I have some mp3 files - stems from a track ready for remix. The originals in a non-lossy format are not available. I would like to open them in Ardour, on linux, but Ardour doesn't open mp3s, because of licensing problems. I would like to convert to an open format, with no data loss, and with file sizes as small as possible (I know converting from mp3 to a lossless format doesn't gain me any quality. I just don't want to lose any more quality). I was thinking that flac would be the obvious solution, but am open to other suggestions.
Suggestions for other OSs are welcome too, as long as the result is an open format.
Clarification: it'd be nice to be able to maintain meta-data too.