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RE: conforming the neg.

>So what happens on non-standard formats like 3-perf or 2-perf?

There's a dot every 64 perfs: in 2-perf that's not really a problem, the
dot will occur every 32 frames. 

But in 3-perf, it's harder. The dot appears every 21 1/3 frames - so in
practice we can count either 21 or 22 frames between dots, depending on
where the sequence started.  Logging systems need to specify whether a
logged frame has the dot at perf 1,2 or 3. It all starts to sound a bit
like 3/2 pulldown and A,B,C,D frames.  What can possibly go wrong?

Has anyone heard of a successful, frame-accurate match back to negative
in 3-perf for a film finish?   > 

Actually, Warner Bros./Lorimar has been cutting 3 perf negative for years (since about 1987). Originally, when the negative cutting department was part of MGM Lab (RIP, sadly), we had some synchronizers built with custom sprockets and counters that allowed us to count up to 63 frames, thus allowing an accurate count but only being able to use every 3rd key number. This continued with the aid of some software developed by Laser Edit that is still in use at Warners' to this day. Of course, this was before the introduction of Keykode (we used good ol' key numbers, you remember -- G25X40763, or something like that?). The more modern method of counting 3 perf is to use a 21 frame rollover for the first 2 keys (the count rolls over after +20 frames) and a 22 frame rollover for the 3rd (the count rolls over after +21 frames). This is the scheme used by Evertz and, I believe, Aaton, as well as Lightworks and in the near future, Avid. In these systems, the 3rd key is predetermined to be the one with the perf dot on perf 3.  In those early days, we had problems primarily related to 3:2 pulldown considerations (there weren't any 24 frame video editing systems at the time, we were using Ediflex). Today, Warners assembles 3 perf negative on many of their sitcoms which are shot using that format.

Mike Most, Encore Video (ex-Lorimar!), L.A.

thanks to Gary Shaw of Pacific Video Canada for support of the TIG in 1997
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