That is what you should not be seeing. If you see that, then you have the wrong setting. Don't use 3 or 4 for that segment.
As to your capture and the settings. The reason you are having a problem is because the raw capture frame itself doesn't need IVTC. If the raw frame looks like 3 or 4, then it needs IVTCing. That's the kind of frame you should be referring back to to check your IVTC setting.
Also, you are losing enough frames to start creating an audio sync problem, and that's a bad thing. PM me your e-mail, and I'll send you the program I use. We'll lick this thing yet.
"the screenshots all look very similar except for offsets 3 and 4 which had obvious scan lines and seemed to be introducing parts of the surrounding frames"
That is what you should not be seeing. If you see that, then you have the wrong setting. Don't use 3 or 4 for that segment.
As to your capture and the settings. The reason you are having a problem is because the raw capture frame itself doesn't need IVTC. If the raw frame looks like 3 or 4, then it needs IVTCing. That's the kind of frame you should be referring back to to check your IVTC setting.
Also, you are losing enough frames to start creating an audio sync problem, and that's a bad thing. PM me your e-mail, and I'll send you the program I use. We'll lick this thing yet.
BTW, I found this forum and this faq (since I don't personally know your hardware.) You might want to peruse through them.
http://www.pixelmagicforum.com/forum/forumdisplay.php?f=7&page=2&sort=lastpost&order=&pp=25&daysprune=-1
http://www.pluggedin.tv/sweetspot/support/faq.html#5d
BTW, just out of curiosity, are you in NTSC-land or PAL-land?