Interlaced Field Dominance Confusion

[Ken Owen]

Thanks, David.

So going forward, would it make any sense to flag my clips as “progressive,” even if they’re not sourced that way? In other words, is there any benefit for playback quality?

I *really* appreciate your assist!

Ken

[David Roth weiss]

Negatory on that. Flag them progressive only if you want to mess up your otherwise good DVD.

David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los Angeles

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[Paul Dickin]

Hi
More explanation, from the ex-BBC guru:
“There is no specification of field order, as such, in any technical specification of video standards. The “field order” drops out of the specifications of the line/field scanning and frame blanking, which is all in ITU-R BT.470 and its successors (mirrored in the specifications by SMPTE and national broadcasting bodies). It’s all to do with the field blanking sequence, which specifies which line appears first in the video signal. That might be a whole-line or a half-line in analogue systems, so there’s no upper or lower field at all; that concept is overturned when you go to digital video, where the concept of the half-lines is dropped and all lines are full duration (e.g. 625 has 575 lines/frame of video, in two fields of 287.5 lines each, with a half line at the top of one field and a half-line at the bottom of the other). It is this extension of the half-lines that generates the concept of upper- and lower-fields, since the extra half line juts above the norm in one field and below it in the other.

Similar arguments go for 525 and for the interlaced 1080 structures.

And, if you do trawl all these specifications, you find that 625 is lower first, 525 and HD are both upper first. I can’t see how the standards can be interpreted otherwise.”
https://forums.dvdoctor.net/showpost.php?p=313002&postcount=22

(Note: The last comment refers to 486 line NTSC, not the later 480 line DV specification.)