Extra frame in log file?

[Kalicrys]

After my second pass through,
I try to open the stuff in EKG.
And it tells me the log and video have different frames.
Huh?
I check the log file and it says that there are 80920 frames.
But my source only had 80919 frames.
Huh?
Where'd that extra frame come from?
Can anyone enlighten me?

It can't be the post processing, I only deinterlaced it(to the same frame rate), smoothed it and adjusted the color range using avisynth.
(I've been using 5.1 lately btw)

I've been tinkering, and I just realized that I'm getting an extra frame in the log file whenever I give it input with an odd number of frames.(though the output has the correct number)

[Kalicrys]

examining the last few few log entries, I came up with an hypothesis:
the extra frame is added to keep the PB sequence of frames.
however, this leads to another question:
if the extra frame (frame#80919) is not included in the output avi,
how does frame#80918 (the actual last frame) work as a B frame?

80903 I
80904 I
80905 P
80907 P
80906 B
80909 P
80908 B
80911 P
80910 B
80913 P
80912 B
80915 P
80914 B
80917 P
80916 B
80919 P
80918 B

my next test: going to edit the number of frames specified at the beginning of the log file and put it through another pass, and see how the encoder responds.

[Kalicrys]

results:
the encoder did not complain.
the resulting output after the second pass is 6114 bytes smaller, though it has the correct number of frames.