To play AAC files (which also are the audio tracks of MP4 in most cases) mp3DirectCut needs the
free libfaad2.dll in its folder. See the the More page for download links. MP4 audio need to be
demultiplexed to AAC. This can be done automatically with the free ffmpeg.exe and its location added in the
mp3DirectCut Decoder settings. AAC will not be multiplexed back to MP4.