

iMovie supports audio codec of MP3, WAV, M4A, AIFF, AAC, if you video files are encoded in other audio codec, such as ac3, dts, mp3, you can encounter the problem of no audio in MP4 video playback in iMovie. The problem is caused by the audio codec isse. The Reason why there is no sound or missing audio in MP4 imported in iMovie, iMovie for iOS iPhone/iPad and the Fix Though, MP4 is a supported video format for iMovie, many users find that MP4 video has no sound or audio after imported in iMovie (iMovie 10, iMovie 10.1.9, iMovie for iOS iPhone/iPad included). In the early post, TechiSky introduces the Best Video Format for iMovie, which is MP4, MOV, MPEG-2, AVCHD, DV, HDV, MPEG-4, H.264.
