AC3 conversion?

[coppit]

First, thanks for USM. It's great!

Question: I have an AVI with AC3 audio. On my iPhone the video plays without sound. I'd like to transcode the video so that I can hear the audio. How do I set that up?

Also, once I have that working, if I specify "avi" in the forced transcode extensions, does that mean that even if I select the file normally (not in the transcode virtual folder) that it will transcode using the preferred video file engine?

Thanks!