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Have you ever watched one of those Hollywood movies where you see somebody running down the street and then it goes into super slow motion? Well really what's happening with that, they were originally shot with a high frame rate camera. So super slow motion was created because, let's say, the footage was shot at 200 frames a second, and then they played it back at 30 frames a second. So you get a much slower motion. I think there are plenty of us that get lots of footage that wasn't shot with a high speed camera, but people still want to slow it down and speed it up.
And usually, as a rule of thumb, I like to think, okay, I don't want to slow my footage down slower than, 30% lower than it was originally shot. And that's just a rule of thumb, so I can create smooth projects. But before you can even deal with any of that, you need to have a base understanding of what the tools are, and how they function. So let's start by looking at our project here. If we look in the timeline, we have an MPEG-4 file and if we select it up in our Project panel, you can see it was shot at 23.976 frames a second.
Now it exists in a composition that is also 23.976 frames a second. So when we make changes, I don't want to slow this down much less than maybe 17 or 18 frames a second. Let's look at how re-timing actually works. When you select the layer in After Effects, there are time controls you can easily get to by going up to the Layer menu. Now we need to have the layer selected in the timeline. There we go. So now when we go to the Layer menu, we can go to Time.
Now within Time, there's an option for Time Remapping. But if you're just very quickly trying to play footage backwards, you can enable Time-Reverse Layer. Now let's see what happens with this. I'm going to scrub my playhead to about 2 seconds and let's have this footage play to here and then play backwards, and then play forwards again. So if I selected this layer, and went up under Edit, I could Split it, which now it exists on two different layers, and I'm doing this because I want this top layer currently to play backwards.
So let's rename that Reverse. So we'll select that, and press Return on our keyboards and say Reverse. Okay. Now move your current-time indicator down to around 4 seconds, and split the layer again. The key command to split the layer is Command +Shift+D or Ctrl+Shift+D if you're on a PC. Now let's rename layer 1, Turbines. I'm just leaving it the same basic name as 3 because we're not adjusting the time for that layer.
When you reverse a layer, it's literally going to reverse. So see this light gray area on the outside of what we've actually chosen to show. This is the area that got trimmed out. Well look at what happens when we go up under Layer, and go to Time, and choose Time-Reverse Layer. It's playing backwards and it literally flipped the entire layer around, but it knows we want to show the specific frames. So Now this front section that used to be over here is now over here.
You can see it's going to play in reverse because of these red lines. If we load up a RAM Preview, watch what happens. It's going to play, and then jump backwards and then jump forwards again. That's because these frames actually shifted around in the timeline. So let's select Layer 1 and duplicate it, so we have a clean layer to start with. I want to solo this layer, and then I'm going to bring its start point back to the start of the timeline by clicking and dragging on it.
In here, I want to show you how we can create a variable time remapping where it changes over time. In order to do that, let's go up to Layer > Time, and go to Enable Time Remapping. Notice when Time Remapping is enabled, I have a keyframe at the beginning and at the end of my footage. Now this is better illustrated when we select Time Remap in the timeline and then open up our Key Frame Editor. In here, you can see a line that represents how the footage plays.
As long as this line is at an angle going upwards, it's going to be playing in a "forwards" direction. Anytime that it's flat, it will be stopped or paused. So let's get started by moving our current-time indicator to 2 seconds, and going over to the left side of the timeline to add a keyframe here with the Keyframe Navigator. Go ahead and click right there, perfect! And now let's move to 4 seconds and add another keyframe.
Now we haven't done any Time Remapping yet, because we haven't made any adjustments to these keyframes. Select the second keyframe you added and drag it down in the timeline. You should notice snapping, if it's not snapping you want to toggle this magnetic button here. So with the magnet, it snaps. It's perfectly flat compared to the other keyframe. If I drag that up and down, it will be flat. So what's going to happen when we preview this? It will play forwards in normal time at the front section, and then it's going to pause, and then play back a little bit faster.
See how this angle is steeper back here? That's letting me know it has to play faster. So there, it stopped, and then there, it picked up again, but it's playing at a faster rate, and we stop playback. If you want to round this out, what you can do is right-click on the layer, go to your Keyframe Assistant, and choose Easy Ease. That will give you your handles. So let's do that for the next keyframe. Right-click on the keyframe > Keyframe Assistant > Easy Ease.
Notice how smooth it made the second handle. That's just because it's trying to ease it back into that higher velocity. So if we press Home and load up a RAM Preview again, you should notice it easing in, pausing, and then easing back out in terms of the motion. It may take a second to load on your system. Don't worry, it will get there. All right, I'm going to press the Spacebar so I can watch my RAM Preview for what's cached so far. Now as you can see, I'm getting some stuttering that's happening and that's just because it's playing at such a low frame rate.
Let me stop playback one more time. Just so you can see what it looks like, let's click on the second keyframe and drag it all the way down. Now notice, when I hover my mouse over the keyframe, it's telling me I'm at 4 seconds, but the Time Remap is saying play the frame from 0 seconds at this point. If I hover over here, it's saying, play frame 2 seconds at 2 seconds. So let's load up another RAM Preview, and you'll see it speed up, slow down, and speed up again.
(video playing) Okay, so now you've seen what it looks like when it speeds up, goes in reverse, and then goes back. Just understand when you adjust your keyframes forwards or down the timeline, you will be changing how fast the frame rate changes because the curve will have to change accordingly. If you wanted to smooth out an individual section, you could draw a lasso around the keyframes that you're trying to adjust, and you'll get this bounding box that pops up if you have this key active.
This bounding box will allow you to drag the keyframes out in proportion to each other. Just to understand when that smoothes out, notice how sharp this angle is. Okay, so that brings me to the last thing we're going to talk about with time remapping. Let's close our Keyframe Editor, go up under Layer > Frame Blending. In here, you have Frame Blending options. So as you remap your footage, sometimes you'll notice that it stutters or it looks a little ragged.
That's because Frame Blending is off. Frame Mix is the next step up from being off, where it mixes frames by adding or creating new frames, and then, Pixel Motion will not only add and create frames, but it will actually analyze each individual pixel between the frames to create the smoothest motion possible. Just understand when you choose this, it's going to add a lot more time to your render time. But I can tell you the rewards are well worth the wait. Now you understand how time remapping works directly on the layer, there's one other area where there's time remapping you should check out in After Effects, and that's in the Effects area.
So go to the Effects > Time, and then you can see there's a whole host of different effects that you can apply to layers to make time adjustments. If you would like to explore time remapping and time adjustments more in depth, you should check out another title on our library called After Effects Apprentice 10: Time Games.
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