AAC [1] has never been an Apple format, though in 2004 it was less ubiquitous than it is now.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Advanced_Audio_Coding" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Advanced_Audio_Coding</a>