Green Screen with the 370

P

PointSource Media

New member
Hello all... I'll be shooting my first green screen footage with the 370 this week. Now I've done a ton with my Ikegami's throughout the years so lighting is not really anything I have a question about. It has more to do with which is better. Progressive or Interlaced. I'm guessing (of course) that I should shoot this at the best compression (100 MB Intra) and at the highest resolution. And for some reason I'm also guessing that progressive is better than interlaced but that part is only a guess. Does anyone here have any real world experience as to how to set up this camera to end up with the best key?

Thanks,

Paul
 
Definitely AVCI-100. Don't use AVCI-50, as that's only 4:2:0, you'll get twice as much color information with AVCI-100. 1080/24p or 25p or 30p will deliver the best results for keying, provided that the frame rates work for your shot (i.e., provided the film-look frame rate is appropriate). If you need the "live" look and want the best keying, I'd say 720/60p for that.
 
Thanks guys. That's what I thought. This will be just a sit down interview without a lot of motion so I believe 1080 30p will be fine. This will certainly not have any theatrical showing of any kind so other than that application is there any benefit to shooting 24p over 30p for anything?

Paul
 
Frame rate isn't about how it's going to be displayed. Frame rate is about movement. Things move differently in different frame rates. If you want the movement, the look, of 24p, then shoot with it. If you want the movement, the look, of 30p, then use it. If you want the look of 60i/60p (they're the same), then use it. Each has a different signature. Pick the one you want the look of.
 
Thanks David, being new to the camera (and owning an HD camera) I really don't know "how" each of these look different other than the amount of "judder" from one to the next. I will experiment this week. I admit to being a bit unclear in my mind as to how some of the settings "really" differ. Say from 1080-59.94i with the Recording format set to AVC-I 100/30P and to 720-59.94P and the Recording Format set to AVC-I/60P. Both will record the same (timewise) on the card. Barry had said the first here would be better than the second. How? I'm asking so that I understand not to be argumentative.

Thanks,

Paul
 
Again, it's about the kind of feel you want to your footage. Do you want it to look "live" like news or American Idol? Then you want 59.94, and you want progressive for greenscreen, so 720/60p (59.94p) is your best bet. 30p won't look live.
 
The judder is the primary difference. I'm saying progressive is better than interlaced for keying, so I'd go with 720/60p instead of 1080/60i, if you want the "live" look. If you want the "film" look, it's 1080/24p all the way. And only ever AVCI-100.
 
Great, I'm getting closer here but forgive me. I must be missing something. The trouble I'm seeing I have "getting" is this (and this is the real point of my last question. I'm sorry I may not have been clear enough). It's the part about the "System Mode" and the "Rec Format" The system mode ONLY starts at 1080-59.94i THEN (skipping 50i since I'm in the US) goes to 720-59.94P. Keeping with the AVCI-100 (as a given). Then with the 720- our Rec Format goes between AVCI-11/60P/30PN/or 24PN After that our Rec Format with the 1080-59.94i starts at AVCI-/60i/ 30PN/ans 24PN. So my real question (I guess) is this... With the System Mode in 1080-59.94i and the Recording Format in say 30PN. Is this camera really recording Progressive or Interlaced? With the System Mode in 720P AND the recording format in "One" of the PN modes then is this the only "true" progressive recording? I'm sure I'm missing something with this but this is the part that throws me. To be clear I don't understand the difference between "System Mode" and "Recording Format". And why (or how) one can be Progressive and one can be Interlaced and then we end up with a progressive end product? How's that for muddying up the waters?

Paul
 
The 59.94 simply refers to the base frequency (as opposed to 50 in PAL territories). In 30pN, it images and records only 30 progessive frames per second. In 24pN, it's 24.

It's very confusing, I know.
 
I've shot considerable amounts of green screen with the 370 and besides the frame rate of 1080 30P, i would suggest you dial down the detail in the menu to about -4 or 5 for starters. the 370 really does resolve 1080 rather well and detail artifacts on fine detail are your enemy when it come to keying. Keyes generally go better with less detail from cameras that have good optical resolving powers .
 
Thank you all for the replies. David the part I had more of a question is the part about the 1080i 30P as opposed to 720P 30p or 60p. This is my basic misunderstanding about the camera (or really about HD content I guess could be the truth). Why not 1080P 30P? And if the 1080 part is interlaced how is it shooting progressive? I believe you when you guys say it is. I don't doubt you. I would like to just understand for myself how this works. If there is an article you could direct me to instead of explaining this that would be great.
I know there's more to this than the simplicity of DVCAM. I welcome this. I like having the choices. One of the reasons I bought into this format over the Sony solution is the robustness of the codec. I read Barry's article on 4.2.2. color and finally "got it". That helped me a lot and I recommend everyone read it who is unclear at all on why this is better over 4.2.0.

And Mark, that makes perfect sense. Thanks for that. I will do a series of tests with different detail settings with a practice green screen interview in the studio before I shoot any more. I shot the first couple of interviews for this project before I got to read your reply. As I read it I did a head slap thinking right, why didn't I think of that.

Thanks again everyone.

Paul
 
It's just how they label it in the menus. They've been doing it that way since the HVX200; it's confusing as all heck, but that's how they do it. It's 30p. It's not interlaced.

As for why they do it that way, an imperfect way of saying it is that the base codec is 1080i, but it's been adapted to record 1080p.

All shooting at the sensor is progressive, not interlaced. For the interlaced recording modes, it's created out of the progressive frames.
 
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