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Reading KC at (25) 24.975/NTSC
- To: "TiG" <telecine at xyzoom.alegria.com>
- Subject: Reading KC at (25) 24.975/NTSC
- From: jpb <aaton.jp at alpes-net.fr>
- Date: Sat, 12 Jul 97 23:25:05 +0200
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- Resent-Date: Sat, 12 Jul 1997 14:26:00 -0700 (PDT)
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Ken Robinson/Imagen Transfer/Santiago 7/1/97 0:54 wrote:
> I have someone here in Chile who has a problem that I know
> someone out there can solve!!!
> He filmed in the UK at 25fps including Sound at the same speed.
> Then he flew back to Chile and transferred all the material
> to NTSC but at 25 fps. There wasn't any problem syncing the
> sound but now there is a worry about cutting the negative ...
You are right, the TIG is the best place to alert concerned
engineers about the (25fps) 24.975/NTSC transfers
which are becoming more and more frequent... and a real
headache. Our P-frame proposition below will only work if
manufacturers upstream and downstream the telecine
keycode-reader play the same game.
* Out of five film images [P A B C D] running at 24.975fps,
the 2:2:3:2:3 field repetition pattern delivers twelve
fields [P1 P2 A1 A2 B1 B2 B3 C1 C2 D1 D2 D3] which produce
six video frames [P1P2 A1A2 B1B2 B3C1 C2D1 D2D3] at 29.97fps.
We called the sequence *PABCD*, instead of *ABCDE* to avoid
confusion between the well known A-frame and the new edit
reference which becomes the P-frame.
1 - the telecine must deliver a repetitive 2:2:3:2:3 frame
pulse timing at 24.975/NTSC.
2 - the TK keycode-reader must tag the twelve P1 to D3 fields
and produce frame accurate lists under this mode.
3 - the TK edit-controller must insure edits on P-frames like
it does on A-frames in the 23.98/NTSC world.
4- and finally, the NLE must handle the '2:2:3:2:3' P-frame
sequence and deliver EDLs the way it does for '2:3:2:3'.
A conference in Santiago between the '24.975/NTSC willing'
manufacturers is upon you Ken :)
Jean-Pierre Beauviala http://www.aaton.com
thanks to The Post Group for support of the TIG in 1997
mailinglist digest available......posting guidelines on the webpage
the Telecine Internet Group <http://www.alegria.com/telecinehome.html>