So I've had a need lately to convert MOV audio files to MP3. At first I searched for self contained solutions online and everything looked and worked like cr*p. So here's what I came up with...use VLC, then I put it in a powershell script.

Here's the commandline for VLC to do the work:

vlc -I dummy <INPUTFILE> ":sout=#transcode{acodec=mp3,ab=128,channels=6}:standard{access=file,mux=asf,dst=<OUTPUTFILE>}" vlc://quit

Then I just wrapped this around a "gci" on an input folder and viola! a script to convert a folder of MOV files to MP3

I've posted the full powershell script on the PoshCode site here: Convert-ToMP3.ps1