Wan Replace First Frame (QQ)

WanReplaceFirstFrame does literally one thing: it swaps the first frame of a video for an image you provide. Two inputs - image (the single frame to use) and video (whose first frame gets replaced) - and one output: video, identical to the input except frame zero. It's the most boring node in the pack, and that's its entire appeal.

Why does a one-line operation deserve a node? Because in Wan I2V workflows the first frame is a load-bearing fact. The model anchors everything to it, and the community's chaining trick - take the last frame of clip 1, feed it as the first frame of clip 2 - depends on being able to swap that anchor precisely. This node is how you fix a bad first frame without re-rendering an entire 81-frame pass, or how you retarget a clip that was generated from one reference onto another start image for a quick consistency test. Combined with the wrapper's re-encode path, you get a lightweight "regenerate with a different start" loop.

The practical pattern: generate a clip, decode it, inspect the first frame, and if it's wrong (face glitch, framing off), swap in the still you actually wanted - then continue downstream as if it had been correct. It's also the cheap companion to VideoLoopMove for looping: re-anchor the loop's start to a frame that makes the seam invisible.

The gotchas that matter

• The tooltip says "Single image to replace the first frame" - batch inputs aren't the point here. Feed it one image.
• It's a pixel-level swap on decoded frames, so it sits after VAE decode. It won't re-condition the generation - the rest of the video still came from the old first frame, so if the new image contradicts what follows, the inconsistency will show. Use it for polish and anchoring, not for retroactively changing the generation's premise.
• Resolution mismatch between the image and the video frames can cause a size mismatch downstream - resize the image to match the clip first.

Installing it

Part of siraxe/ComfyUI-WanVideoWrapper_QQ. ComfyUI Manager → search WanVideoWrapper_QQ (or SA-Nodes-QQ), or:

cd ComfyUI/custom_nodes
git clone https://github.com/siraxe/ComfyUI-WanVideoWrapper_QQ.git

Restart ComfyUI. No extra dependencies.

One pack-level note that applies to every node in this collection: the repo was renamed to ComfyUI-SA-Nodes-QQ in v1.3.4, and older workflow JSONs referencing the old wanwrapper_qq pack can trigger an unintended install - delete any stale wanwrapper_qq folder in custom_nodes if you see it.