I dont even know what this would be called…. Splitting the frame?

[Michael Szalapski]

I second Dave’s post (here’s the relavent help page on masks)
I heartily recommend the link he posted as well. It’s got links to tons of great tutorials and things that you will find useful. To start in AE you absolutely must have a solid knowledge of the basice before you can do all the really swoopy stuff.

– The Great Szalam
(The ‘Great’ stands for ‘Not So Great, in fact, Extremely Humble’)

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.

[Noelle Melody]

Hey Matthew,

I agree with the other two posts – you should read as much as you can about After Effects basics. Masking is a great way to simplify otherwise tedious work.

I’ll try to help if I can:
Once you bring both of your layers of footage into your comp, you can have one video on top of the other, it won’t matter which one. Let’s call them layer Left and layer Right since you are having the footage side by side.

Select layer Left and go up to your tool bar. There are two tools you can use to mask this, one is the Rectangle tool and the other is the Pen tool. You mentioned that the split is uneven, so you should use the Pen tool in this case. The pen tool makes points that you can draw around your footage (kind of like the Polygonal Lasso in Photoshop) and can be manipulated by dragging the points with your cursor. Once you draw the shape you want down the middle of your screen and up and around to split the footage, you have to close the shape you made – you’ll know it’s closed when you return back to the first point you made and has you hover over it, a little circle appears. Then click to close your shape.

You’ll notice that only the area that you drew your shape around is visible. That’s because your Mask is set to Add. If you click on layer Left and hit the “M” key (to reveal the mask) you’ll confirm that it’s set to Add. If you click Subtract, the area you selected will disappear, and the area that was previous invisible is now showing. All the other effects do different things you can read about, but for this project set it to Add.

Do the same thing for layer Right. you can move the points around and even set key frames for them if you need to over time. To do this, select you layer, hit “M” and unswivel the arrow. You’ll see 4 options – Mask Path, Feather, Opacity and Expansion. You can make a keyframe for your Masks by clicking the stopwatch on the Mask Path and change it to a Toggle Hold key frame by hitting:
ctr+alt+H (PC)
command+option+H (Mac)
You make them Toggle hold bc you don’t want your mask floating all over the place. You want it to move when it needs to and sit still when it needs to. For this project you not even need keyframes, but I included it just in case.

Hope this helps you understand a little bit more about masks.

Noelle