Forgot to mux AC3, cant find the button in Vdub

I might begin by admitting my total ineptitude. After forgetting to add "mux ac3" to the queue for star trek5 you'd think i'd have learned. I did. all other eight DVDs i backed up with full ac3 sound nicely muxed. all in russian. thank god for large RAID volumes and an inherent inability to part with anything. even junk. I've tossed out the muxed avis bt kept the sound-less ones, and since i also kept the vobs on my drive i easily demuxed the ac3 streams from that. so i now have 9 avis with no sound and i cant find out how to mux the sound from within vdub without re-encoding the whole movie. with only one PC this is not happening if there's an alternative :( I'm sorry if this seems REAL moronic, but I just can't find it and there's no reference to idiots like me doing dumb stuff like this in the vdub guide, the audio guide, or this forum.

You can easily mux (and split, if necessary) it with .

...and the real reason you can't find the AC3 sound option in VirtualDub is that it is only available in NanDub... So, open the soundless AVI in NanDub (File->Open). Then open the .AC3 file with Sound->AC3. Then set both Video and Audio to 'Direct Stream Copy' (Audio should have this as default). Set Audio->Interleaving to 64ms and 64ms preload. Also set delay according to DVD2AVI or smartrippers calculations. Then finally save the AVI as a new name. Won't take more than a few minutes.

thank you both.