How to change one object in a video without the edit changing everything else
Tell Vizard Agent which single element changes and list what must survive untouched: the timing, the camera, the effects, the ending. An edit given a loose brief re-renders the whole shot, so the check that matters is a frame comparison against the source, not whether the new object looks good.
What do you type into Vizard Agent?
Write the exclusions as a list. In a shot where an object cracks, transforms and becomes something else, "keep everything else the same" isn't specific enough for Vizard Agent to test against, but "preserve the crack timing, the neon, the road transformation and the final logo" is. Say what the object becomes at each moment, too.
Prompt
What does Vizard Agent actually do?
It checks the result against the source rather than judging the output on its own merits, because that's the only way drift shows. When a generative pass won't hold still, it falls back to a local composite that changes only the pixels you asked about. In the session behind this article it:
- Examined the fall, the crack and the transformation of a stylised vertical clip frame by frame, recording the exact positions of both pieces before and after the break.
- Kept an identical copy of the original as a clean reference, then applied a targeted edit to one piece only, keeping the vertical format.
- Compared source and result in one control view and found the new object looked right, but the opening second was gone and the crop had shifted.
- Located the exact cut point and spliced the original opening back, measuring frame rates and timings to build a clean join.
- Extracted a clean texture of the original ball, measured the piece's path frame by frame, composited the replacement along it and corrected the crop and the mask centre.
- Delivered both versions: the local composite and the untouched original.
When does this not work well?
Some objects can't be changed in isolation. If the thing you're replacing lights the scene, is reflected in other surfaces, or is what the effects react to, changing it means changing everything it touches, and that is a regeneration, not an edit. Heavy motion blur, objects that deform and very short appearances are hard too.
Common questions
Why does an edit change things I did not mention? Because it re-renders the shot. Vizard Agent limits the change and verifies the rest.
What if the object splits into two? Say what each piece becomes and when. Vizard Agent tracks them separately.
How do I check it myself? Look at the first and last second of what Vizard Agent returns. That is where drift hides.