LTX-2 Extension Module (simple) ??

Here's the thing about the full LTX2 Extension Module: it's powerful, and it has seventeen knobs. This one is the version where the author took all seventeen knobs, hid most of them, and made the sensible decisions for you. If you're extending LTX-2 video in segments - and that's the whole point of this pack - start here, not with the big one. You can graduate to the flagship later, but the simple version is the one that gets your first long clip made.

How it works

ExtensionModule_simple is literally the same code as IAMCCS_LTX2_ExtensionModule - it subclasses it and calls the identical processing function - with the quality-tuning surface stripped out and one hardcoded behavior: it always enforces the LTX-2 8n+1 frame rule on the start_images it extracts (ltx2_round_down), because those frames go straight into a VAE encode for the next pass and an illegal count is an instant failure. The full module lets you toggle that off for compatibility with older workflows; the simple one doesn't let you shoot yourself.

The core job is stitching. Give it source_images (the footage you already have) and new_images (the fresh chunk you just generated), and it:

1. Picks overlap_frames from one side (overlap_side: from the source tail, or from the new chunk's head).
2. Blends that overlap region - cut for a hard join, or one of the crossfades (linear_blend default, ease_in_out, filmic_crossfade, perceptual_crossfade) for a soft one.
3. Outputs start_images - the overlap frames for the next pass's first-frame conditioning - and extended_images, your growing video.

The inputs and outputs that matter

The full module buries these under color-match and seam-search settings; here they're the whole UI:

• source_images - the footage so far.
• overlap_frames - how many frames to overlap between passes (default 10).
• overlap_side - take the overlap from the source tail or the new chunk's head (default source).
• overlap_mode - blend method, default linear_blend.
• enable_math + math_operation - an odd but handy feature: it adjusts the overlap count arithmetically. a-b (default) subtracts math_value_b from the overlap, which is the classic trick for LTX where you want the passed-along start frames to be 8n+1 while the blend window stays slightly different. Default math_value_b is 1.
• new_images (optional) - the current generation's output.

Outputs: source_images (pass-through), start_images, extended_images, then overlap_frames, calculated_frames, and extension_frames as INTs (handy for wiring into your sampler's length), plus report.

Installing it

In IAMCCS-nodes. Manager → "IAMCCS" → install, or:

cd ComfyUI/custom_nodes
git clone https://github.com/IAMCCS/IAMCCS-nodes.git

Restart ComfyUI, look under IAMCCS/LTX-2. No models, no dependencies.

Common issues

The one real footgun is the enable_math/math_operation pair being on by default with a-b - it quietly shrinks your overlap by one frame, which is deliberate (it's how the pack keeps start frames 8n+1 while blending 10 frames) but looks like a bug if you don't know it. If you want your overlap to be exactly what you set, switch math_operation to none. Otherwise, the usual extension pitfalls apply: overlap larger than your shortest chunk breaks the math, and cut mode will show a seam if your two chunks drift - switch to a crossfade before you blame the model.