Yes, AAC is also patent encumbered, but the structure of the fees was apparently "better" for Apple. This was heavily discussed … Jesus, 15 years ago now … when

Yes, AAC is also patent encumbered, but the structure of the fees was apparently "better" for Apple. This was heavily discussed … Jesus, 15 years ago now … when everyone was pissed Apple didn't use MP3s. Basically, AAC was cheaper for Apple so that's what they used. But AAC was as "open" as MP3 and there was never any "lock in".