Question: I download lots of lectures from iTunes U. The problem is, they usually come with video and there is no audio-only version for many.

How can I, using any software available for Snow Leopard, free or paid, extract the audio from a series of video files and end up with a series of audio files?

Any ideas?

Answer: 
I suggest using [Max](http://sbooth.org/Max/) or [ffmpegx](http://www.ffmpegx.com/), which is a GUI for ffmpeg.

You can also use ffmpeg from the shell:

```
for f in *.mp4; do ffmpeg -i "$f" -vn -c copy "${f%mp4}m4a"; done

```

`-vn` (video none) removes video streams and `-c copy` disables re-encoding the audio. You can install ffmpeg with `brew install ffmpeg` after installing Homebrew.
Please try it with [VLC](http://www.videolan.org/), see [Extract Audio](http://wiki.videolan.org/Extract_audio) in the Videolan wiki.