When files are muxed, they contain interleaved audio and video tracks (they're mixed together instead of stored in separate tracks). Because of this, iMovie cannot support them.
Important: iMovie ’08 does allow the import of MPEG-2 when imported directly from supported cameras. Exporting MPEG-2 clips imported in this manner will not lose audio when the export is performed from within iMovie ’08.
If you want to find out if a movie file is "muxed," follow these steps:
- Open the original movie file in QuickTime Player.
- From the Window menu, chose Show Movie Info.
- Click the More Info disclosure triangle in the Movie Info window (if it's closed).
- Note the entry next to "Format."
If the format is "MPEG1 Muxed" or "MPEG2 Muxed," you can't use the clip in iMovie. You may want to consider using a third-party utility to convert the clip to DV format for use in your iMovie project.
Note: If you have the QuickTime MPEG-2 playback component installed, it may not change the issues described above. Editing muxed MPEG-1 and MPEG-2 files is not supported in iMovie, even with this component installed.