With a small 't', timecode is a numerical system
used in video editing
SMPTE (pronounced "simpty") timecode, used in conjunction with a videotape's control track, assigns every frame of video on a tape a unique number. Every frame has it's own "name", which is spelled out in hours, minutes, seconds and frames. It looks like this:
which is read as "one hour, thirty-four minutes, fifteen seconds and 29 frames".
Timecode counts upward as you are used to time doing, with 60 seconds to the minute and 60 minutes to the hour. There are 30 frames to the second...
Kind of. This is where things get funky.
There are two types of timecode. One is called Non-Drop Frame and the other is called (not surprisingly) Drop Frame. Non-Drop Frame, or NDF timecode, uses the simple 30 frames per second counting system. This was devised because people refer to NTSC video as having a frame rate of 30 frames per second (fps). Unfortunately, it doesn't. It did originally, but it hasn't since color TV was invented.
NTSC video's frame rate is actually 29.97 fps.
As such, if one is using NDF timecode, a discrepancy between the timecode and the actual "absolute time" runtime of the video footage appears, and worsens as time goes on. At a rate of .03 frames per second that adds up pretty quickly, and if you're brodcasting video on television you want to be able to keep track of exactly how long your programs are running.
The Drop Frame timecode system was devised to combat this problem. It's a way of "faking" the timecode to resync it with absolute time. The formula is fairly simple:
All :00 and :01 frames are dropped at each minute rollover, except if the minute ends in a zero.
Voila! You're back in sync with absolute time!
Either system gets the job done, and the one chosen usually depends on the application.
- If you're editing for release on video or broadcast, you usually use Drop Frame.
- If you're editing something that has been shot on film and will need to have negative conformed from your cut (i.e. you're going to have a film print made in the end), or will need to do another film-to-tape transfer for an online edit, Non-Drop Frame is used. You get more individual frame "names" out of Non-Drop Frame, and the absolute time is irrelevant.
Timecode is also used to keep track of all the tapes you're using in an edit. The "hour" portion of the timecode is usually preset to be equal to the assigned number of the tape. Of course, you can only do this for 25 tapes (if you use hour 00), but it's helpful.