Increase in program length between 23.98 and 59.94

[Rob Gardner]

Thanks for the many interesting responses. Frank, this is a PBS show, so there are no commercials. Whether or not the show changed length in actual time is an interesting concept, but not one I’m sure I would test by delivering the show long (or what appears to be long) when I am expecting a check based on its passing QC.

We have now done a total of 14 hours of various shows originating on Varicam and delivering either on D-5 or HDcam, and this problem seems to re-occur. You would think we would have figured it out by now… As John suggested this process continues to supply surprises.

Anyway, we are figuring out a formula that will get us close enough on the next shows we do. I’ll pass it on, but I wish we could put our finger on just what is happening.
Rob

[Frank Nolan]

[Rob Gardner] “Frank, this is a PBS show, so there are no commercials. Whether or not the show changed length in actual time is an interesting concept, but not one I’m sure I would test by delivering the show long (or what appears to be long) when I am expecting a check based on its passing QC.Rob”

Sorry Rob, I noticed that after I had posted. Also I wasn’t suggesting you send a show that was too long. All I was saying was if you take your original 1 hour NDF timeline and play it against a stopwatch you would find your program is actually 1 hour an 3.6 seconds.

[Rob Gardner] We have now done a total of 14 hours of various shows originating on Varicam and delivering either on D-5 or HDcam, and this problem seems to re-occur. You would think we would have figured it out by now… As John suggested this process continues to supply surprises.
Anyway, we are figuring out a formula that will get us close enough on the next shows we do. I’ll pass it on, but I wish we could put our finger on just what is happening.
Rob”

Let me try to explain exactly what is happening. NDF timecode does not reflect real time. If you have a NDF timeline that starts at hour 01:00:00:00 and ends at hour 02:00:00:00, the show will in fact be 108 frames (or approx 3.6 seconds) longer than 1 hour of real time, due to the fact that video is actually playing at 59.94 fields per second not 60.
This is the whole reason DF timecode was invented, to compensate for this discrepency. The simple solution and formula that has been in place for years is to have a timecode calculator/converter on hand when working with NDF material that has to be delivered in a DF format.

[Mark Raudonis]

The problem is that the engineers who created “drop frame” time code should have called it “Drop Number”! No “frames” are ever dropped… only numbers counting them.

This misconception has confused more people and generated more questions on boards like these than almost any other topic. Now with the actual frame rate differences between 24p, 25p, 30p, NTSC and HD, the “Drop/non-drop” issue only adds further confusion.

Bottom line: If you work in NON drop mode, and you care about hitting a “real” time (59:30 exactly), you MUST use a TC calculator to figure out your “real” time. As Frank says, “that’s why Drop frame was invented”… so you Don’t need a calculator.

Mark