I discovered by accident that my 10-year old car's entertainment system can accept .aac suffixed files on USB flash memory sticks to play. But when I tried to play an ISO9660 data CD containing AAC files instead of MP3 files, it said it could not find any MP3 files on the CD.
Since it's the same entertainment unit which also accepts input from Bluetooth, and analog AUX 3.5 mm stereo jack for a total of 4 input sources, it seems strange that it can handle AAC files, but only from the USB flash memory.
I tried naming the files suffixed as .m4a. No joy, still could not find any MP3 files on the CD.
Ok, I'll try to fool it. I renamed the AAC files to have .mp3 suffix. Now it doesn't complain that there are no MP3 files, but regards them as invalid, skipping through them without playing.
From this I infer that there are at least two decoder paths, the one for the CD drive that can only play MP3 files, and the one for the USB flash memory that can play both MP3 and AAC.
Incidentally I think this might be the last car player I own that will play CDs. For my next car I'll probably play from USB flash memory, or from my phone via Bluetooth. These days when you mention CDs to people below a certain age, they go: what?
