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Field Dominance ??

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Kevin Reinicke
Field Dominance ??
on Mar 4, 2009 at 12:25:07 am

Hey guys,

I shot a music video on the HVX200 in 720p 24p (1280x720) and need to deliver both in PAL and NTSC for satellite broadcast. When rendering from Vegas to 720x576 interlaced (PAL) or 720x480 interlaced (NTSC), im not sure abt the Field dominance, is it upper field or lower field first????

Also: in order to preserve the 16:9 aspect ratio of the video, do I have to set the pixel aspect ratio to 1,093 ???

Thanxs guys,

K.R.


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Dave LaRonde
Re: Field Dominance ??
on Mar 4, 2009 at 1:03:14 am

Glad you got it shot, and I hope to God you haven't started capturing or editing. You've got yourself some issues you haven't even considered. Field order is the LEAST of your worries at this point.

[Kevin Reinicke] " in order to preserve the 16:9 aspect ratio of the video, do I have to set the pixel aspect ratio to 1,093 ??? "

Let's start with this one. How do you propose to put your 16x9 video on a 4x3 screen? Letterbox, where you have black stripes at the top & bottom? Center punch, where you fill the screen but lose the sides of the video? Anamorphic, where the entire 16x9 picture is squeezed horizontally to fit into the 4x3 frame?

[Kevin Reinicke] "...HVX200 in 720p 24p... and need to deliver both in PAL and NTSC for satellite broadcast"

Did you shoot in 24p or 24pn? One has 23.976 frames/sec distributed across 59.94 frames/sec using 3:2 pulldown. The other has the files already at 23.976. If it's 24p, REMOVE THE PULLDOWN RIGHT NOW. Yes, I understand that in Vegas you can work just fine in 24p without removing pulldown, but what happens when you export? Is the resulting exported frame rate 23.976 or 29.97? If it's 23.976, life is good, and you can ignore what I said about removing pulldown. But the key to do BOTH PAL and NTSC is to use 23.976 (aka 23.98) frames/sec. You MUST have that.

Then, your notion of frame rate conversion is just a little bit simplified: you don't just toss video at one frame rate into a timeline of a different frame rate and expect miracles to happen.

My suggestion for going to PAL is to conform a COPY of your completed video at 23.976 to 25 frames/sec. Yes, it will run a little shorter because of the slightly faster frame rate, and yes, the pitch of the audio will rise a bit, but you can fix the audio and nobody will notice the change in video. It's the easiest way to fix it. Otherwise, you can go to a production house to use something like a Teranex box to convert from 23.976 to 25, with NO change in duration nor change in pitch. It should only cost you something like $2000/hour.

Going to NTSC is a lot easier: add the pulldown back to create 29.97 video. Heck, Vegas may do that for you automatically.

That's enough to get started, I think. Time to go home.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kevin Reinicke
Re: Field Dominance ??
on Mar 4, 2009 at 8:23:30 am

Dave,

thank you so much for your answer,

I shot in 23,976 and abt your question: I would rather like the video to be seen on a 4:3 screen with letterbox.

abt the framerate: for NTSC the vid is on its 1280x720 progressive timeline that I worked with and I render it out to 720x480 i and no matter what I do, Sony Vegas always gives me lower field first.

abt PAL: I never really got how to conform a file in sony vegas, so my rendering to 720x576 i PAL didnt used to look good. I opened to the final output (1280x720 p) in quick time pro und exported it out to PAL 720x576 i and it looks GREAT ! a very good conversion from 23,976 p to 25 frames interlaced. The file is upper field first though.

so now I have a NTSC version 720x480 i at 29,97 and lower field first

and

a PAL version 720x576 i at 25 and upper field first.

does that make any sense??




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Mike Smith
Re: Field Dominance ??
on Mar 4, 2009 at 9:07:12 am

The PAL depends a bit what format / codec you are using.

PAL is normally upper field first, apart from the DV family of formats (DV, DVCAM, DVCPro) which are lower field first.

Except Matrox produced a DV codec with upper field first that was in use with some of their hardware for a while .. which is non-standard, not supported by anyone else, may have largely died out.


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Asmund Voll Tesdal
Re: Field Dominance ??
on Mar 5, 2009 at 6:13:43 pm

[Kevin Reinicke] "I would rather like the video to be seen on a 4:3 screen with letterbox."

Did you check with whoever is broadcasting this? Some places here in PAL-land, at least, prefer anamorphic.



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