Time Remapping

If this is your second day with After Effects then go here: User Guide

After you have gone through the first set of Get Started tutorials at the top you'll have a basic idea of how the UI and the workflow work. Just jumping in and poking around or thinking of something you want to do and pushing buttons is almost always a waste of time. Don't be afraid of the User Guide and the Search Help field in the top right corner of AE.

When you ask questions a screenshot showing the modified properties of the layers that are giving you problems helps us to help you. To show what you have done to a layer just type uu quickly.

If you want to keep sections of a time remapped layer playing in Real-Time you have to set a keyframe at the start and end of the realtime section then make sure that you select both of them so the distance between them stays the same and drag both of them left or right in the timeline to slow down or speed up the video before or after the two selected keyframes. If you are trying to use time remapping on a video clip that has been trimmed so the entire shot is not in the comp make sure you pre-compose the video layer, moving all attributes and trimming the pre-comp to the in and out points of the layer before you apply time remapping. This is the setup:

This shows the Main Comp timeline and the pre-comp timeline after Time Remapping is applied and the real-time section is defined:

For this project I want the first part of the video to be fast motion and the last part to be slow motion so the center section is moved like this:

Switching to the graph editor and making sure the value graph is selected gives you a good way to judge the speed of the video and even lets you ease in and out of the speed changes. The slope of the value graph is key to understanding what is happening to the speed of the clip.

One of the normal behaviors of time remapping that gets a lot of people in trouble is that the last keyframe applied when you enable Time Remapping is placed after the last frame of the layer has played. That means there is nothing in that frame. The solution is to move back one frame, set a new TR keyframe, then delete the original keyframe.

That should get you started and give you the tools you need for any time remapping problem you may run into. The only other thing you need to consider is the three different options for frame blending. It's almost always a good idea to run tests on all three options for a video that has been slowed down. A video that has been sped up usually benefits from adding pixel motion blur and turning frame blending off, but it all depends on the shot. You really need to run some tests to figure out which solution is the best.