Still images with transitions in FCPX not compressing properly in MPEG Streamclip

Hi,

I tried posting this in the compression forum but had no luck so I am hoping someone may be able to help me here! I’m working on a Mac, using Lion. I’m using FCPX (version 10.0) to put audio and still photos together. I then export the sequences into QuickTime using the Apple ProRes 422 codec. After that, I import the files into MPEG Streamclip to convert them into H.264, and again export them as QuickTime. I’m using the files in a web-based doc, so the smaller the file, the better. It has been working perfectly except for when I use the transition tool in FCPX to add cross-dissolves between the photos. This makes it so that for whatever reason, MPEG Streamclip doesn’t compress the files properly, the photos are all pixilated. Anyone have any idea why this is happening?

Thanks so much,

Nicole