I need to overlap one video on top of another one using AlphaOver. I have done this before. The tricky part this time around is that the one that I’m AlphaOvering, is shorter than it’s background counterpart (the other video).
My question is: How do I position the small one in a precise place in respect of the large one (the background)? Let’s say, to make it start at frame number 400 (which is half way the length of the large one).
I hope I was clear enough.
Thanks in advance guys,
JDL
Wouldn’t this be pretty easy in the video sequence editor? You could very easily slide the footage around in time to where ever you’d like.
Hype does have a point in suggesting the sequencer; if all that’s you wanna do then it’s more transparent and manageable in the VSE.
If not, set the offset in the image input node to whatever suits your purposes.
You were right guys 
I ended up doing it in VSE indeed.
Thank you guys.
JDL
I agree that this is a problem that should be addressed using the sequencer.
To me, it goes back to how regular movies are made. First, the footage is shot. Then, it is assembled into a picture, and the rest winds up “on the cutting-room floor.” (In the world of CG, of course, it is a little bit different: first the “animatics” are shot, then they are cut to make the finished picture, then those animatics are replaced one-by-one with their high definition renders … the so-called “edit, then shoot” workflow.)
The render outputs should be looked-upon as components. Render each one into a “MultiLayer” file. Once you’ve got all of the components prepared (generated…), as an entirely separate step you assemble them.
Thanks for sharing sundialsvc4