How can I convert an .mp3 to .flac?

Can someone tell me how I can convert an .mp3 audio file to .flac format using ffmpeg? I Googled extensively, but almost all resources point to converting .flac to .mp3, in such a way:

ffmpeg -i "input.flac" -ab 320k -map_meta_data 0:0 "output.mp3"

Solution 1:

Did you try ffmpeg -i input.mp3 output.flac already?