VDub, Direct Stream Copy, but double frames?

[cradix]

I have an AVI (352x480, 48k audio) that I captured in VDub. Windows reports this file to be 5,916,725,248 bytes. I can encode the file no probs in TMPGEnc. It says it is processing XXX out of 43198 frames and says it's going to take about 45 mins to finish.

Now, I take that SAME file and do a Direct Stream Copy for BOTH audio and video and resave the file under a different file name. I now have a file that Windows reports to be 5,917,347,840 bytes (608k bigger).

The problem is, though, when I take that second AVI (which *should* be a fairly identical file to the original) and load it into TMPGEnc with the exact same settings as before, it tells me that it is processing XXX out of 86148 frames and says it's going to take 1.5 hrs (twice as long) to finish! WHY?

Why does it think it needs to encode twice as many frames as it really does? Vdub is set to direct stream copy on both audio and video, so what am I missing?

Thanks. --Matt

[cradix]

nobody has any ideas?