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24p, graphics and pans

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mark pigott
24p, graphics and pans
on Aug 6, 2008 at 7:27:54 pm


Before I describe the issue:
Here are my settings
XDCAM 24p 35Mps VBR

Using this sequence settings I have
brought in some graphics which I apply
a smooth pan from left to right.

I export the sequence using current settings, self contained

I import the QT to DVD Studio and set up for HD DVD 24p (or NTSC
DVD 29.97 SD-doesn't matter as I'll describe.)

Anyhow both the NTSC and the HD DVD look as though I have manually
moved the picture with my hand starting and stopping as I pan.

It seems as though there are way more frames than should be
(remember the test movie is one graphic, and one left to right pan)

The picture staggers across the screen rather than a smooth pan.

Do I have to do pulldown (as the playback pulldown settings
make no difference to the DVD.

I really want to bring in some 1920x1080 24p animations from
3d Studio but all my tests suffer from the same frame stutter
(whether in the viewer on on a SD monitor for SD DVD or a HD
monitor for HD DVD)

Any help would be appreciated!


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mark pigott
Re: 24p, graphics and pans
on Aug 6, 2008 at 8:50:18 pm

I'd just like to confirm that all the graphics in another HD movie
came in at 29.97fps (tifs and jpgs) EVEN though the sequence setting
is for XDCAM 24p 35Mbps VBR.

This certainly sounds like this could look like bad pulldown and wrong
frames causing stutter!

I will have to isolate each and every still (that is pan animated)
and change the frame rate to 23.976 manually- and hopefully this is
what caused the frame stutter issue


[mark pigott] "It seems as though there are way more frames than should be
(remember the test movie is one graphic, and one left to right pan)

The picture staggers across the screen rather than a smooth pan"


I got tipped off with this post
http://forums.creativecow.net/readpost/8/999303





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Oliver Peters
Re: 24p, graphics and pans
on Aug 6, 2008 at 9:48:40 pm

Mark,

I'm afraid you're never going to get smooth moves this way for these reasons:
1. 24P sequences are progressive and motion will only be updated every 1/24th of a second. All movement will have some stutter, which becomes more obvious as the speed increases.
2. When you import 29.97 movies into 23.98 projects, FCP does frame rate conversions that often result in blended frames and sometimes dropped frames.
3. Assuming you have the best looking image possible in FCP as 23.98, you can still add cadence (pulldown) to the files as part of the encoding or DVD player's playback. This can be any of 3 possible cadences, the worst being 2:2:2:4, which look most like dropped frames.

I'm not sure what to advise you to do, since it might mean starting over. The absolute smoothest moves you are going to get, when you view this on a TV set, is if you work in a 29.97 NTSC project and do all your moves in that environment - and FIELD RENDER your 3D animation. This way your moves are done in the interlaced world and will be updated 1/60th of a second and therefore be smoother. Unfortunately your XDCAM footage will not be cleanly converted by FCP. Your best bet is to "offline" with the native XDCAM HD footage, letting FCP convert it. Then find your selected shots and use AE or another app to turn the XDCAM-HD 23.98 clips into NTSC 29.97. In FCP, you will then have to manually replace the XDCAM-HD clips with the converted clips.

Another option is to build the entire sequence as HD 23.98 and export to a 24fps deck. Then reingest as NTSC 29.97. You'll get a better conversion and proper cadence, but the moves will still look like film, meaning that they might still strobe during faster movement. I realize you mentioned HD-DVD, but that is now a dead format, unless you have a specific application for it. With DVD-SP, you are limited to SD output, as far as something most folks can play.

Lastly, the issues you are describing will have a completely different look, depending on whether you are monitoring them on an SD CRT or an HD LCD or plasma. 480i/59.94 (29.97fps) looks best in the SD world, but 1080p/29.97 seems to be the sweet spot for HD sets (LCD or plasma). The latter still tends to look "strobed" (or film-like) when downconverted to an NTSC CRT.

Sincerely,
Oliver

Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com


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