MegaPixel

I have been trying to create a video slideshow site similar to Animoto.com or Slide.ly with little success. I want users to be able to upload their own images, and possibly music and then have a few options with transitions and text so that they can create their own video slideshows. I found some code in php that created a slideshow and had various effects, but it created it in a .swf format and looped with no way to just make a video. It was http://www.maani.us/slideshow/ The interface seemed pretty easy, but like I said, it looped and wasn't really created into a video format similar to .mp4. I am looking for direction on where to go to be able to create such a web app. I have looked with google for hours with little success. I just want something very similar to the way animoto.com works. User uploads, creates, and done. Very basic, and very simple. Please help!