Possible to reencode audio without reencoding entire video file?

[doofies]

Hi, I have a question, and I need some help.

I converted a DVD into an XviD file using Gordian Knot.

I however chose the wrong ac3 audio track to encode the audio.

My question is, is it possible to just somehow encode the audio into the video file, without having to re-encode the entire thing? If I could save an hour or two on the encoding, it will be very convenient, as I have almost 500GB worth of DVD's to encode. Well thanks in advance.

[steveryan]

You could use Avidemux -

Load your AVI file.
Hit the audio tab at the top of the screen.
Select main track/external AC3, click ok and load your AC3 file.
Make sure video and audio are set to copy then save.