File Juicer
File Juicer for macOS
Overview of Formats

Search & Extract

Images

jpg jpeg 2000 gif png pdf wmf emf tiff eps pict bmp

Video

mov mpeg avi wmv

Sound

mp3 wav System 7 au aiff

Text

ascii rtf html

From:

avi cab cache chm dmg doc emlx exe ithmb m4p mht mp3 pdf pps ppt raw swf wps xls zip and other formats

m4p and m4a AAC files from iTunes

Apple Music
File Juicer can extract artwork from m4p, m4a and mp3 files. You can also extract a bit of text, just like from ID3 tags in MP3 files, with the added bonus of discovering that your name is in the file too, if you bought the file. To take a further look into what is in your iTunes Library, you can take a look at Automator which has actions for controlling iTunes.

Apple recommends that you protect your investment in m4p files by backing up your library.

AAC files are the naked audio without artwork etc. It makes no sense to drop those on File Juicer.
M4A files are AAC files with cover art and other meta tags.

Using iTunes libray with Roon

Roon

If you are importing your music from iTunes into Roon and have more than one image per album, you will normally only get one image over. Fortunately Roon can handle extra images if you place them in the same folder as the audio files.

AAC - Advanced Audio Coding

While it is now mostly known from the iTunes music store AAC is an ISO standard.