Oh, this is frustrating.
I buy my music from iTunes. This started when I had an iPhone, and even though I no longer have an iPhone, I find iTunes to be the easiest way to find new music and buy it. Consequently, most of my music is stored in .m4a files, which is an MPEG-4 container with AAC encoded audio.
So when I purchased a new Kenwood system for my truck, I was careful to choose a model that supports AAC files.
It turns out, that is not enough.
The Kenwood DPX502BT that I bought only supports AAC in .aac files. A file with a .aac extension evidently has no container. It is just the AAC-encoded audio. I found an online converter to convert a .m4a file to a .aac file, and the DPX502BT played it. However, it was missing the metadata (the title and artist). Why? Because that was stored in the MPEG-4 container.
I haven’t figured out what to do.
Convert all my iTunes library to MP3? It may come to that. Apple has instructions. Ugh. It creates a second item in my library for the converted file. That’s going to be a mess.