EXPORTING to mp4 hd video - poor quality

Hello, i have the latest imovie, and a brand new macbook pro, all updated. I am trying to export a movie as a mp4 using the h.264 encoding in HD quality. When it's all done exporting the quality is really really bad.

Any advice as to what i'm doing wrong? The whole point is so that i can play hd movies i have made on imovie on a playstation, .mov are not supported