FIELD TYPE - EXPLANATION ?

[Accolades]

Hi,

Could someone please explain the difference between:

FRAME BASED:

UPPER FIELD:

LOWER FIELD:

And why one should be set/changed when editing/creating DVD.

I am sure it means something...

Thanks

ps yes I searched - too many messages with the words FIELD and TYPE !! hence the question - maybe make a sticky ?

[Ken Berry]

Trying to put it very briefly and simply, normal interlaced video broadcasts two sets of lines which together ('interlaced') make up a single frame or image. Needless to say, the lines are broadcast very quickly so the eye cannot see anything except the final 'solid' or unified interlaced image.

Some systems broadcast line 1 first, followed by 3, 5, 7 etc up to (in PAL land for SD video 625), followed by 2, 4, 6, 8. That would be Upper Field First. Some systems use the opposite, broadcasting lines 2, 4, 6, 8 etc followed by 1, 3, 5 etc -- Lower Field First... It does not matter which one is used in terms of final quality, but one of the reasons there is a basic rule in video editing requiring you to maintain the proper Field Order is that if you get the order wrong, then the thing looks a little wrong and the eye can detect this.

Frame based is the broadcasting of a single image, rather than sets of alternating, interlaced lines. That is, with SD video, mostly tied up with still photos which come as a single frame in the first place. That is why slideshows are probably easiest done using Frame Based.

Things get a bit more complicated with high def video, but essentially it operates the same as above when dealing with 1080i (for interlaced) video, only there are more lines involved and more pixels, so the final quality of the image is higher.

But the highest quality of all comes from progressive or 'p' video (1080p or 720p) where all the lines are simply broadcast quickly but sequentially (1, 2, 3, 4, etc). This is not the same as, but similar in principle to Frame Based in SD video.

[Accolades]

Ahhhhhh, Clear as mud

Ok in good ol PAL land to KIS. When video editing and you have two videos, one in upper and one in lower what is the soloution?

Or you have combination of videos in Upper and lower and some still images?

When rendering is it essential to ensure you have the right order or is this using same as first clip option?


Thanks

[Ken Berry]

As I said above, the general rule is to maintain the same Field Order throughout a project. The corollary is that you should not mix the two types in one project. If you do, and you burn it using, say, UFF, then the LFF video in the project will come out wrong -- jagged edges on straight lines and when panning being the two most common defects. So I am afraid it is not simply a matter of chosing Same As First Clip, because those parts of the project which are *not* the Same As First Clip, will come out wrong...

Including photos makes no difference because while they are Frame Based, they can take on the aspect of either UFF or LFF with no problem.

You can, however, have two or more rendered videos, each with a different field order, burned to a DVD.

[Accolades]

Ahhhh...

So load,edit videos of same type/fields and create mp2 file(s) then when creating final DVD add the MP2 files created ?

or would the final DVD creation change field order?

[sjj1805]

Some tests were conducted some time ago and contrary to previous belief it was discovered that it is OK to mix field orders.
Please view Combining Upper & lower field

[Ken Berry]

I am still not convinced that you can, or should, do much more than mix two different, finalised mpeg-2s using different field orders on the same DVD. However, I continue to believe that it is not advisable to mix the two field orders in the one project. You might not notice much if there are no bold vertical lines or rapid panning.

But I guess the proof is in the pudding -- in other words you can only try it out and see for yourself. Me, I err on the side of caution...

[erdna]

Like I reported before, I did several tests w.r.t. field order with interlaced AVCHD video clips containing fast horizontal motion (where you normally can see field order artifacts very clearly) and I got no difference with UFF vs LFF. My conclusion was then that with interframe codecs (like the long GOP mpeg2 and 4 (e.g. HDV and AVCHD) it doesn't matter..the correct field order is automatically applied. Only e.g. DV, being an intraframe concept,(advanced MJPEG) needs an UFF/LFF setting. I would very much appreciate if some forum members could veryfy/contradict this experience. See also http://forum.videohelp.com/threads/2732 ... s-or-lower