Help with "masks"

[Snowfun]

Hi,

I'm new to all this so apologies if this is a trivial question!

I'm looking to create a shot with time-lapse sky/clouds against a normal speed foreground. I can achieve a reasonably horizontal and "simple" horizon - but it isn't a "straight line". The "foreground" (normal speed) shots would be tripod based. There are then two alternatives:

1. foreground action taking place under the horizon (i.e. not impinging on the sky or time-lapse space) 

2. foreground action takes place above the horizon.

I assume that I need a mask to achieve this? But my question is what is the best tool for this? I use FCX as an editor but have failed dismally to get to grips with Motion. 

Any advice much appreciated.

Tim

[Santiago de la Rosa]

Masks work very good in After Effects.

There are lots of tutorials of masking, it´s not dificult.

https://helpx.adobe.com/after-effects/using/creating-shapes-masks.html

https://helpx.adobe.com/after-effects/using/alpha-channels-masks-mattes.html

 

In the composition, place down the "under the horizon" file 1 and up the "above the horizon" file 2.

Mask the file 2 with the pencil or rectangular tool the from the "simple horizon" to the end of the frame (the part of the video that you don´t want in)

And in the mask menu, select Substract (You see Normal, Add, Substract, etc).

You will see now the file 1 frame and file 2 frame, one above the other.

Here you can see how: https://www.youtube.com/watch?v=OzAkb7Cw0uM

(Sorry for my english.)

[Snowfun]

Thank you. I have AE as part of CC so I'll look into it. I have also found the "draw a mask" tool in FCX which gets round preset shapes and looks to do what I need.