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Re: f1 pr f2 the right picture?
- To: "bruce hancock" <fingers at dircon.co.uk>, <telecine at sun.alegria.com>
- Subject: Re: f1 pr f2 the right picture?
- From: "Michael D. Most" <mmost at encorevideo.com>
- Date: Mon, 1 Sep 1997 20:19:25 -0700
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- Resent-Date: Mon, 1 Sep 1997 23:14:08 -0700 (PDT)
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>In offine NL systems, I'm told that Avid 'digitize' and display field 1,
>where Lightworks record and display field 2 (both being at single field
>offline resolutions). Because of 3:2 pulldown, this would mean that for
>some time code numbers, Avid will display one frame while Lightworks
>will display the following frame. Is this taken into account when either
>of the systems output a neg cut list?
The confusion on this point is that many people think of Avid and Lightworks
systems as video editing systems. They are NOT. They are computer based
digital systems, and they do not know about or care about time code except
as a reference back to the original material, based on a time code/key
number ID of the first frame. Internally, they both use offsets from the
first logged frame to determine where in the clip they are, and they
mathematically translate that offset into a key number or a time code number
when you ask them to, i.e., when you generate a video EDL or a negative cut
list. In the case of the Avid, the field 1 digitizing simply means that the
"skipped" video frame during the digitizing process is always the 3rd video
frame in the sequence of 5 frames, because the first field of that frame is
the same film image as the first field of frame 2. In the case of
Lightworks, the "skipped" video frame is frame 5, because field 2 of that
frame is the same as field 2 of the preceding frame. Both schemes allow the
systems to track true film frames very accurately. If anyone wants a more
detailed explanation of how the 3:2 pulldown creates the above scenarios,
let me know and I'll post one.
Mike Most, Encore Video, L.A.
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