Getting height and width of swf file before loading- as2

Question

I am implementing progressive loading of swf document file. For this I need height and width of the swf frames while loading the document.

I have tried

mclListener.onLoadProgress = function (target_mc, numBytesLoaded, numBytesTotal)
{
    swfwidth = target_mc.width;
    swfheight = target_mc.height;

};

But this returns value 0. I know these values work well with mclListener.onLoadInit() but I want the width and height while loading the document. Is there any possible way?