Ok here goes, i'll explain this the best i can.

I captured some cartoons (Bob and Margaret they are called), i captured them with xvid max CBR 640x480. I then i used vdub to cut out the adverts and end credits making each show 20 minutes long give or take a few seconds, then i compressed them with xvid through vdub again with xvid 1 pass quantizer on a setting of 5 (or so i thought) turning each show out at 100 megs or thereabouts, i captured and compressed the first 6 shows in that way, now when i try the same thing i have to use a quality setting of 9 or 10 on the quantizer to get the same filesize, or maybe i am just going a bit crazy and imagined i compressed the first 6 at quality setting 5, i dunno.

Any ideas what may have happened if anything at all happened, or am i imagining this?

I have set the defaults on xvid and started rom scratch, also reinstalled my o/s,.

Cheers.