iMovie not importing an mp4 file that I want to edit

MPEG-4 doesn't tell me much. It is basically an Mp4 file. However, there may be some tiny codec in the MPEG file that makes it incompatible with iMovie. The audio format coupled with it can also be important. It should be AAC, although other audio formats will work, too.

Put the clip on your desktop and open it in QuicktimePlayer. Then do Window/Show Movie Inspector. A box will pop up showing the format. What audio and video formats does it show?

Also, take the clip and run it through the free download Handbrake to clean up any format issues. Do that even if the clip is shown to be Mp4/AAC.

You can get Handbrake here:

https://handbrake.fr/

A simple way to do it is to open Handbrake and do a File/Open Source. Navigate to your video and choose it as the source from the resulting screen. Then do File/Start Encoding. Wait a couple of minutes for the conversion to

complete. Then save and import the converted clip into iMovie.

-- Rich

The format looks fine from your screen shot. If you ran the clip through Handbrake and it still won't import, it is not a format problem.

Exactly what steps are you taking to import the clip and what happens when you try? Any error message?

Nothing to do but try some diagnostics per the below.

As for deleting preferences, you need first to close iMovie and then open it while holding down the Option and Command keys. Then you will get the box with the option to change preferences. If that's not happening then there is something wrong with your iMovie app.

Also, try creating a new project and see if the clip imports into it.

If still no luck, try opening iMovie in a new library, by first closing the app and then opening it while holding down the Option key. A box will appear with an option to create a new library.

Another thing you can do is reboot in Safe Mode. Boot up in Safe Mode and, after everything loads, immediately shut down and reboot in normal mode. Then see if iMovie works properly.

Start up your Mac in safe mode - Apple Support

Finally, you can try redownloading iMovie. To update/redownload iMovie 10, drag your iMovie 10 app from the Applications folder into the trash, but do not empty the trash. Sign in to the app store and open your purchases folder by clicking on your name at the bottom of the app store side bar. You will see your purchases displayed, including iMovie 10. Redownload/update iMovie from there. If not successful, drag your present iMovie app out of the trash and return it to the Applications folder.

-- Rich

If the clip's format checks out O.K. you can also try deleting/resetting preferences. To delete/reset preferences open iMovie while holding down the Option and Command keys and select to delete preferences in the box that appears. iMovie will open in a new empty library. Reopen your old library to get back to your projects. Now see if you can import your clips. Possibly you may need to reboot to set the changes.  Deleting preferences is a safe procedure that will not cause data loss or disruption to your project.

-- Rich

It must be Mp4/AAC to work in iMovie. Check the clips format.

— Rich

Try importing to QuickTimePlayer instead of iMovie. Also, you could try using the Image Capture app on your Mac to import to your desktop, and from there drag into iMovie.

-- Rich

Do you have enough free space on your drive to enable the import? The clip may be too large to import.

-- Rich

Regrettably, I have no idea what may be going on with your iMovie app. It is not functioning correctly.

Try contacting Apple Support and discussing it with the techs there. They have the capability of remotely accessing your computer, that we do not have here.

Best of luck with this.

-- Rich