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View Full Version : Capture format for editing outside VT - Keying



jsanfilippo
07-15-2007, 07:42 PM
Hey all,

I am going to do some chromakeying on Monday, and I know that I will get best results capturing component video and recording as RTV, for keying in post later. Problem is, I want to be able to edit in either Vegas or FCP. (I NEVER use my live VT machine for editing!!!)

If I capture as RTV, will I run into problems trying to dump that into either Vegas or FCP? Any way to avoid potential problems?

ScorpioProd
07-15-2007, 10:12 PM
Well... The only way to use RTV with Vegas would be if you put it in VT and saved it via the AVI Wrapper...

Problem is, NO Newtek codec, which is based on YUV, will show up with proper video levels and colors in Vegas 7, which is RGB based. I love Vegas 7, but it is not a good program for sharing VT or SpeedEDIT projects with. Vegas only properly understands the RGB equivalents for DV and HDV and the GV HQ codec.

If you put a clip into Vegas using a Newtek codec like the wrapped AVI, SpeedHQ or NT25, you will need to apply a color correction filter to it using the "Computer RGB to Studio RGB" preset to correct it to proper levels and colors in Vegas.

As for Final Cut Pro, no way to use RTV there.

It's important to remember that RTV is a SD-only proprietary format which Newtek now only considers a legacy format. It was never really made for use in other applications outside of Newtek products.

jsanfilippo
07-16-2007, 05:17 AM
Thanks Eugene,

So to distill this down to steps....

1) Capture as RTV (I don't use RTV much - any particular settings??)
2) Dump into VT-Edit and rerender as AVI, NT25
3) Dump AVI into Vegas
4) Apply Primary Colour Corrector to entire file, using template Computer RGB to Studio RGB
5) Proceed with edits and chromakey

Is that correct?

Will that colour correction step make keying any more difficult? It should alter all colours the same, so any shift will be made across the board. Right?

ScorpioProd
07-16-2007, 11:17 AM
1) There are no settings for RTV, so just capture RTV.
2) Put the RTV clip or clips into VT-EDIT and save as a wrapped AVI, no "rendering" needed. Though if you render to NT25, that's a good solution as well.
3) Put the AVI in Vegas.
4) Color correct using "Computer RGB to Studio RGB" template. (You can do this at clip level or on the whole track if it's a bunch of clips.)
5) Proceed with edits and chromakey.

The color correction shouldn't make keying more difficult, it is across the board as you say.

Note that color correction in Vegas does tend to be a significant processing load, unlike in VT-EDIT or SpeedEDIT, so you will see your preview framerate go down a bit.

Also note that Vegas is 8-bit RGB internally, so too much color correction can result in issues with YUV footage. But this really isn't a big color change, so it should be fine.

BTW, what format are you going to come out of Vegas with?

jsanfilippo
07-16-2007, 05:17 PM
Thanks again, Eugene.

This worked fine today. Only problem was my lighting was just a little bit off on the greenscreen... it was a little hotter on the bottom than the top.

From your experience, does VT-Edit (i'm not working with Speededit) have better chromakeying capabilities than Vegas 7? I can't quite get a perfect key with Vegas because of the slight "gradiant" of the background. I'd prefer not to reshoot.

To answer your question... out of Vegas.... will use DVD Arch. to burn to DVD, as well as render to AVI for live playback on VT. Why do you ask?

Jim_C
07-16-2007, 08:26 PM
Use uncompressed avi if the RTV thing falls thru and you have disk space.

From my experience VT has a 'decent' keyer if you use uncompressed from a nice component source.


Give it a try, can't hurt anything.

ScorpioProd
07-16-2007, 09:12 PM
From your experience, does VT-Edit (i'm not working with Speededit) have better chromakeying capabilities than Vegas 7? I can't quite get a perfect key with Vegas because of the slight "gradiant" of the background. I'd prefer not to reshoot.

Personally, I've never needed to do chromakeying, so I can't give any advice on that. Sad, but true.

But like Jim says, it's worth a shot trying it in VT-EDIT.

Also note, you were only talking video, and I forgot to mention, I haven't had much luck with audio through the AVI Wrapper to Vegas, so I would recommend rendering out a WAV from VT-EDIT if you need audio with your video in Vegas.



To answer your question... out of Vegas.... will use DVD Arch. to burn to DVD, as well as render to AVI for live playback on VT. Why do you ask?

I asked for a good reason, of course. :)

Doing the render in Vegas or DVD Arch would be fine, based on your color correction, but note that if you're rendering to AVI to playback on VT, you need to reverse your color correction to make the levels again correct for VT. This would be the "Studio RGB to Computer RGB" preset to go out, opposite of how you corrected coming in. Or actually, it would involve removing the initial color correction for the render to AVI, which would be the better way to do it, as long as that doesn't screw up the keying you did. In Vegas, with track based effects, this would be easy to do.

So, IF you were only going to be using the video as an AVI as your final output back to VT, you could ignore doing ANY color correction at all, and though it would be off a bit, with colors slightly oversaturated and luma with an illegal contrast range, while you were in Vegas, it would be fine back in VT.

See what I mean?

Cineman
07-16-2007, 10:56 PM
From your experience, does VT-Edit (i'm not working with Speededit) have better chromakeying capabilities than Vegas 7? I can't quite get a perfect key with Vegas because of the slight "gradiant" of the background. I'd prefer not to reshoot.
Jamie,

I read this as your now saying that you would be willing to do the edit in VT Edit if it will do the job, rather than to re shoot? If that is the case, try the Cross Keyer, as that will allow you to key out a range. It should handle your slight "gradient" easily.

Nes Gurley

SBowie
07-17-2007, 10:30 AM
Without getting into a huge amount of detail, there are a lot of advanced techniques that can permit you to do
preliminary corrections for green/blue screen defects before pulling the raw matte. One of the best books I ever
read on the subject is Digital Compositing for Film and Video, and it details many approaches.

One method in particular came to mind when I read this thread, so I spent a little time putting together a
tutorial on it for y'all. You can find it here: Screen Leveling Tutorial (http://www.vtworx.com/Resources/tutorial/screen-level/mir_level.html)

Here are before and after images so you can see the intended goal:

http://www.vtworx.com/Resources/tutorial/screen-level/problems.jpg

http://www.vtworx.com/Resources/tutorial/screen-level/FINAL.jpg

(Note that this scene really didn't need much help, but serves to illustrate the technique reasonably well anyway.)

Cineman
07-17-2007, 10:52 AM
Or open the Cross Keyer. Click and hold down the mouse pointer. Drag it over the wrinkle, the falloff range, and the shadow area. Release the mouse, and done.

SBowie
07-17-2007, 10:56 AM
Nes, you know I've had the Cross Keyer for quite a few years ... handy as it is, there are lots of things it can't handle, which is why a newer keyer is in the wings (and in use in TC-S) - but even then you can often run into countless problems where more advanced techniques become useful - even with very expensive dedicated keying plugins.

Cineman
07-17-2007, 11:07 AM
But wouldn't you agree that the Cross Keyer can handle Jamie's described problem and your example quite easily and simply?

SBowie
07-17-2007, 11:17 AM
But wouldn't you agree that the Cross Keyer can handle Jamie's described problem and your example quite easily and simply?I don't know - I haven't seen any of Jamie's sample footage. However, I've been asked at times to rescue very badly blown out footage, and had to use every trick in the book to do so, Nes. I'm not suggesting it is *always* necessary to use advanced techniques.

If you look at the tutorial - you'll see the notation following:


"The sample clip above is actually pretty good. The foreground is sufficiently distinct from the background that keying the shot is fairly simple. (Something that helps a lot is that - for once - the background is not harshly overlit, with very saturated greens, deep shadows, blown-out highlights and nasty spill.)

Nevertheless, we can see that there are some wrinkles, a bit of vertical lighting falloff, and some shadows caused by waviness in the green material. The deviation is not really very severe, but we'll use these minor shortcomings to demonstrate the Screen Leveling technique.

jsanfilippo
07-17-2007, 11:22 AM
Thank you for the suggestions, Nes and Steve.

Wow - what an indepth tutorial, Steve. Time is such that I don't have enough to go through your tutorial now and figure it out... but I certainly will in the coming weeks. Looks fascinating.

I will give the cross-keyer a shot to see how it does.

Incidentally, a little more tweaking of the Vegas keyer and I got a fairly decent key anyway... but I'm very interested in these two alternate (better?) solutions.

Thanks gentlemen!

SBowie
07-17-2007, 11:29 AM
If that is the case, try the Cross Keyer, as that will allow you to key out a range. It should handle your slight "gradient" easily.The Cross Keyer is very easy to use, but I don't think I've ever seen a keyer that doesn't allow you to key out a range. Where the problems begin is when the background deviation is extreme enough to require a large range. A common example would be a nearly blown-out hotspot on the background behind a fringe of fair hair ... but there are plenty of other occasions when you can start to encounter transparency in the foreground.

A variety of tools and techniques can help when you run into problems (typically when you have to use supplied footage.) Screen Leveling is just one, but it's an interesting one. These techniques are like spare tires - you don't use them until you need them, but when you do they can save the day. (BTW, this one is basically a variation of a Primatte feature.)