would like a discussion on field order issues

[jdefed]

Does a captured AVI file have a field order? What programs can check this? I thought Gspot did, but I loaded a file and it didn't show it. While seaching for answers I found that some capture devices reverse field order, is there a list somewhere that list these devices? I'm using an OEM capture card with fusion 878 chip with BTWINCAP driver, does this reverse order? When converting to MPEG2 for DVD is it always field order A first? (I think different programs use different terms like Top order or Bottom order.)
Any other information on field order would be appriciated.

[communist]

I'm only going to comment on the things I know for certain (more or less).
Yes some capture cards reverse field order but that can be taken care of when processing the captured material.

For DVD field order has to be specified. It can be Top or Bottom field first. From what I've read Top Field First is used most times except for DV where it is always BFF (the actual material has that field order - not the encoded DVDs). As long as you tell the encoder what you're feeding it / set it up properly it should produce 100% spec compliant streams.

Also you should refer to TFF or BFF because that specifically says which lines are meant - whereas A or B dont have a real meaning to people who dont know this naming convention. Also used is Upper (=TFF) and Lower (=LFF) field first.

To find out what field order your material has pick a scene with motion, create an AviSynth script like this:

AviSource("yourfile.avi")
Assume*FF # try with T and B
SeparateFields()

Whichever combination (TFF or BFF) give you smooth motion is the correct field order of your material. The wrong field order should give you jerky motion (forward -> backward -> forward -> backward etc...).

[jdefed]

The reason i used A & B was the program I started on was Ulead Videostudio7 and thats the term they use. I assumed that A was TFF but I discovered yesterday on uleads forum B=TFF so that may be part of my problem.(One of many that I have had during my several years of this enjoyable endeaver.HAHA) I probably should try AviSynth not sure if I'm that proficant in that part of the computer world.