I import .m4v files to FCPX and edit it very little just trim and title it, then I export with Current setting and H.264(2 try), but when I watch the finished file, I can hear little popping sounds constantly over all time. the original file doesn't have that sounds. So I try using iMovie and it has no problem. I don't know if there was a problem in FCPX or my problem. Please let me know if I can fix in FCPX. Thanks in advance.