That would seem bizarre, but I'm not sure what else could have happened.

I recently upgraded to Ubuntu 12.04, did a fresh install, then moved files from a backup hd. There are a couple albums, ripped before the upgrade, that I hadn't moved to my phone (Motorola Android), so I plugged in the phone (USB) and fired up Rhythmbox as usual.

Rhythmbox took a long time to read the phone/card, but once that was done, I copied the two albums as I'd done before for many files in 10.04 (drag & drop). It seemed to be fine, but once I tried to play the music from the phone, the player app informed me that it couldn't play files with that format. I checked the file info, and apparently the phone files are m4a -- though on the computer, they are still ogg.

What's more, all the music files that I'd previously moved to the phone's SD card are also now m4a, including albums that I was able to play just a few days before, as well as files that were originally mp3 (instead of ogg).

The whole thing makes little sense to me -- I have no idea why either Rhythmbox (or Android) would batch convert files to m4a. Any help on why this could be happening would be appreciated. FWIW, I haven't added a lot of multimedia programs, although I did install the "restricted-extras" package. Thanks!