Is there a good command line tool for converting to and from FLAC audio format?

Question

Ideally, I want to convert from MP3 to FLAC and back. I also need to be able to script this.

Answer 1

The fundamental tool for sound format conversions and simple transformations is SoX, the Swiss Army knife of sound processing programs.

sox foo.mp3 foo.flag

If you're running Debian, support for writing MP3 in sox is broken in lenny and squeeze (and as far as I know the same problem affects Ubuntu 10.04 and 10.10). This bug was fixed in early March 2011, so grabbing the latest source (or grabbing a binary for sox 14.3.1-1build1 or newer) and recompiling it should work.

An alternative for encoding to MP3 is lame. It doesn't read flac, but you can use sox or flac to produce a wav file, then lame.

flac -d -o foo.wav foo.flac &&
lame foo.wav foo.mp3 &&
rm foo.wav

Answer 2

sox version 13 and up supports FLAC, along with many other formats. sox can do many things to an audio file, not just convert from one format to another. It is to audio what ImageMagick is to graphics.

Answer 3

It's called flac, oddly enough. It's somewhat painful to use, or was back when I scripted a transcoding job with it.