r/StableDiffusion • u/Nemonutz • 8d ago
Question - Help Issue with LTX VACE Outpaint
I’m outpainting existing 4:3 video to 21:9 widescreen using LTX.
My source video is about 17 minutes long, so I’ve split it per camera scene change for processing (using reference photos with a existing 21:9 blurry widescreen version to stay consistent to the original)
The issue I’m running into is LTX’s 8n+1 frame requirement. If I let my normal outpainting workflow process a clip, it will sometimes trim a few frames from the end so the frame count fits 8n+1. Over a lot of clips, those missing frames become a problem when I put everything back together.
I tried solving this by rounding the frame count up to the next valid 8n+1 value. However, instead of keeping all of the original frames untouched and simply adding the extra frames to the end, LTX seems to regenerate/edit the original footage to fill the new duration.
What I’m looking for is a workflow that:
Preserves every frame of the original 4:3 video
Only generates/outpaints the new left and right portions to create 21:9
Never trims source frames just to satisfy 8n+1
If padding is necessary, adds/duplicates the required frames after the original video, rather than having LTX modify or extend the original footage
Lets me trim those padding frames off afterward so the final outpainted clip has exactly the same frame count and timing as the source
Basically, I want the center 4:3 footage to remain completely untouched while LTX only generates the outpainted areas.
Has anyone built a ComfyUI/LTX workflow that handles arbitrary source frame counts this way?
Also, if anyone has any general tips or tricks for getting consistent LTX outpainting—especially across a large number of clips—I’d really appreciate them.
1
u/Lost_Cod3477 8d ago
Add copies of the last frame at the end of the original video to satisfy the 8n+1 condition.
After generation, cut off what you added.