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How do I put a mask for a set period(time)?

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Jasmine KimHow do I put a mask for a set period(time)?
by on Apr 10, 2013 at 4:34:50 am

I'm very very new to after effect so please be patient.
I do have understanding of general logic of how AE works i.e photoshop related, key frame, etc.

What I'm trying to do is simply putting the mask for a set time.
I made a mask and I want it to last only 1 or 2 seconds in the video.
So I put time-remapping but I don't know how to make the mask disappear at the 2nd key frame.

This must be very simple and easy thing to do.

Also, I wonder if there's a separate window (sort of zoom window) to control keyframe like in Premiere.
Like the one you can see detail and set detail info of a certain spot that you put 2 key frames at the beginning and at the end.

Thanks in advance.


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chris brettRe: How do I put a mask for a set period(time)?
by on Apr 10, 2013 at 8:05:15 am

Hi ---

---it would be easier to watch a training video than have me explain - those guys do it a lot better than me ..............

--- suggest Andrew Kramer at Videocopilot.net / tutorials / basic tutorials or trawl Andrew Devis's tutorials on this site .



These 2 guys have different styles and if used together are a brilliant training system I think - highly recommended - worked for me.


--------------- all the best ----chris --


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Jasmine KimRe: How do I put a mask for a set period(time)?
by on Apr 10, 2013 at 8:29:46 am

Hi
Thanks for the post.
For the past 2 days, I watched a looooot of tutorial videos on youtube and vimeo but still couldn't figure out this specific issue.
I get how things work. But for some reason it doesn't work when I try to apply those methods to what I'm creating.
I just want to mask a small part of the video screen and release the mask after a second.
Wow, how hard this can be?!


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chris brettRe: How do I put a mask for a set period(time)?
by on Apr 10, 2013 at 12:19:52 pm

---- ok - easy one ..... either ........

1 ) Apply the mask to an adjustment layer and alter transparency of the adjustment layer ( should work not tested it )

2 ) Apply the mask to a layer of solid white and use it as a track matte - animate tranparency of track matte over one second - this will definately work.

--------------------- and thats it ---



------------ chris ---


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chris brettRe: How do I put a mask for a set period(time)?
by on Apr 10, 2013 at 12:33:15 pm

Hi Jasmine -

- sorry easiest way is to animate 'mask opacity' in the drop down menu that displays the mask settings -- ( brain temporarily off-line ) ...

------ this should sort it -------chris --


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Christopher TravisRe: How do I put a mask for a set period(time)?
by on Apr 10, 2013 at 12:00:19 pm

I'm only a baby AE user myself, and I don't have it in front of me so can't test it, but if you're in a hurry here's a thought for you to try.

I've tried to switch masks on and off and never worked it out myself. What you could try is using another shape object AS a mask. i.e.

make sure you have no layers selected, then with the pen/shape tool, create the shape of your mask (let's call this layer A).

Make it 100% white and position it where you want it.

in the timeline place it directly above the layer you want it to mask (lets call that layer B)

on layer B, in play with the options in the "matte" drop-down menu. I can't remember exactly whats in there, but they are options for using the luminosity or alpha channel of the above layer, to mask the layer below.

If none of those work, try playing with the blend modes of Layer A.

As I say, I'm only a beginner myself which is why my advice is so vague but I think if you play around in that general direction you'll get what you need. Obviously then, you can switch Layer A on and off at will.


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Walter SoykaRe: How do I put a mask for a set period(time)?
by on Apr 10, 2013 at 12:45:33 pm

[Jasmine Kim] "What I'm trying to do is simply putting the mask for a set time. I made a mask and I want it to last only 1 or 2 seconds in the video. So I put time-remapping but I don't know how to make the mask disappear at the 2nd key frame. "

Chris gave a great answer about animating the mask's opacity. Turn it up to 100% where you want the mask to apply; animate it down to 0% where you want it to turn off.

If you want it to "click" on and off, that's a great use for hold keyframes. Select your keyframes, right click and choose "Toggle hold keyframes." This will cause a keyframe's value to be held until the next keyframe -- so if you have a hold keyframe of 100 at frame 0 and a hold keyframe of 0 at frame 10, there will be no animation between. Frames 0-9 will all be 100, and frame 10 will switch to 0.

Animating time-remapping alters the time of the underlying layer itself, but not any keyframes you've applied to the layer in the main comp. If you wanted those animations to be affected by time-remapping, you'd have to precompose first.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
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