files expand

[agent222]

I've used VirtualDub, and, VirtualDubMod, to join .avi files together. But lately I've encountered something with VirtualDub that's made it unusable to me.
For instamce, I had two .avi files that when together were just over 4GB. But when I tired to join them with VirtualDub, it expanded the videdo files to over 50GB. This has happened a couple times, and, I don't understand why it's happening. I thought I understood that VirtualDub took the files and just merged them seamslessly, (providing that everything matched in the files to be joined.) So why is it expanding the video files in the merged product?
Thanks to any who can help, and/or, explain.

[Baldrick]

did you select video->direct stream copy?

[agent222]

Baldrick the Wise;

AHA! In (re)selecting that option, it did solve the problem. I think in trying work with another format. using the auxillary extensions for VirtualDub, I'd changed that. Resetting it not only stopped it from expanding the file size, but made the joining process "infintly" quicker as well.

This is just the reason for belong to these forums. You can normally find out what you're doing wrong very quickly.

Thank you very much, o wise one.

[ZippyP.]

FYI, If you don't select "Direct Stream copy" for both audio and video, and you don't specify a compression type, then Vdub will save it as uncompressed.