How come the Disc Space Used counter at the bottom right of my BD project in DVDA shows only 21.3 GB, but the project errors as Project too large for selected media (25GB BD-R). It renders and prepares into a 31GB iso file I notice. The project properties show it also as 21.3GB or 25GB used.
You have to prepare your appropriate audio and video separate streams from VegasPro - the combined sums of their file size -minus a little is what you are aiming for. I disregard the estimate counter with DVDAPro because it is not going to be a "good" estimate given that you may be coming close to the margin of error.