by JonnyPhoenyx » Thu May 03, 2012 3:25 pm
Yeah, FCP doesn't play well with mp4 or anything that uses the H.264 codec. You would need to uses compressor or MPEG-Streamclip (my preference) and convert it to another FCP friendly codec such as Apple ProRess 422, HDV, or in rare cases DVC-Pro. This all sounds complicated, but FCP is meant to be used for professional businesses that operate in high capacity files sizes and qualities. So I could make my FMA AMVs, I burned up nearly 600GB in Apple ProRess files. That codec will give you little to no errors during editing.
So, to answer your question: Don't use MP4. Use the .mov container and a codec such as HDV or Pro Res. They take up a ton of space, but you have the best quality and fewest editing issues.