Here is how to convert MP4 files and work with them in FCP

[Rafael Amador]

[Zoe Weslowski] “I did go back in to QT as you mentioned and exported it. I changed the compression setting to Apple Pro Res 422 (Proxy). I was able to get a file that I could import into the time line without red rendering, but there was a green bar there. “
Go for Prores or Prores HQ.
If you are converting with QT, set Audio “PCM/48Khz”.

If you transcode with MPGstreamclip:
In the audio make sure is at 48Khz (default for FC).
Make sure as well that frame size is 1280×720 (unscaled) and you uncheck “Interlaced scaling” and that the “Frame Rate ” window is empty.
Rafael

http://www.nagavideo.com

[Happy Boybaby]

Just google search Step by Step Guide on How to Convert MP4 to DV so as to Import MP4 into FCP/FCE

You will find a detailed guide on how to convert and import MP4 to FCP/FCE:

It is dead easy to import MP4 into Final Cut Pro for editing with the following guide.
It applies to MP4 recorded from various camcorders like Samsung HMX-H100 camcorder, Sanyo XACTO HD1000 Full HD camera, Flip camcorder, JVC GY-HM100, JVC GY-HM700 and more.
It applies to MP4 from media players, mobile phones, portable devices and YouTube etc.
It also applies to import MP4 to Final Cut Express and iMovie.
It applies to import MP4 to Final Cut Pro X or import MP4 to Final Cut Pro 7 or import MP4 to any other version of Final Cut Pro.

[New Peter]

As we know, Final Cut Pro is a non-linear and non-destructive editing software application, it can only import non-destructive video format including DV, HDV, P2 MXF (DVCProHD), XDCAM, and 2K film formats. Nevertheless, the widely used MP4 is lossy format, which is a final delivery file type and is heavily compressed. In order to successfully import MP4 to Final Cut Pro, we have to convert the lossy MP4 to non-destructive format like DV which is compatible with FCP.