Finished file is too small ???

[ps2uk]

hi guys im encoding a film that is 2 hours 6 mins i worked out the file size & bitrate for 2 cd's but with the latest xvid codec the finished file is coming out too small.have i got some setting wrong it worked fine with other builds.
i tell the calculator a finished size of 1397mb with audio and it is coming out about 200mb smaller than the size i tell it
also what is a good bitrate calculator to use

codec used - XviD-1.0.1-05062004
bitrate calc used - nitrogen bitrate calculator 1.20

settings used
vbr mp3 audio 104mb
movie size 1397mb
video size 1319929
video bitrate 1430

AS @ L5
2pass
6-ultra high
1-mode decision
use chroma yes
turbo yes
quantization type MPEG
quarter pixel yes
quantizer
2
31
2
31
2
31

thanks in advance :)

[Asmodian]

You should use search, this is one of the most commonly asked questions.

Your movie was too compressible, it used quant 2 then entire time and it was 200Mb smaller then you asked. There are many ways you can get a larger file, some result in better quality while other just waste bits with little gain in quality.

I think using a larger resolution (but not above the source res, of course) or a high bit rate custom matrix are the best options. You could also turn off B-frames (or set them to a ratio of 1 and offset of 0) if you have them on or set the min quants to 1 and the rate control to 20-20-20.

[ps2uk]

sorted the prob now i was the quants :)

thx guys

[Sharktooth]

Undersize and oversize are the most frequent issues with encoders.
If you use search you will find there are plenty of solutions from using a custom quantization matrix, setting different quantizer min/max values to tweaking other settings...