Field or Progressive?

[BKM]

Did a little google and found this about Avid DS.

The DS preset is telling you the FIELD DOMINANCE of the DS, not the FIELD ORDER. See below.


NTSC - from the DS Editing Guide
Field 1 (upper) contains ODD lines
Field 2 (lower) contains EVEN lines

720 x 486 NTSC - FIELD ORDER of lower field, F2, first

1st field in field order 2nd field in field order
lower, F2, even line numbers [2,486] upper, F1, odd line numbers [1,485]

The first field in the NTSC field order is the lower field, field number 2, containing all EVEN numbered scan lines.
The first picture scan line (line 1) is contained in the UPPER field - which corresponds back to NTSC FIELD 1. Therefore, DS sets its FIELD DOMINANCE to ODD (1 = ODD).

Also this may be a reason...

A LTC codeword is one video frame time long. As specified in ANSI/SMPTE 12M-1986, the start of a LTC codeword always coincides with a certain line near the beginning of an F1 field, regardless of the field dominance of the video material.

A VITC codeword (also defined in 12M) tags along with each video field. The VITC codeword has a "Field Mark" bit which specifies if the field is F1 or F2. A VITC codeword's hh:mm:ss:ff value always increments at a transition from F2 to F1, regardless of the field dominance of the video material.

So if your material is F1 dominant, then LTC and VITC behave as you would expect:


field type F1 F2 F1 F2 F1 F2 F1 F2 F1 F2
edits on tape E F G
LTC on tape 01:00:00:00 01:00:00:01 01:00:00:02 01:00:00:03 01:00:00:04
VITC on tape F1 F2 F1 F2 F1 F2 F1 F2 F1 F2
01:00:00:00 01:00:00:01 01:00:00:02 01:00:00:03 01:00:00:04

But if your material is F2 dominant, then LTC and VITC straddle your edit points like this:


field type F1 F2 F1 F2 F1 F2 F1 F2 F1 F2
edits on tape ... H I J ...
LTC on tape 01:00:00:00 01:00:00:01 01:00:00:02 01:00:00:03 01:00:00:04
VITC on tape F1 F2 F1 F2 F1 F2 F1 F2 F1 F2
01:00:00:00 01:00:00:01 01:00:00:02 01:00:00:03 01:00:00:04

This means that one frame of F2 dominant material consists of two fields with different timecodes!

See http://www.lurkertech.com/lg/dominance.html for more info and better pics.

BKM

[loops]

Hmm, yes, NTSC distinguishes between first/second fields and F1/F2 like that, ew. But even so, since the Reverse Dominance Tool changes the scan mode you'd think that PAL would have one and NTSC would have the other, yeah? But both default resolutions are F1.

I'm totally confused now :?

[rohit]

i guess this is why PAL was developed

[imported_johnmont]

100% of our work in NTSC is at the default -- Field 1.

That being said, I still use the old school method and set up my project for progressive.

[Smith12895]

100% of our work in NTSC is at the default -- Field 1.

That being said, I still use the old school method and set up my project for progressive.

Glad I'm not alone!



and thanks everyone for all your insight! Jeff your link to that tip answered many of my questions. Thanks again!