I have been using older VHS to DVD software and hardware to copy over my old DVD collection for granddaughter to view on iPad. Before Mavericks and iMovie 10, I was able to choose a variety of output sizes. I always ended up taking the 960 x 540 dimensions. With iMovie 10, I am finding the output is always 640 x 480, even if the imported size is larger. I see that other sizes are grayed out. I realize the device I am using to copy if not HD, but I don't know why I am now limited to a smaller size output. Any ideas?