Just a quick snipped to transform files from OGG format to MP3 format in *Unix based systems. Due to the command only accepts one file at a time, it needs a bit of bash shell code to make the trick and transforming all the files in a directory.
find . -type f -iname '*.ogg' -execdir sh -c \
'ffmpeg -v 8 -i "$1" "${1%.*}.mp3" && rm -- "$1" && echo "$1"' sh {} \;
Binary Coders 