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The After Effects Apprentice videos on lynda.com were created by Trish and Chris Meyer and are designed to be used on their own and as a companion to their book After Effects Apprentice. We are honored to host these tutorials in the lynda.com Online Training Library®.
- Grouping layers by nesting and pre-composing
- Identifying and solving render order issues
- Navigating composition hierarchies
- Editing a precomp while viewing the result in another composition
- Preserving the frame rate of a nested composition
Skill Level Intermediate
Trish Meyer: In the last movie, I took a boring gray apple and I used it as a matte and filled it with a colorful movie. Although I did end up with the look that I wanted, in this movie I'd like to recommend a different workflow. As a general rule, I do want to create a pre-comp with a track matte and the fill all composited together. That gives me the utmost flexibility so I can apply effects or keyframes to the matte and the fills separately and in the main comp I can apply keyframes and effects after the track matte has been composited.
So if you are following along, I hope you didn't save the project, because we're going to revert back to the original project. And we are going to build it in a different way and that should bring me back to exactly where I started with the Red Apple Starter comp and my boring gray apple. So I'm working away and I have this great idea that I could make this apple more interesting by adding a fill movie and let's just look at a couple of things here. We have our composition, and you'll see it's five seconds long and it's a DV size and if I click on the Apple movie, notice that it's eight seconds long and 59.94 frames a second.
The wireframe apple is rendered from a 3D program the twice the frame rate. If you have the rendering time, it's actually a great idea to do that. That way if you do decide to field render this animation, you'll have a nice clean frame for every field. Now maybe you just decide it's animating too quickly by slowing it down to 29.97, your 8 seconds could become 16 seconds a material. The movie we'll going to use a fill is the Light Illusions movie from ArtBeats and that's a DV1 size and its 10 seconds long.
So I've this great idea, like to use this movie to fill the apple, but instead of adding this movie directly to my main comp, a little warning bell is going off right now and I am saying to myself I want to create a track matte composite. I need to do this in a pre-comp and if I add this movie to this comp and pre-composed both layers, I'll be stuck moving all the attributes. So let's put that back and let's do it this way. What I'm trying to do is very simple. I'm trying to leave all of my keyframes here including the effects, the Drop Shadow, and Wigglerama, and I want to create a track matte composite that renders before all these attributes.
Remember that's key, because if my track matte renders first my scale animation will be applied to the final composite and the random wiggle animation will also be applied to the composite. I also won't have any issue with the Drop Shadow changing color. So here's what I would recommend. When you get that great idea to add a track matte to a layer, select it and go Layer > Pre-compose and notice that you now have a choice. You can select either option, Leave all attributes or Move all attributes.
The Leave all attributes option is only available when you have a single layer. So let's read the fine print. The Leave all attributes option creates a new intermediate composition with only the wireframe apple in it. The new composition will become the source to the current layer. Well that sounds promising, but we do need to give the pre-comp a useful name. So let's call this apple + matte. Even though I haven't created the track matte yet, I'm going to do it in just a moment and since I want to edit the pre -comp, I'm going to leave the Open New Composition enabled.
We'll click OK and look what happens. A completely different result than Move all attributes. If I select the apple, you can see that the comp is the same width and height as the apple movie. It's also the same duration, eight seconds, as the apple movie and if I open Composition Settings, you can see that the Frame Rate is 59.94. It's also Square Pixels. Now I'm using CS5.5. In earlier versions you may notice that when you pre-composed using leave all attributes the Frame Rate maybe set to match the main comp. So do check that in case it's important.
In this case I don't think it matters that is 59.94, but just in case I want to RAM preview. Maybe I'll change it to 29.97 so that it will match the film movie. I'll click OK, return to 0 and let's drag in our movie. Again it's a track matte composite. So we want to make sure that the fill is below the matte and you can see the movie is quite a bit larger, so I can either scale it down and position it to fit or I could use any of the handy Fit to Comp options under the Layer > Transform > Fit to Comp, Width or Height. Let's just try Fit to Comp. There we go.
So that's how that's going to line up and we'll select Alpha Matte and now the movie we'll play inside the alpha channel of the wireframe apple. That was easy. We'll go back to our main comp. So here's our apple scaling up with the track matte composite already rendered. The only thing that's a little annoying is every time you pre-compose, it twirls up the twirly. Because I have Wigglerama applied, if I press U to see all the keyframes I see too much information.
So I'm going to press E for Effects and then Shift+S for Scale and Shift+T for Opacity. So as you can see when I pre-compose with Leave all attributes, all of my keyframes and effects are still in the main comp. Also notice that I don't have a blank area in my layer bar. My pre-comp starts at one second and that synchronizes to frame zero in my pre-comp. I can see all eight seconds of the apple. So in the main comp, if I need to use some other part of the movie, it's still there.
Or if I decide to make this composition longer, let's say I want to extend it to six seconds, I don't have to go down to the pre-comp and make the pre-comp longer. That's another advantage. So I hope you can see that this workflow is a much more straightforward way of adding a track matte when you're in the middle of an animation and you get a great idea.