reverses the range)
0:5:2 → [0, 2, 4] (step of 2)
::-1 → the whole stack, reversed

Because the output follows the order you type, this reorders as easily as it filters. That ::-1 reverse is the quick way to play a mask sequence backwards.

Inputs and outputs

mask (MASK) - the stack to select from.
indexes (STRING, default 0) - the selection expression.
err_if_missing (BOOLEAN, default true) - throw an error if you reference an index that doesn't exist, instead of silently dropping it. Keep it on while building.
err_if_empty (BOOLEAN, default true) - throw if the selection resolves to nothing.

Output is a single MASK stack of exactly your selection.

Installing it

comfy.icu already ships VideoHelperSuite, so the node's there by default.

Locally: ComfyUI Manager → search ComfyUI-VideoHelperSuite → install → restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/Kosinkadink/ComfyUI-VideoHelperSuite

then restart ComfyUI. Kosinkadink's suite, standard for video and per-frame ControlNet setups.

Common issues

Ranges exclude their end index - 0:8 returns eight masks (0 through 7), not nine. That off-by-one is the most common mistake, and it's especially painful when you're trying to line a mask selection up with a matching frame selection. Select the same way on both tracks or they'll drift by one.

Leave err_if_missing on unless you have a specific reason not to. A silently shortened mask stack that no longer matches your images is the kind of bug that produces subtly-wrong results with no error to point at - the loud failure is the merciful one. Turn it off only when you're deliberately over-selecting from a variable-length stack and want the misses ignored.

If the node's absent from the menu, that's VideoHelperSuite failing to import (ffmpeg or a NumPy version clash). The startup log has the cause; reinstall through Manager.