Marker Sync - After Effects Expression by Animoplex

marker-sync.js

// MARKER SYNC
//
// Allows you to trigger playback of precomp segments using markers.
// This allows you to change timings without diving into precomps and makes it easier to reason about your project file.
//
// 1. Create a precomp A with a layer called "Controller"
// 2. Add named markers to the timeline within Controller.
// 3. In the parent comp, enable Time Remapping for the precomp A
//
// Modified expression based on Dan Ebbert's Marker Sync Expression
// Original Version: http://www.motionscript.com/design-guide/marker-sync.html
// Full Tutorial: https://www.youtube.com/watch?v=B_3XS2-VWOM&t=698s

src = comp(name).layer("Controller");
n = 0;
if (marker.numKeys > 0) {
    n = marker.nearestKey(time).index;
    if (marker.key(n).time > time) {
        n--;
    }
}
if (n == 0) {
    0
} else {
    m = marker.key(n);
    myComment = m.comment;
    t = time - m.time;
    try {
        mark = src.marker.key(myComment);
        if (src.marker.numKeys > mark.index) {
            tMax = src.marker.key(mark.index + 1).time - mark.time;
        } else {
            tMax = src.outPoint - mark.time;
        }
        t = Math.min(t, tMax);
        mark.time + t;
    }catch (err) {
        0
    }
}