3:2 pulldown in 24p looks bad! at DVinfo.net

Go Back   DV Info Net > JVC ProHD & MPEG2 Camera Systems > JVC GY-HD Series Camera Systems

JVC GY-HD Series Camera Systems
GY-HD 100 & 200 series ProHD HDV camcorders & decks.


Reply
 
Thread Tools Search this Thread
Old May 13th, 2006, 11:02 PM   #1
Major Player
 
Join Date: Mar 2006
Location: Sherman Oaks, CA
Posts: 471
3:2 pulldown in 24p looks bad!

When I shoot in 24p w/ my HD100 is it true that there is no way to view "true 24p" footage without transferring it to film first?

This question has to do with the way the camera stores 24p info onto the DV tape using the 3:2 pull down method.

I am learning that the 3:2 pull down is what causes the footage to look stroby, and that 24p viewed properly at 1:1 looks great.

It just seems that about every 1/3 second it looks like I'm missing a frame. It's the uneven frame rate that I'm noticing. Is this the 3:2 pull down I'm seeing?

What have people done to help this problem without spending the money to transfer it to film?

Thanks,

Scott
Scott Jaco is offline   Reply With Quote
Old May 14th, 2006, 12:29 AM   #2
Trustee
 
Join Date: Apr 2005
Location: Chicago
Posts: 1,214
Another way is if you NLE supports 23.98 and you're viewing it on a LCD. 24fps is smooth as it should be. Anything out to CRT will not look right and you'll get judder.
Stephen L. Noe is offline   Reply With Quote
Old May 14th, 2006, 01:39 AM   #3
Wrangler
 
Join Date: Oct 2002
Location: Los Angeles, CA
Posts: 2,100
Scott,

While your eye might be picking up on artifacts inherent in going from 24fps to 60i video, you do understand that productions have been doing this for eons and audiences don't find fault with it like you are, right?

It's good to develop your eye and be able to spot defects in your material before your clients do, but it also helps to know which defects are inherent to the medium and that you can't do much about.

I've noticed this a lot on the boards lately...as soon as all the new HD cams showed up, many boards turned into a huge "spot the chromatic aberration" game...despite the fact CA is present to one degree or another in just about any lens manufactured. Same goes for 24fps->60i telecine conversions.
__________________
My Work: nateweaver.net
Nate Weaver is offline   Reply With Quote
Old May 14th, 2006, 01:48 AM   #4
Trustee
 
Join Date: Apr 2005
Location: Santa Cruz, CA
Posts: 1,116
Scott.

You can do a simple test if your transfer to NLE worked. Play 1 second of footage frame by frame. Each frame should look like a "real frame" with no blending between them. Also check that you have the Smooth Motion in the OFF position.
__________________
Paolo http://www.paolociccone.com
Demo Reel
Paolo Ciccone is offline   Reply With Quote
Old May 14th, 2006, 02:47 AM   #5
Major Player
 
Join Date: Apr 2005
Posts: 512
Quote:
Originally Posted by Stephen L. Noe
Another way is if you NLE supports 23.98 and you're viewing it on a LCD. 24fps is smooth as it should be. Anything out to CRT will not look right and you'll get judder.
How is an LCD different than a CRT in terms of refresh rate? LCDs don't magically eliminate pulldown, they refresh at a constant rate just like CRTs, and if that rate is not an even multiple of 24 you will get pulldown problems just like a CRT.

In fact thanks to NTSC's non-integral refresh rates (i.e. 29.97 instead of 30), and the fact that computer monitors tend to refresh at integral refresh rates, there's no way to avoid pulldown in the end.
Stephan Ahonen is offline   Reply With Quote
Old May 14th, 2006, 09:04 AM   #6
Trustee
 
Join Date: Apr 2005
Location: Chicago
Posts: 1,214
Quote:
Originally Posted by Stephan Ahonen
How is an LCD different than a CRT in terms of refresh rate? LCDs don't magically eliminate pulldown, they refresh at a constant rate just like CRTs, and if that rate is not an even multiple of 24 you will get pulldown problems just like a CRT.

In fact thanks to NTSC's non-integral refresh rates (i.e. 29.97 instead of 30), and the fact that computer monitors tend to refresh at integral refresh rates, there's no way to avoid pulldown in the end.
To send to NTSC CRT monitor you MUST send 29.97. When viewing 23.98 on a timeline it is viewed at the framerate that the timeline dictates into it's master viewer.

If I take 23.98 and put it on a 29.97 timeline in order to view it on CRT the judder is introduced automatically. When I view the 23.98 on a 23.98 timeline in the master viewer there is no judder on LCD, but the CRT always reads "Not Supported" for 23.98 where the LCD will go ahead an display the 23.98 properly.
Stephen L. Noe is offline   Reply With Quote
Old May 14th, 2006, 11:50 AM   #7
Major Player
 
Join Date: Mar 2006
Location: Sherman Oaks, CA
Posts: 471
Quote:
Originally Posted by Paolo Ciccone
Scott.

Also check that you have the Smooth Motion in the OFF position.
Really? It's actually turned on. Why does this cause more artifacts?
Scott Jaco is offline   Reply With Quote
Old May 14th, 2006, 12:01 PM   #8
Trustee
 
Join Date: Apr 2005
Location: Santa Cruz, CA
Posts: 1,116
Quote:
Originally Posted by Scott Jaco
Really? It's actually turned on. Why does this cause more artifacts?
There you go, that's what screws your frames up. That circuit basically bleds frames together creating a blurred image that is supposed to create the illusion of smoother playback. If you look at the frames one by one you'll be able to spot the blend. Turn it off and try shooting again, it should be better.
__________________
Paolo http://www.paolociccone.com
Demo Reel
Paolo Ciccone is offline   Reply With Quote
Old May 14th, 2006, 12:31 PM   #9
HDV Cinema
 
Join Date: Feb 2003
Location: Las Vegas
Posts: 4,007
Quote:
Originally Posted by Scott Jaco
I am learning that the 3:2 pull down is what causes the footage to look stroby, and that 24p viewed properly at 1:1 looks great.

It just seems that about every 1/3 second it looks like I'm missing a frame. It's the uneven frame rate that I'm noticing. Is this the 3:2 pull down I'm seeing?
There are three artifacts you may be seeing:

1) Eye tracking artifact (strobing) that comes when the same frame is re-exposed. This happens with film when it projected with a dual-blade shutter that flahes the pix twice. Thus film is flashed 48 times/second. This happens with 25p and 30p when they are viewed on a monitor that flahes the pix twice -- at 50/s or 60/s. You control this by keeping the shutter speed a bit slow AND by controllimg the rates of motion of the camera and/or subjects. Some call this artifact "judder."

2) Judder (unevenly spaced distrubance) when 24p is shown on a 60p or 60i monitor. This is from pulldown.

3) Repeated frames that come when 24p is converted to 30p.

4) Dropped frames that come when 30p is converted to 24p.


Frankly, your 1/3 second effect is likely pulldown.

When you shoot 24p you do NOT want the motion filter ON -- as folks have said.

When you shoot 30p, however, the blended frames help reduce strobing. They create artifical motion blur. Tim hates the look, but I like it because on moving objects it creates a bit of judder that looks, to my eye, more acceptable than pure strobing. That's because we are all used to seeing judder with film.
__________________
Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c
Steve Mullen is offline   Reply With Quote
Old May 14th, 2006, 05:52 PM   #10
New Boot
 
Join Date: Apr 2006
Location: Hollywood, CA
Posts: 22
Hey Scott, Paolo and everybody,
I just installed the Prospect HD plugins for Adobe Premiere and was nicely rewarded with being able to view 24FPS footage on my producer monitor at the studio, which means that if you install this software and hardware solution, you can work in 24P but view NTSC 29.97 FPS and output to tape directly from the timeline. It's pretty cool
Check it out on www.cineform.com


Ben Jehoshua
Ben Jehoshua is offline   Reply With Quote
Old May 14th, 2006, 05:54 PM   #11
Major Player
 
Join Date: Oct 2002
Location: Glendale, AZ
Posts: 217
I just did a small test using pablos settings and shooting 24 p advanced in SD mode and editing on Vegas 4 dvd. It came out great. It was easy using vegas. I did not have to do anything different because the program recognized it was 24 p and did everything automatically. I burned it on a dvd and it looked like 16mm film. One problem I have is a very old dvd player. I get lots of pixels and all kinds of garabge. I know it is the player because everytime I played it different things show up at different places on the dvd.
It also might be the dvd's I use. Any suggestion on a HIGH quality dvd-r?
Also I captured using my canon opturera 60 consumer camera with no problems.
Joe Bowey is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > JVC ProHD & MPEG2 Camera Systems > JVC GY-HD Series Camera Systems

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 09:30 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network