I have a surround recording - 3 channels front, 2 channels rear - that I want to encode to ac3 for DVDA. Vegas's surround mixer seems simply to derive its own center channel. Is there a way to defeat this and replace the content with my actual center channel recording and then encode it?
Clicking on the speaker pictures in the surrond panner mutes the audio sent to that bus, so if you mute the FL, FR, SL, SR speakers on the track, you are left with just a send to C.
On the L+R track, turn off the Centre speaker (or pull down the Centre volume slider)