Upper field/lower field - when orders are opposing

entilza72 wrote on 5/9/2010, 2:34 AM
Hi gang,

Looking to see if someone has a real quick off the cuff answer for this:

I know what happens when you import video into Vegas (or any other NLE) with the wrong field order - you get a stuttering effect. Understandable.

However, I am working on a project that contains mostly upper field first video.

The output is for PAL DVD, which is lower field first.

So I am leaving the material as upper, and the Vegas project (and render-as settings) are set to lower.

Works fine.

However, on the output field I have noticed some "progressive" style pans and some wides look rather "low res" - just like a pal interlaced image has been converted to progressive by using a single field only. To me, this suggests that perhaps Vegas has no option other than to hold a field for 2 fields, just like progressive, as the source is in the wrong order for the target and there is no "clean" way to convert it.

Can anyone confirm if I am right?

And if I am right, can PAL DVD handle upper first? Or am I stuck with lower?

Cheers,
Jason

Comments

farss wrote on 5/9/2010, 6:16 AM
First of please please, please read ALL of this thread:

http://www.sonycreativesoftware.com/forums/ShowMessage.asp?MessageID=671694

Its long and gets a bit messy but is a goldmine of information.


Bob.
entilza72 wrote on 5/9/2010, 6:18 AM
Perhaps an answer to my question:

I have seen someone state that PAL and NTSC DVDs have no required field order, and simply impose the field order as written in the file's header (specifically here: http://nickyguides.digital-digest.com/interlace.htm under the title "DVD & TELECINE").

I'm a little wary of that statement, however. (Maybe its because I couldn't help noticing that every PAL & NTSC template in Vegas is lower field first.)

Can anyone state if the "any field order is OK" statement from that website is correct, or incorrect? If it is correct, my problem is solved. If it is incorrect, it means a PAL DVD must be lower field first, and therefore answers my question. Win win. :-)

Cheers,
Jason
Former user wrote on 5/9/2010, 8:15 AM
Maybe to clarify.

The field order is not important, but it needs to be consistent. You cannot easily mix files of different field orders.

The DVD (mpeg file) needs to be the same field order as the original source.

Dave T1
musicvid10 wrote on 5/9/2010, 8:34 AM
For DVD, the field order can be either, but must be consistent as Dave suggested.

Actually, you can take UFF source video and render LFF MPEG-2 for DVD with no problems in Vegas. I often do this quite often when using VRO (UFF) with DV-AVI (always LFF) in the same project.
TheHappyFriar wrote on 5/9/2010, 10:11 AM
I can also confirm that as long as the field order is consistent in the mpeg you're good. You can however, w/o issue, have DIFFERENT field order mpeg's in the same DVD.

Your biggest issue with Pal & NTSC on the same DVD will be a) the framerate & b) the different heights. even though both can be the same field order PAL has more lines then NTSC so to match you'd need to play with it a bit.
entilza72 wrote on 5/9/2010, 2:14 PM
Hi all - thankyou very much. This is *exactly* the info I was hoping for. Bob, I'll get cracking on reading that thread straight away.

You know, I spent at least an hour googling field order info, and the best I turned up was that link I didn't trust that said DVD can be any order. I should have known the answer would be hidden in these forums somewhere!!

Thanks again,
Jason.
TheHappyFriar wrote on 5/9/2010, 6:15 PM
when in doubt: render a test DVDRW. :)
entilza72 wrote on 5/9/2010, 8:41 PM
Hi all,

Just to confirm my findings:

My project has progressive and PAL Upper Field First (UFF) sources. There is no need to switch orders during the edit.

I was previously under the belief that PAL DVD (my target format) *required* Lower Field First. This belief is incorrect. It would appear DVD uses which ever field order you render as.

So my solution is simple: Output as UFF, keeping the output field order the same as the asset/content order.

Thanks again for everyone confirming DVD can take any order.

Jason.
musicvid10 wrote on 5/9/2010, 8:49 PM
I can confirm your findings using another source.

DVD-RAM (VRO) files are UFF. That is the only difference from VOB files, which are generally LFF.

Rendering the VRO files to either Upper or Lower DVD produces a perfectly playable disc.
TheHappyFriar wrote on 5/10/2010, 5:40 AM
analog recorded mpeg's & DVD's recorded on a camera seem to be backwards too.

I just had a major issue with that.

What I don't understand is why they'd record those source backwards when it's (technically" wrong. If they didn't things would be sooooo much simpler on my end!
Former user wrote on 5/10/2010, 5:50 AM
There is no specific standard for field order. Most uncompressed sources are UFF. MJPEG which was one of the first home type codecs was UFF. LFF was introduced with DV AVIs. If you check most commercial DVDs are UFF. Neither is technically wrong or right.

Dave T2
farss wrote on 5/10/2010, 7:04 AM
I find the term "field order" thoroughly misleading. Its very rare and next to impossible to get the fields in the wrong order and when it does happen the outcome is diabolically bad. Imagine if you somehow got the frames in the wrong order. It took me ages to get the basic idea right.
UFF means the first field (1) contains odd numbered lines i.e. 1,3,5 etc. The next field (s) contains even numbered lines i.e. 2,4,6.

Getting the field order wrong does not mean that the order in which the fields are displayed has become 2,1,4,3,6,5! It does mean that fields are still displayed in the correct order however the lines in the first field and the second field are in the wrong order down the screen i.e. the lines in the first field are being displayed as lines 2,4,6 and the second as 1,3,5.
This has a faily subtle impact. The vertical res of interlaced video is only a bit above above half the full frame so a static shot doesn't look much different, I've never picked field order as being wrong from this aspect. Where its visually obvious is in vertical motion, not horizontal. If somehow the field sequence is switched then any motion is obviously mangled.

Bob.