What's going on?? 2nd half of chopped AVI is bigger than 1st half!

[Prizm]

What is this? I just did a 1400MB DivX 4 using Gordian Knot, and
the result was a 1.38GB file (with audio). Great, should fit on
two 700MB CDs, right?

Well, I fire up VirtualDubMP3 and select the first half of the
movie - the result is a 701MB AVI with length of 1:05:15. Cool.

Now, I select the second half of the movie and it comes out as:
713MB, length of 1:04:29. What is VirtualDub doing? The second
file is shorter in length and it comes out bigger!?

Can someone please enlighten me as to what's going on...I hate to
drop the audio from 160kbps to 128kbps for the sake of 13MB.

Is this some sort of overhead issue? Interleaving?

Prizm

[Zhnujm]

1.38GB * 1024 = 1413MB so your size (701+713=1414MB) comes very close. just cut a little later to make both files the same size.
the bitrate isnt constant over the movie so most times the second part wich more fast action scenes is bigger.