is MPEG Streamclip. I think it's similar to VisualHub (which I haven't tried), but it's free: http://www.versiontracker.com/dyn/moreinfo/macosx/24055. Not sure if they've included a preset for TV configuration, so you may have to set the parameters manually. I've used MPEG Streamclip a lot, and it works well, especially for the price!
"convert mpeg to appletv on mac" this is easy to do, try this one : 4Media Apple TV video converter for Mac, i use another converter for mac, haven't tried this one , but i know it supports converting mpeg to apple tv.