AD_frame_replace

Anyone who's run a long AnimateDiff or LTX batch knows the pain: 90 frames come out fine except frame 34, which has a mangled hand or a flickering artifact, and re-rendering the whole clip to fix one frame is a waste of GPU time. AD_frame_replace is the surgical-fix node for exactly that - it either lets you pull a specific frame range out of a batch to inspect or export, or slot a replacement frame (and its mask) into that range and get the full batch back, patched.

How it works

It's index-based, not content-aware - you tell it where to look (start_index, num_frames) and what mode to run in (type), and it either hands you just that slice or stitches your replace_img/replace_mask into the batch at that position and returns everything.

The inputs and outputs that matter

• start_index (default 0, min -1) - where the frame range begins. The -1 floor suggests it supports counting from the end of the batch, worth testing if you need to target the tail of a sequence rather than counting forward from zero.
• num_frames (default 1) - how many frames the range covers, starting at start_index.
• type - the mode switch: choose frame output just extracts and returns that slice, while replace frame and output all swaps that slice for your replacement content and returns the entire original batch with the patch applied.
• images / masks (optional) - the source batch you're operating on.
• replace_img / replace_mask (optional) - the patch content, only relevant in replace mode.

Outputs are IMAGE and MASK - either the extracted slice or the full patched batch, depending on which mode you ran.

How to install it

Via ComfyUI Manager: search "ComfyUI-Apt_Preset", install, restart. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/cardenluo/ComfyUI-Apt_Preset.git

Then, per the pack's README, run install.bat on Windows (double-click it) or pip install -r requirements.txt from inside the folder on Linux/Mac if there's no .bat support on your system. Restart ComfyUI. This particular node does no model loading and needs no extra downloads - it's pure batch-index plumbing.

Common issues & troubleshooting

Nothing changes in replace mode. Double-check you're actually on replace frame and output all - the default type is choose frame output, which silently just extracts a slice and discards your replace_img/replace_mask inputs entirely. If you wired up replacement content and nothing's happening downstream, you're probably still in extract mode.

Off-by-one frame mismatch. start_index plus num_frames defines the range being touched - if your patch is landing one frame early or late, it's worth explicitly counting frame position in your batch rather than eyeballing it in a preview, especially since batch previews and node-graph frame counts don't always agree at a glance.

Replacement content doesn't match the batch's frame count. In replace mode you're inserting a fixed-size chunk (num_frames long) into a fixed position - if replace_img/replace_mask supply a different number of frames than num_frames expects, that's a mismatch worth fixing at the source rather than assuming the node will silently pad or truncate for you.

Trying to use this for anything content-aware. This node doesn't detect bad frames for you - it's a manual scalpel, not an auto-fix. You still need to know which frame is broken (from a preview or a failed run) before you can tell this node where to cut.