Summary: When you try to import raw MP4 files to iMovie, you may find the there are some importing or editing issues. Read on the article to get the solution.
We usually saw iMovie users encounter importing issues when attempting to edit MP4 files with iMovie program on Mac OS X. Let's see some frequently asked questions on this:
Q1: "I downloaded many MP4 movies from Internet, and want to import them into iMovie for editing to create a new movie.But the iMovie won’t accept the mp4 videos. Can you help me?"
Q2: "For some reason iMovie '11 won't let me import videos. Specifically, I'm trying to add MP4 files that I copied to my hard drive from my GoPro HD 960. For GoPro users, I used the R2 (720p) format. They open properly in QuickTime and VLC but can't be imported into iMovie (or iPhoto)".
In usual, we would like to use Mac tools iMovie to edit MP4 videos, including YouTube MP4 videos, iTunes MP4 videos, GoPro HD MP4 videos, etc. in order to get better videos or more wonderful video files. Well, iMovie might not work with some MP4 files sometimes due to the codec issue or other reasons. In this case, to smoothly edit MP4 in iMovie 8/9/11, the easy workaround is to convert MP4 to Apple InterMediate Codec .mov which is the best codecs with best results when working with iMovie.
If you have got MP4 clips and suffered the headache from dealing with these files, the program Brorsoft Video Converter for Mac, a top MP4 to iMovie Converter, which will get you out of trouble effortlessly in editing .mp4 files in iMovie 08/09/'11. With it, you not only can easily transcode MP4 to Apple InterMediate Codec .mov for iMovie program within a few clicks, you can also encode common videos AVI, WMV, MKV, VOB, FLV, or camcorder videos MTS, MXF, MOD, H.264 MP4/MOV to AIC for iMovie/FCE, Apple ProRes for FCP, DNxHD for Avid Media Composer, MPEG-2 for Adobe Premiere Pro, etc on Mac OS X(Lion, Mountain Lion included). I have used it to covert many H.264 MP4 files on my MacBook. It works fast and keeps the original quality in 1080 30p/24p.
[How-to]: Transocde MP4 video to AIC for iMovie
Step 1: Install and run Brorsoft’s Video Converter for Mac, and then click "Add files" icon to import your MP4 files to it. This video convert app supports batch conversion.
Step 2: Hit the Format box to select the specially designed video codec for editing in iMovie: iMovie/FCE --> Apple InterMediate Codec(AIC) (*.mov).
Step 3: (Optional) Adjust the video and parameters, including the Bitrate of Video and Audio, Audio, Video Size, Sample Rate, Frame Rate, Audio Channels, etc., by clicking the Settings buttion on the main interface.
Step 4: Click the arrow button to start transcoding MP4 to AIC for iMovie as well as Final Cut Express immediately.
After the MP4 to AIC conversion finished, you can easily transfer your MP4 media to iMovie for further editing without any problem.
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Source:Edit MP4 files with iMovie program on Mac OS X