Using the loopOut() expression always leaves the last frame blank, no matter what I do

I found one thing that may create empty frame.
If you have frame rate 29.97 change it to 30.

That solve my problem.

I've just had the same issue. I only get a single blank frame on the first loop around so it has to be a bug. I ended up just duplicating my comp for that single missing frame. Simple solution this time but I hope Adobe fix this bug.

I am using loopOut() after enabling Time Remapping and at the end of the comp (which i'm trying to loop) I get a black frame, therefore I have selected the comp and in the timeline at the second diamond shape for the Time Remap (the last frame the Black one ) type in one less frame. exp: the comp which you want to loop is 215 frames therefore you can go ahead and type 214.

That solve it for me I hope it will do for you.

Just to confirm, I'd be messing about with keyframes for the last hour. I had a 24 frame animation had tried every which way... described in tutorials on YouTube in other threads on here. Using the pingpong method worked. But I wanted to get the cycle working as well.

As soon as I turned on the 'continuously rasterise' icon it worked like a charm.

In my case, moving time remapped frames resulted the last frame before 00:00:00 being blurred."Toggle hold keyframe" couple frames before the last worked for me.

I found out I can use the loopOut() expression on another composition with the new keyframe method outlined above, and it fixed the blank frame.

The same method does not work on the original composition in question, for whatever reason.

Fortunately, the loopOut("ping-pong") expression you mentioned will work for this animation, and that does remove the blank frame.

This is normal behavior. Don't delete the keyframe at 16. Let me explain.

Let's say you have 2 keyframes for transparency. Frame 0 is 0 and frame 10 is 100. Adding the loop out expression to these keyframes will give you the following:

Frame Opacity

0 = 0

1 = 10

2 = 20

3 = 30

4 = 40

5 = 50

6 = 60

7 = 70

8 = 80

9 = 90

10 = 100

11 = 10

Then frame 19 will be 90 and frame 20 will be 0 and so on. This is because the animation loops between frame one and frame 10 which means it only reaches the value of frame 10 the first time through the loop. Every time after that the loop starts over at the first frame of the loop (frame 10, 20, 30 and so on).

This is normal. If you want frame 11 to be 0 then you'll need to add a keyframe there so you have an 11 frame loop instead of a 10 frame loop.

To solve your problem try backing up 1 keyframe from the end, inserting a new keyframe, and then leaving the last one. Now you have a seamless loop of all of your keyframes.

Does that make sense? The loopOut() method loop is exactly the same length as the keyframes to therefore the next frame after the loop has the same value as the second frame after the start of the loop and all subsequent loops will end one frame before the last keyframe. To make a continuous loop from 0 to 100 you need 3 keyframes. One at 0, two at 100 and 3 at 0.

You can also change the loopOut method from the default "cycle" to "pingpong" by writing loopOut("pingpong"). This would give you a smooth fade up and fade down between 0 and 100 because the loop goes back and forth between the first and last keyframes.

This is the way looping functions work in Java, 3D apps, and everywhere else that I have used them.