mpg with ac3

[bigH]

I'm taking captured betamax video and making mpgs (video transport streams).

I'm using Storm Edit/Video and Premiere. The resulting mpg has good video but no sound. I was told that I need to get the audio to ac3 for it to play on the server.
How do I create an ac3 file from the avi audio. Can I do it in Premiere or do I need a seperate app?
A tech at Manzanita said I can mux the ac3 with the m2v and get a synched mpg.

thanks
h

[setarip]

"do I need a seperate app?"

Sonic Foundry's SoftEncode can accomplish this...