RE: field dominance fun..?

[AGreenberg(at)chaines.astral.com]

I don`t want to start a whole topic on this 2 month old thread, but for the people who are unsure, the field domininance setting in the DS does not only refer to which field the edit occurs, but actually the field order. ( In fact, I dont`t even know if it refers to the video edit at all, but I assume it does ) If you output to file some interlaced footage and capture with field domininace set to odd and then capture again set to even, they will not give you the same result. One has the field order reversed giving an ugly unprofessional result which I am sure we all have seen somewhere at some time on some tape and thought ``What`s up with that mess ???`` So although field order and field domininace may be 2 different things, they are the same thing in the DS. In fact with version 7.6, it seems like you could referse the field order on output, but upon investigation, it seems importing that with any setting does not give the correct result. You either get the wrong field order, or you get the correct field order but a soft result.

 

-----Message d'origine-----
De : owner-ds(at)Softimage.COM [mailto:davet(at)edgeworx.com]
Envoyé : 10 octobre, 2005 11:09
À : DS(at)Softimage.COM
Objet : Re: field dominance fun..?

 

The biggest misunderstanding comes from whether you start counting from 0

(like a computer programmer), or 1 (like almost everyone else).

 

Field Dominance is where in time the video edit occurs: either at the

timecode given, or 1/50th or 1/59.94th of a second later.

 

Field Order is the spatial position of each field. Upper means that F1 gets

the 1st scanline or raster. Lower means it gets the 2nd scanline.

 

Today there's a strong correlation between TV standard and Field Order, but

that didn't used to be the case. I seem to remember NuBus Avids and Radius

Videovision used to be Upper Field, and Intelligent Resources' Video

Explorer was Lower Field, both for NTSC.

 

-DaveT

 

 

 

On 10/10/05 3:40 PM, "jamie dickinson" <dickij10(at)hotmail.com> wrote:

 

>

> I'm determined to nail this! I'm looking at this;

>

> http://www.lurkertech.com/lg/dominance.html

> ... which is making some of it clearer.

>

> cheers

>

>> From: "Ryan Collier" <rcollier(at)postcentral.com>

>> Reply-To: DS(at)Softimage.COM

>> To: <DS(at)Softimage.COM>

>> Subject: RE: field dominance fun..?

>> Date: Mon, 10 Oct 2005 09:51:29 -0400

>>

>> Well, I could be 100% wrong -- ha!!

>>

>> My personal experience with PAL is somewhat limited.

>>

>> But, this is how I've come to understand it from a variety of sources. Most

>> of which came from the American Cinematographer Video Manual (a highly

>> recommended purchase, along with the Film Manual) as well as Chris & Trish

>> Meyer's Creating Motion with After Effects (also a recommended purchase).

>>

>> Both are excellent resources.

>>

>> Cheers,

>>

>> Ryan Collier

>> Avid|DS Artist

>>

>> --------------------

>> The Past is Prologue

>> --------------------

>>

>> -----Original Message-----

>> From: owner-ds(at)Softimage.COM [mailto:owner-ds(at)Softimage.COM] On Behalf Of

>> jamie dickinson

>> Sent: Monday, October 10, 2005 9:27 AM

>> To: DS(at)Softimage.COM

>> Subject: Re: field dominance fun..?

>>

>>

>> Ryan

>> Thanks. I keep thinking I've got it now... but ... I need to digest this.

>> This sometimes seems contradictory to what I thought I knew. I keep going

>> back to the simple scenario of a tube camera, recorded by a 1" tape, played

>> to a tube telly. Once you involve computers you can make anything work by

>> storing and reading out frames how you like - but it had to work in the

>> good

>>

>> old days...

>> cheers - Jamie

>>

>> I knew it would be fun !!

>>

>>> From: Ryan Collier <rcollier(at)postcentral.com>

>>> Reply-To: DS(at)Softimage.COM

>>> To: DS(at)Softimage.COM

>>> Subject: Re: field dominance fun..?

>>> Date: Sun, 9 Oct 2005 12:09:52 -0400

>>>

>>> Jamie-

>>>

>>> --Are you saying that (in PAL) f1 starts scanning top-left with line  2

>> and

>>

>>> f2 starts scanning top-middle (the half line at the top) with  line 1?

>>>

>>> Yes, this is exactly right and describes the "field order" -- how the

>>> fields are laid down on tape.

>>>

>>> --And f1 is called upper, even though it starts on line 2 and there's  a

>>> half of line one above it?

>>>

>>> Yes, as far as I understand it. Remember though, while the UPPER  field

>>> (F1) comes first in the FIELD ORDER, the LOWER field (F2) is  displayed

>>> first, resulting in the EVEN DOMINANCE. For NTSC it is  opposite. LOWER

>>> field (F2) comes first in the FIELD ORDER, but the  UPPER field (F1) is

>>> displayed first, resulting in the ODD dominance.

>>>

>>> The terms "upper/lower" only apply toward FIELD ORDER. As in, "the  upper

>>> field is laid to tape first." It might help to think of it like  this:

>>>

>>> Whereas PAL is UPPER field first, a group of PAL frames might look

>>> something like this on tape:

>>>

>>>    Field 1           Field 2                 Field 3           Field 4

>>>       F1                F2           |          F1                F2

>>>     upper             lower                   upper             lower

>>> even scan lines   odd scan lines          even scan lines   odd scan

>> lines

>>>

>>>

>>> Whereas NTSC is LOWER field first, a group of NTSC frames might look

>>> something like this on tape:

>>>

>>>    Field 1           Field 2                 Field 3           Field 4

>>>       F2                F1           |          F2                F1

>>>     lower             upper                   lower             upper

>>> even scan lines   odd scan lines          even scan lines   odd scan

>> lines

>>>

>>> The picture is always reconstructed by drawing lines 1, 3, 5, 7, etc.

>>> first. And since line 1 of the PAL picture is contained in F2 (even)  DS

>>> sets the FIELD DOMINANCE to even for PAL sequences.

>>>

>>> Sort of like it asking, "Where can I find the 1, 3, 5, 7, etc. scan

>> lines

>>> of the PAL picture?" And being told, "you can find those lines  in F2,

>> the

>>> EVEN field, of the PAL picture." And so, the DS replies,  "Thank you, I

>>> will set myself to an EVEN DOMINANCE then for PAL  sequences."

>>>

>>> So, using our question/answer scenario again for NTSC:

>>>

>>> - "For NTSC, where can I find the 1, 3, 5, 7, etc. scan lines of the

>>> picture?"

>>>

>>> - "You can find those lines in F1, the ODD field, of the NTSC picture."

>>>

>>> - "Thank you, I will set myself to an ODD dominance then."

>>>

>>> Cheers,

>>>

>>> Ryan

>>> ---

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