Pedantic NTSC field order question

[remsleep]

Yes, I understand fields, frames, pulldown, etc, and I could do experiments to answer most of these Q's (although the ones about the TV itself not so easily), but if someone could clear this up for me once and for all, it would help alot.... (at the very end, I explain my reading of the guides)

All the terminology is ambiguous in a way -- I hate to be pedantic, but...

Q1: When someone says "top" field does this mean:

(a) it is the field that contains scanlines 0,2,4,6,... regardless of whether it is appearing 1st or 2nd in, say, a field-based MPEG2 file [NOTE: I'm using "scanlines" in the 720x480 sense, not the true physical 525 NTSC scanlines, which is the opposite parity from 480....]

(b) it is always the first (or second?) field for this frame appearing in the file, and may actually contain the even or the odd scanlines.

Q2: Does this world start counting from 0 or from 1? If the fields are: 1a 1b 2a 2b 3a 3b 4a 4b... Are the a's the "even-numbered" fields or the "odd-numbered fields"? Or again, when people say these terms, does it acutally depend upon whether the fields have the even/odd scanlines?

Q3: OK, say I have an NTSC non-progressive DVD, so it has some field order. In the first 1/60 of a second it gives whatever is the dominant field to my TV -- does my TV (pretending again that it has 480 scanlines) put this field on scanlines 0,2,4,... or on scanlines 1,3,5... I'm assuming that there's no way dominance is communicated to the TV -- a TV must have some native order, and the DVD player just feeds it appropriately based upon the dominance indicated in the mpeg2...


Q4: OK, almost most there (I guess this is actually a variant of Q2). If I have some known-to-be frame-based avi, and in AVS I did something such as:

AssumeTFF
SeparateFields
SelectEvery(8, a,b, c,d, e,f, g,h, i,j)
Weave

(a-j are taken from [0..7] in some pattern, of course)

Is field 'a' a 'top' field? (note I started TFF to establish a particular parity for this example)

Is field 'a' an even or an odd field?

If I run an upper-field dominant MPEG2 encode (I'm assuming 'upper', the Adobe lingo, is synonymous with 'top'), and author the DVD, and then cast a time-stop spell 1/60sec into my playback, will I be seeing field 'a' or field 'b' on my TV?

--

Many thanx to the guru who can clear this up...

The guides give the even/odd example which is perfectly fine for the concepts of telecining, pullup, etc.. and the guide has the nice diagram:

EVEN a a b c d
ODD a b c c d

But what I still think is not clear: Which (of the 480) scanlines are in field 'EVEN a', or does it depend? Also, I still have Q1 after reading this section in the guide -- is the first 'EVEN a' field an even field because it is the first to appear in time when viewing, or because it has even scanlines. In other words is

ODD a a b c d
EVEN a b c c d

Also a possibilty, if the dominance were reversed, with the first field to be displayed time-wise, being 'odd', presumably becuase it contains odd-numbered scanlines? But then is it a 'top' field?

Anyway, I'll stop here...

[AbsoluteDestiny]

It doesn't actually *matter* whether odd is top. The numbering of the lines is arbitrary.

All you need to know is that the "top" field is the very top line and every other alternating line from that and the "bottom" field is the 2nd line from the top and every other line from that.

[Vlad G Pohnert]

I agree with AD.. Don't make it more complex then it already is

Vlad

[remsleep]

Thanx - the motivation is that I'm essentially pulling up footage myself with Weave() to make a DVD to watch with my friends on television. When I let the Adobe Media Encoder do its own transcode, the quality wasnt the greatest, so I figured I would AVS exactly what I want.

But, since I can only see complete frames, and not which field is going to appear first, I dont know if my weaving pattern is good or not.. Moreover, Adobe defaults to "lower" field in the encode, but I dont know which one that is, nor do I know which order the TV is going to display them... Naturally, I got it wrong (ouch painful to watch, as you know). But simply changing to "upper" field in the encode doesnt always seem to just work...

However, I can now use what you have given me -- If the top field is the top (of my 480) scanlines, I just need to, for instance, inspect my combed frames and confirm that 0,2,4.. are from the previous frame, and 1,3,5.. are from the upcoming frame, set the AVS dominance to TFF, and tell Adobe to encode "upper" field first...

As a workaround, I've just encoding progressive and my friends TV can even be set to "progressive", so this is certainly better than a bad interleave, but it is not as smooth as it could be by just getting the interleaving correct, and moreover MPEG2 then has to deal with the combed frames which is quite sub-optimal...

BTW, since I have the experts' attention.. The TV also has a setting called "cinemotion" (eg, interlaced, progressive, "cinemotion") -- do you guys know what that could possibly be?

--Thanx again!