Re: Why it wasn't working, and neither was your good advice...

[mikederk] "So, until I figured that out, nothing you were telling me was going to work. But it wasn't wasted -- now it works."

Yes it was... If you time-remap a 3 second layer you can drag the end of that layer out to infinity and beyond, so 20 seconds was definitely well within the reach. The last frame of the composition (according to Time Remap) will always be blank since Time Remap maps from the 0th frame.

That is to say, your composition had a duration of 3 seconds, which for my sake I'll call a 90 frame composition (you may have had it running at a lower FPS but that's not the point). However, in AE's mind your 90 frame composition runs from frame 0 to frame 89 (90 frames, but starting numbered at 0). If you enable time remapping on this pre-comp in another comp then Time Remap will allow the values 0;00 through 3;00 (and these are the defaults with a 3;00 duration footage item) but the frame at 3;00 is 1 frame beyond the end of your composition and so is blank! You must change the last keyframe to 2;29 and move it forward 1 frame in the composition (so that it resides at 2;29) then drag the end of the composition out as long as you want and apply the loopOut(); expression.

FYI, even if you leave the default time remapped values at 0;00 to 3;00, drag the out point out (as I instructed) and applied the loopOut(); expression, your comp would still loop properly... well... almost properly, it would just have 1 blank frame every 3 seconds (which can be remedied by the above process).

[mikederk] "However, once footage on the layer runs out, it stops looping, and then runs blank for 17 seconds. "

It has never done this using the process I outlined in my previous post. Time Remapping works just like any other keyframed property, if you had a layer that moved between two keyframes from [360, 100] to [360, 300] the layer would stop at [360,300] and not move any farther... the same is true of time remapping. My guess is that you either didn't apply the loopOut() expression after dragging the layer's endpoint out because you saw that the time remap had stopped at 3;00 (a blank frame) and was 'stuck' there... or that you didn't drag the end point of the pre-comp out beyond 3;00 (which you can do on a time remapped layer) and so the layer disappeared before it got a chance to loop.

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA