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Forums Adobe After Effects Expressions Change precomp duration and inPoint of following precomps

  • Change precomp duration and inPoint of following precomps

  • Daniel Vella

    November 22, 2022 at 9:35 pm


    I’m trying to build a script that changes the duration of a precomp and any layers inside it from 1 second to x seconds as an example, while also moving the inPoint of any following precomps or layers so that they don’t overlap.

    Attached are two photos of what I want to achieve. I want to change the duration of precomp “Two” from 1 second to 2 seconds and move precomp “Three” to start from the 3rd second instead of the 2nd so they don’t overlap.

    I tried changing the inPoint and outPoint of the precomp, but it doesn’t seem to change. Any help or guidance is greatly appreciated.

  • Dan Ebberts

    November 22, 2022 at 10:57 pm

    This is very simplified and very specific to your example, but hopefully it gives you the idea:

    var mainComp = app.project.activeItem;
    var two = mainComp.layer("Two");
    two.source.duration = 2;
    two.outPoint = 3;
    var three = mainComp.layer("Three");
    three.startTime = 3;
    var twoComp = two.source;
    for (var i = 1; i <= twoComp.numLayers; i++){
    twoComp.layer(i).outPoint = 2;
  • Daniel Vella

    November 23, 2022 at 7:22 am

    Hi Dan, thanks for your reply. I’ve run your script and precomp “Three” was moved correctly, however, the duration of precomp “Two” changed to less than a second. Any idea why this could happen, please? Could it be that duration doesn’t accept seconds? Thanks

  • Dan Ebberts

    November 23, 2022 at 7:48 am

    Ah, I hadn’t noticed that your layers have been time stretched to 3.3%, so you’d have to factor that into the calculation of how long to set the duration of the source comp.

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