AAC format is compressed lossless audio format, and AAC seems to be the right choice to replace MP3 rather than FLAC - a completely different format not using digital audio compression.


Format Description
aac Advanced Audio Coding
mp3 MPEG-1 Audio Layer 3
m4a MPEG-4 Audio Book
wav Waveform audio format
ogg Ogg Vorbis Compressed Audio File
weba WebA Audio File
wma Windows Media Audio
flac Free Lossless Audio Codec
m4b MPEG-4 Audio Book
ac3 Audio Coding 3