Getting Layer Duration in Photoshop Timeline

I wanted to decrease the outTime of all the layers to some value. What I ended up is decreasing the layer OutTime to zero and then increasing it back to where I want it to be. It appeared to work as an action. So I made the script.

Here is the final script to make all layers in th timeline be 1 second long:

var doc = app.activeDocument;

function ExecuteOnAllSets(item) {
    ExecuteOnAllLayersInSet(item, Action);
    
    var i = 0;
    while (i < item.layerSets.length) {
        ExecuteOnAllSets(item.layerSets[i]);
        i++; 
    }
}

function ExecuteOnAllLayersInSet(set, f) {
    var i = 0;
    while (i < set.artLayers.length) {
        SelectLayer(set.artLayers[i]);
        f();
        i++;
    }
}

function Action() {
    ChangeLayerTLLength(-90, 0);
    ChangeLayerTLLength(1, 0);
}

function ChangeLayerTLLength(seconds, frames) {
    var idmoveOutTime = stringIDToTypeID( "moveOutTime" );
        var desc8 = new ActionDescriptor();
        var idtimeOffset = stringIDToTypeID( "timeOffset" );
            var desc9 = new ActionDescriptor();
            var idseconds = stringIDToTypeID( "seconds" );
            desc9.putInteger( idseconds, seconds );
            var idframe = stringIDToTypeID( "frame" );
            desc9.putInteger( idframe, frames );
            var idframeRate = stringIDToTypeID( "frameRate" );
            desc9.putDouble( idframeRate, 30.000000 );
        var idtimecode = stringIDToTypeID( "timecode" );
        desc8.putObject( idtimeOffset, idtimecode, desc9 );
    executeAction( idmoveOutTime, desc8, DialogModes.NO );    
} 

function SelectLayer(layer) {
    doc.activeLayer = layer;
}

(function main() {
    ExecuteOnAllSets(doc);
})();

Getting Layer Duration in Photoshop Timeline

Someone who know how to modify AM code might be able to do it. I tried working with the timeline once and asked an Adobe engineer about it, and all he replied as, "It's black magic."

I don't think they are officially documented anywhere "for reasons".  The UI callbacks are probably everything you are ever going to get from this self-contained bubble.

Mylenium