patrick@patrick-desktop:~$ mencoder audiodump.wav -o for_us.mp3 -oac mp3lame -ovc copy
MEncoder 1.0pre8-4.0.3 (C) 2000-2006 MPlayer Team
CPU: AMD Athlon(tm) 64 Processor 3500+ (Family: 15, Model: 15, Stepping: 0)
CPUflags: Type: 15 MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 3DNow 3DNowEx SSE SSE2


WARNING: OUTPUT FILE FORMAT IS _AVI_. See -of help.
success: format: 0  data: 0x0 - 0x23a802c
Audio file file format detected.
Video stream is mandatory!

Exiting...