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The Advanced Audio Coding (AAC) file format is a lossy digital audio encoding format. Files downloaded from the iTunes Music Store are available in this format.


AAC files usually have a file ending of .m4p and contain lots of metadata. The output of the Unix strings command suggests that at least the following information is contained:

  • Name of the person who downloaded the file from the iTunes Music Store
  • Email address of that person (sometimes)
  • Timestamp of when the file was downloaded
  • Another timestamp (probably the date when the file was put into the iTunes Music Store?)
  • The usual metadata of music files (artist, album, cover art etc.)