converting aac to mp3

cd /home/user/Downloads/iplayer
get_iplayer --get 10457 10458 10459 10460 10461 --force
for i in *.aac; do
    ffmpeg -i "$i" -ac 2 -ab 128 "${i%aac}mp3";
    mv "$i" "aac/";
    mv "${i%aac}mp3" "mp3/";
done