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Old January 6th, 2009, 11:07 PM   #1
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Question about deinterlacing, field order

I have been reading conflicting info about this. On the one hand I read that if the source data was HD (like from the new HD camcorders) that you want to choose Upper First. On the other hand, I have read that the choice is actually based on your intended viewing medium and that Progressive Scan is recommended for computer monitors. I am just trying to figure out how these settings should be made for HD video that I am trying to put on the web (which I know defeats the purpose of HD...).

Eventually I want to make DVDs and I am also curious how one would make such settings consistent given that a DVD will have many playback mediums (computers, TVs).

Regarding deinterlacing, not sure what guidelines determine when that is necessary. Again I read conflicting info, some saying it is based on the source and some saying it is based on destination.

Also, how do deinterlacing and field order relate?

Lastly (sorry for so many ?s), if you choose a field order method in project proprties, do you also make same selection in render setting or would that cause weird effects (i.e. some sort of serial processing). In other words, if you choose upper first in project settings and none in render, would net effect be upper first?

thanks,

brian
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Old January 7th, 2009, 06:24 AM   #2
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Brian, one place you might try is Sonys on-line help ... accessible via the help menu in the Vegas version you're running.

There's up to date info there right from the horses mouth.

Cheers.
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Old January 7th, 2009, 10:27 AM   #3
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HDV is mpeg2-based and is upper field first.
SD dvd's are also mpeg2 so they are upper field first.
SD minidv is lower field first.

For the web, you should have a progressive image because viewing will be done on a computer monitor which is progressive and therefore the interlaced lines with show up.

An SD DVD with the best playback potential on tv's and computers would be a 24p + pulldown dvd that will playback as progressive when the dvd players remove the pulldown.

Deinterlacing can be just removing the fields and making progressive frames without changing the frame rates such as have a 60i(29.97fps) file becoming a 30p file or it can be converting from 60i/29.97fps to 23.976/24p with programs like DVFilm Maker. Deinterlacing and field order only relate in that fields are in simple terms converted into frames.

Generally, you want to keep your field orders the same while editing.

Best,
Andy
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Old January 7th, 2009, 11:19 AM   #4
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The problem is 60i has a temporal rate of 60 frames per second. The convention is to say 60i(29.97fps) however each field is recorded 1/60sec apart ( its only half the vertical resolution but it is 60 times a second NOT 30). So each odd and even field cannot just be added together to make a real frame. One can leave half of them out and interpolate the other field to get to 30P but this introduces motion judder not present in the original 60i as seen on a CRT. Elaborate delinterlacing attempts to create a 60P rate if the display can manage this or some of the latest LCD's will take in a 60i input and create a 120fps display by interpolation. Personally for DVD I like 60i and let the playback system manage the display, nice smooth playback on a CRT or newer LCD or plasma and also some DVD players will upscale and deinterlace to 1080P30. For the WEB or PC playback there will have to be a compromise to deinterlace. Easiest is likely 30P.
You will get the most judder and playback problem with 24p. Film is shot at 24fps but the playback on a film projector also flashes the image up to 5 times per frame( 5 blade shutter) ie 120 refreshes a second. 24 does not divide equally into 60 either for TV set playback or PC playback so frames have to be repeated some 3 times some twice (3:2 ) which introduces a judder in the image. Some people like this video effect I do not. Newer players will send a true 24p image over HDMI to a display that is capable of playing this correctly( newer 120HZ LCD and plasma displays attempt to reproduce the film projectors flicker rate)

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Old January 7th, 2009, 11:37 AM   #5
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The general run of thumb I've been advised to follow by that VASST guys for Vegas is to set up your properties to match the source material. If you shoot 60i you would set up the timeline as a 60i, upper field first, and match the pixels to the footage that was shot.

When you render you do not have to match your timeline properties. You should render with the properties needed for your final delivery media. If you are going to a computer it does need to be progressive or you will get some pretty ugly results. I prefer progressive even on dvd's. The player will either send a progressive signal or an interlaced signal depending on the output connection (composite, S-video will be interlaced, HDMI and component will then come out progressive).

To avoid some of the judder that RonE mentioned if you start with interlaced material, you need an intelligent program that will not just throw away data or try to combine adjacent frames. There are some good programs out there and you can find some info in the forums if you do a search for deinterlacing. I would recommend shooting either 30P or 24P that way you start with progressive footage.

I would imagine for the instructional videos you want to make that you would want the look of 29.97fps rather than the 24P look which will give a slight motion blur.
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Old January 7th, 2009, 12:49 PM   #6
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[QUOTE=Garrett Low;990569]The general run of thumb I've been advised to follow by that VASST guys for Vegas is to set up your properties to match the source material. QUOTE]

What if you have two or even three different types of source material. How do you choose which one to match?
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Old January 7th, 2009, 01:20 PM   #7
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I did do a project where I had HDV and SD DV mixed in the same project. I set up the timeline to match the HDV settings. I shot both cameras in 60i which meant that the HDV was UFF and the SD was LFF. I used UFF on the timeline and rendered out to 24P to get a certain look.

Here's a link to a sample of the result:

School Sample Vid 1 on Vimeo

You can see the motion blur but that was an affect I wanted. The lighting was horrible and I couldn't do anything about it. The Lighting Director wanted it dark for the whole show which was primarily Traditional Chines Dancing.

I will generally set the timeline to the highest quality video I have on it. I have mixed 60i, 24p and 30p footage into one project. For that I convert all files to 24p and deal with the slight loss of resolution as my ultimate delivery was SD DVD that was coming from HD footage so the resolution drop was not noticeable.

Garrett
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Old January 7th, 2009, 01:37 PM   #8
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Ok, so you are saying for good computer playback with my 60i stuff, I need to deinterlace first and make it essentially 30p? I see mention below of DVFilm Maker but I thought Vegas does this? In other words, if my project is 60i and in project properties I choose Blend deinterlacing, will that produce 30p or will it be a weird 60i that has had half of its information discarded. I think I am almost understanding the heart of the matter here. The key for me is I want the proejct to always be 60i and I want to be able to render for different playbacks.

So then maybe I keep the project settings as Upper Field no deinterlacing and then render settings Progressive with Blend deinterlacing? Still not sure if that will result in 30p or if will simply be 29.97fps but progressive (which reading below sounds like the best option).

thanks,

brian
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