Comment 11 for bug 1706881

As explained on the wiki at https://www.mixxx.org/wiki/doku.php/troubleshooting#a_deck_randomly_stops_playing , converting from one lossy format like AAC to another like MP3 is not recommended. Instead, it is recommended to either use prerelease versions of 2.1 or convert the MP4 files to FLAC and keep the original files around, then delete the FLAC files when upgrading to 2.1.