TmpGenc: same bitrate, different file sizes ??

[jimA]

I have this clip.

Using TMPG (I tried different versions, including Xpress 3.0).

Using FitCD I find out that I should use a bitrate of 2345 to make the filesize 793mb.

using Xpress3.0:
Encoding with CBR I get a filesize of 793MB.
Encoding with vbr, quality High, file size=775
Encoding with vbr, quality Low, file size=781

WTF !!!

/jima