Hi,
I have just started to use Vegas Pro 8.0 for AVCHD rendering (because the crash of Sony Vegas Movie Studio Platinum 9b) 1920 x 1080, 50i 5.1 Pal. I found out, that AC-3 is missing from Vegas Pro 8.0. Why???
Your original message said you were using Vegas Pro 8 and this is the Vegas Pro forum so the answer I gave you was based on the assumption that you were indeed using Vegas Pro 8.
Now you say you are using "Studio Pro 8". I am not aware of any Sony product of that name, but I suspect that you are really using some version of Vegas Movie Studio 8, possibly VMS 8 Platinum Pro Pack. If so you will be more likely to get the answer to your question in the Vegas Movie Studio forum, which is where the people who are conversant with the various Studio versions mostly hang out.
Most of us in the Pro forums are quite happy to answer your questions, but we are not always up to speed on the things that are missing and/or different between the Pro version and the Studio versions, so the answers you get here may sometimes not be applicable to your (VMS) situation. This may be one of those occasions.
The history is that. I used first Vegas Movie Studio Platinum 9, but You konow, that the rendering of 1920 x 1080-50i Pal 5.1 crashed and no solution has came out. Therefore Sony Creative gave to me Vegas Pro 8 but I did not get any suitable DVDA for Pro8. I think, that therefore AC-3 is missing. I don´t understand their policy!