SCAIL Full-Length / Preview Planner

SCAIL-2's native window is 81 frames. Everything longer gets chopped into chunks, and on a mid-range card each chunk costs minutes to tens of minutes - so before you queue a three-minute clip, you want to know how many chunks that is and how long it'll run. SCAILFullLengthPlanner is the piece of paper you'd otherwise scribble on: a pure utility node that takes your frame batch and answers the question with actual numbers.

What it does

No VLM, no model, no VRAM. You feed it the same video_frames batch your video loader outputs, pick a mode, and it computes the internal frame plan: SCAIL wants frame counts in the 4n+1 shape (so a 272-frame video becomes 273 internally), it applies the 81-frame chunk with your configured overlap, and it spits out the chunk list, expected output length, and a rough time estimate. It also gives you a frame_load_cap number you can wire straight into a Video Helper Suite loader to actually restrict the preview.

The mode that matters

• mode - preview_81 (default) caps the plan at the first 81 frames, which is the standard sanity check before committing to a full render. full_length plans the whole clip.
• chunk_length (81), overlap (5), fps (30) - the geometry of the chunking.
• minutes_per_81_frame_chunk (24.5) - this is a calibration knob, and it's the one beginners get fooled by. 24.5 minutes per 81-frame chunk is what the author's machine roughly does. On your hardware it's faster or slower, so tune it against one real render or the estimate is fiction.

Outputs: report (STRING - the whole readable plan), frame_load_cap (INT - 81 in preview mode, 0 for full-length, meaning "unlimited"), input_frames and expected_output_frames (INTs), and estimated_minutes (FLOAT).

The gotcha that makes the preview mode fiddly

The README is upfront about the catch: the current workflow uses ComfyUI's core LoadVideo, which has no frame_load_cap. So in preview mode this node can tell you the 81-frame plan, but it can't enforce it on the loader. To get an actual 81-frame test you either pre-trim the clip or switch the loader to Video Helper Suite's VHS_LoadVideo / VHS_LoadVideoPath and wire frame_load_cap from this node's output - where 0 means unlimited (full render). That's the classic preview/full-length control, and it's the difference between this node being a calculator and being a real gatekeeper in the graph.

Install

Same pack as the rest of the SCAIL Auto Prompt Builder family - ComfyUI Manager search "SCAIL Auto Prompt Builder," or git clone https://github.com/klimentiy23/scail-auto-prompt-builder into ComfyUI/custom_nodes and restart. Unlike its siblings, this one has zero model dependencies: no LLM folder, no transformers, nothing to download. It's the cheapest node in the pack to adopt, and honestly the one you might keep even if you never use the VLM prompt writers - knowing a 1,400-frame clip means roughly seventeen chunks before you queue it is exactly the information that stops a "why is this still running" rage quit at 3 a.m.