If you install ffmpeg on your Mac using macports, you’ll discover that some very important audio and video codecs are missing. Consequently, you can’t transcode to some favourite formats like mp3.
There’s a very easy fix:
sudo port install ffmpeg +gpl +lame +x264 +xvid
That’s it. 🙂
If, in use, ffmpeg throws an error concerning a buffer size that’s too small, ignore it. If you look, you’ll see that the file got transcoded anyway.