Drop Frame vs. Non-Drop Frame

[EmployedStuntman]

I have an MPEG 2 encoded from a film with a 3:2 Pulldown on it (the Player will perform the telecine from 24.97fps) Anyway, should I set the drop-type to Drop Frame or Non-Drop Frame in Scenarist.

Thanks.

[mpucoder]

Rule of thumb (or any other convenient digit) NTSC uses drop frame time code, PAL does not.

[liquidnumb]

also a good piece of infor to know about drop fram and non drop frame just in case you are curious, drop frame is real time according to a clock. It of course drops a frame to keep up with a real clock becuase if it didn't it would be slightly slower than a real clock. the non drop doesnt of course drop a frame and it takes a a little longer than a second to get through 30 frames.

[SomeJoe]

Originally posted by liquidnumb
also a good piece of infor to know about drop fram and non drop frame just in case you are curious, drop frame is real time according to a clock. It of course drops a frame to keep up with a real clock becuase if it didn't it would be slightly slower than a real clock. the non drop doesnt of course drop a frame and it takes a a little longer than a second to get through 30 frames.

The video does not change speeds between drop-frame and non-drop-frame timecodes. NTSC video always runs at 30000/1001 = 29.97 frames per second no matter what timecode is used.
Actual video frames are not dropped. All frames are always shown no matter if the timecode is drop-frame or non-drop-frame. The only thing that is "dropped" is a particular frame number. Drop-frame timecode skips certain frame numbers so that the timecode always counts as if it were real-time. Non-drop-frame timecode never skips any numbers, so it does not match real time.

[mpucoder]

This is why it is called "drop frame time code", but people leave off the "time code" part, adding to the confusion.

And to add a little known fact about NTSC, the frame numbers dropped are always (if encoded properly) frames 0 and 1, as a pair. This is known as a super-frame, required to keep the color subcarrier in phase (for the math, there are 227.5 cycles of color subcarrier per line. 262.5 lines per field means each field is 59718.75 cycles long, or 270 degrees out from the previous. So it takes 4 fields, or 2 frames, to come back in phase.)