Upper or Lower field order..please help

[Fotis_Greece]

Could someone please explain what is this Upper or Lower field order in video files. Does this have to do with Pal or NTSC formats? When capturing from my mini dv camcorder into my computer the file is in Lower field. So when rendering to mpeg2 DVD pal should I use this setting, lower field?

[bb]

You have field based video if it is interlaced. Most DV files are interlaced, because there are not many camcorders providing progressive scan.

And yes, you should set the field dominance to "bottom field first" when encoding to DVD MPEG-2. Else you'd get a weird up-and-down jumping picture. But I recommend you test it with the wrong setting on purpose, so that you know the effect (and can tell your friend if he's got the same problem).

bb

[Fotis_Greece]

Thanks for your answer. Can you please tell me then why most (not to say all) DVD movies are in Top (upper field first)? I have checked 9 dvd discs (hollywood movies) with Bitrate Viewer and they're all Top Field first

[bb]

I'd say simply because they're produced like that. In fact most Hollywood movies are progressive material, but if encoded interlaced, they are probably phase shifted with top field first.

Don't worry about that. The tff/bff flag just tells the decoder where to "draw" the first field: starting from the first line or from the second. Then every other line is skipped (interlacing), and the next field is displayed vice versa. There's no quality difference just because of the source having a dominance of top field first or bottom field first. But you need to set it correctly, because otherwise the video will "jump" up and down.

bb

[SomeJoe]

Originally posted by bb
The tff/bff flag just tells the decoder where to "draw" the first field: starting from the first line or from the second.

I'm not sure this is correct. What you're describing here is that the TFF flag would shift the spatial order of the fields. I don't think it does that, it changes the temporal order of the fields.

In other words, the data in the first part of the frame in the file is always drawn starting on line 1, and the data in the second part of the frame in the file is always drawn starting on line 2. The TFF flag just controls which is drawn before the other.

TFF=0 (bottom field first): Draw bottom field starting on line 2 first, then draw top field starting on line 1.

TFF=1 (top field fiest): Draw top field starting on line 1 first, then draw bottom field starting on line 2.

[bb]

@SomeJoe:
Yes, my post was misleading, so thanks for clearing up. I did not intend to say the spatial order would be changed, but the temporal order of fields like you described. Anyway, in one case the first line is drawn first, in the other case the second.

If you need to change the spacial order indeed, you may appreciate a new filter which has been developed recently:
http://forum.doom9.org/showthread.php?s=&threadid=46765

bb