How to convert .mp3 to AAC?

I am using my Nokia C2-01 which does not accept mp3s. I am thinking how to convert my mp3s to aac because it should maintain the sound quality well. Another option is to convert mp3 to m4a but I think it is not so good because m4a is mostly a container. There is a lot of discussion about the reverse: convert from aac/m4a to mp3 but not relevant here. I did not find anything relevant in apt-get for aac. [Michael] I can do for one file ffmpeg -i test.mp3 test.aac but for many files the following does not work where the command is wrying to overwrite some .mp3 files for some reason. ffmpeg -i *.mp3 *.aac Output for a single file with ffmpeg --- Command ffmpeg -i test.mp3 test.aac takes a lot of time (50 seconds for 9 MB file) and takes a lot of space (9 #0:0 (mp2 (native) -> aac (native)) Press [q] to stop, [?] for help size= 25740kB time=00:49:26.67 bitrate= 71.1kbits/s speed=53.5x video:0kB audio:25303kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.725856% [aac @ 0x5619e57f44c0] Qavg: 375.695