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Davinator
11th September 2008, 19:48
Hello all. I am trying to have an overlay that will track the motion within a clip. Basically, I want to pick a position on frame x, have that position tracked for a few seconds, and have the overlay move based on the movement.

My intial thoughts when thinking of how to do this would be to somehow use mvtools to analyze the movement, and send that data to my overlay function. Unfortunately my mvtools knowledge is limited, and I have no clue how I would send that data to the overlay function.

Does anyone have any thoughts or suggestions on how I could accomplish this? Thanks!
tin3tin
12th September 2008, 11:06
Some inspiration, maybe for a new plugin?
http://www.gamedev.net/reference/programming/features/imageproc/page3.asp
hanfrunz
12th September 2008, 11:50
tracking is a difficult task, and most the time you have to manualy correct the path. So the only chance is see, is to use an external tool (apple shake, after effects, ...) to create a path and the use a not yet existing avisynthfilter which uses this path to do whatever you like.

hanfrunz
Comatose
13th September 2008, 03:06
Instead of a "path", you could render (in After Effects) a black box or something that stays on where the overlay should be, then use that black box as a mask with mt_merge.
Fizick
13th September 2008, 07:05
first part (tracking) may be done with a modified MVDepan (or DePanEstimate) with some finite (and moving) window around object.
Didée
13th September 2008, 16:43
Just for clarification ... isn't that what "mode=2" of MVCompensate once upon a time was made for?

Mode=2 has been depreciated for a longer time now, and I never tried it while it was available ... the description "[mode] 2 means it recomputes the compensation, but it does it in-loop, meaning that the vectors will be applied to the last frame computed" never was crystal clear, but it sounds like it could be meant to make a compensation of the last compensated frame, i.e. "recursive" compensation, which is pretty much the functionality that is missing for cases like this here.
Fizick
13th September 2008, 18:32
old mvtools 0.9.9.1 is at manao site ;)

IMO, Daviantor ask for full-frame motion