In SMPTE - Why the ";" in DROP and then :

Grazie wrote on 2/4/2012, 1:18 AM
I wake up screaming in the middle of the night about this kind of stuff. But "why"? - Not me screaming.

I really do understand the reason for DROP in SMPTE. But why the choice of semi colon ";" for "DROP" SMPTE as the far right field separator?



Steven Myers wrote on 2/4/2012, 2:59 AM
In a version of BASIC I used many years ago, using the semicolon was the only way to send a value to the telephone modem but prevent the addition of a CR/LF.
Grazie wrote on 2/4/2012, 3:45 AM
Sure, so/but why here?


farss wrote on 2/4/2012, 4:01 AM
Why not?
I know that sounds trite but it probably is as simple as that
I can think of good reasons to be able to easily know if it's drop or non drop.
Using ":" and ";" to denote one or the other is very simple on the eye and probably quite easy on the old hardware that first had to cope with this.

Grazie wrote on 2/4/2012, 6:19 AM
No, I don't think you're being trite at all. I was just hoping for an insight into the vagaries of TC and the proclivities of programmers/camera operators wanting more control.

Chienworks wrote on 2/4/2012, 8:09 AM

1:23:45;06 and 1:23:45:06 may look the same at first glance, but since one uses drop frame and the other doesn't, they actually differ by about 5 seconds. That's a critical time difference when a network is trying to sync a broadcast.

Changing the : to ; is a visual cue as to which timecode is being used.


How odd. Without the first line of "test" at the top, this post gets blocked. With it there, it goes through successfully.


Hmmmm. I don't think i said that well. Chronologically by the clock the two timecodes are the same, but the position in the file differs by 5 seconds' worth of frames.
rs170a wrote on 2/4/2012, 8:15 AM
NTSC Time Code tutorial (a 6 page pdf from Leitch).

monoparadox wrote on 2/4/2012, 8:29 AM
That was more than I ever wanted to know about SMPTE.

Some of you guys are obscure . . . but relevant. :-)
Former user wrote on 2/4/2012, 9:10 AM
Working in the linear tape world of editing most of my career, the semi-colon was a visual indication of the drop code vs. non-drop. When doing spot editing, we normally edited with non-drop tc. Made the math a lot easier and you could start spots at 1 minute even. When doing program length, we normally used drop.

Early edit/machine controllers could not always determine the drop frame status and you would have to set the status manually. This visual indiction was important.

Dave T2
larry-peter wrote on 2/4/2012, 10:01 AM
Dunno if this is relevant, but CMX 3600 EDL format originally used a data field specifying drop or non-drop TC and all TC entries used colons. When Grass Valley introduced their EDL format, it did away with the TC data field and began using colons and semicolons to differentiate drop from non.
Former user wrote on 2/4/2012, 11:22 AM
I never used CMX but you might be right. Grass Valley came on pretty strong in the earlier machine control/switcher days. I started on Datatron and then our proprietary controller.

Dave T2