Help Blacking a Tape/Time Code

[Derek Roff]

> If you are working in Non-Drop Frame, your 1 hour movie would
> actually be slightly shorter than 1 hour. (and that would be bad if
> you were broadcasting it and it went to black several seconds
> before it was supposed to be over)

The term "working in Non-Drop Frame" in the above statement is 
ambiguous, as is the situation that we are discussing.  We don't know 
exactly who is working on what, in what system.  Whether the "hour" 
of video is long, short or just right depends on whether, and how, it 
is shifted between drop-frame and non-drop frame.

An hour of broadcast, drop frame video displays 107,892 frames of 
video at 29.97 frames per second.  An hour of non-drop frame (30 fps) 
video would contain 108,000 frames.  So if you are editing in 
drop-frame, and "broadcasting" in non-drop frame, then the video will 
come up short by 3.6 seconds per hour, when broadcast.  If you edit 
in non-drop frame, and broadcast in drop frame, then the video will 
run long by 3.6 seconds.

Drop-frame exists because of the physics of wireless TV broadcasting. 
If a program isn't going to be sent out over the airwaves of 
broadcast television, then the difference in speed between drop-frame 
and non-drop frame has little importance.  For short projects, which 
the original posting mentioned, the difference in run time between 
drop frame and non-drop frame is easy to ignore.  So I am curious as 
to why this project seems to be specified in non-drop frame.

But it gets weirder.  The original posting quoted the specification 
as saying:  "all material should be striped at 29.97 NDF."  29.97 
frames per second is the drop-frame video speed.  30 frames per 
second is the speed for non-drop frame.  "29.97 NDF" seems like an 
untenable hybrid.

Can anyone explain "29.97 NDF"?  Am I suffering from brain lock, or 
is the film festival's specification confused?

Derek Roff
Language Learning Center, MSC03-2100
Ortega Hall Rm 129, 1 University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek at unm.edu