Timecode and control-track breaks, where the smooth progression of frame numbers on a tape is broken and often reset to 00:00:00:00, have been the bane of video editors ever since tape machines were invented. Many an editor has cursed many a cameraperson for their failure to keep good consistent timecode on their tapes. This cursing has not stopped with the widespread use of nonlinear editing systems. Tapes are still being brought into edit rooms with breaks or discontinuities in timecode.
Any cameraperson who delivers a tape with timecode breaks caused by negligence or incompetence is unprofessional. Camera problems are a different matter. All professional cameras, and these days, every consumer and prosumer cameras, are designed to generate frame-accurate timecode, and that’s the way tape should be delivered.
With DV cameras, a number of methods will ensure that there are no breaks in your tape’s DV timecode. The simplest method, one that I recommend for beginners and students, is to prestripe your tapes by recording black and timecode on your tape before you shoot. You can do this in any camera or VCR by inserting a tape, simply putting the device in VCR mode, and pressing the record button. If your camera needs to be in camera mode, just put a lens cap on the camera and press record.
Now whenever you shoot your tape will have timecode written on it. The camera will then read the timecode and start writing from whatever it reads. No breaks.
Prestriping is not a good idea for all professional cameras. Many professional cameras using Record Run timecode must have the Return Video button pressed for the camera to seek the end of the written timecode. If the cameraperson doesn’t do this you will get discontinuities—numbers that skip time—that are almost as bad as breaks that reset timecode to zero.
Any timecode break is liable to cause a sudden loss of AV sync when you capture a clip with its In and Out points on two sides of a break. If you do have a tape with timecode breaks in it, one of the simplest ways around the problem is to dub the tape.
In DV there is no quality loss when dubbing across FireWire. The audio and video are copied exactly from one machine across a FireWire cable to another. As it copies the tape, the recording deck generates new clean, continuous timecode, with no breaks. Unfortunately, if you do copy the tape like this, the one that isn’t cloned with it is the metadata that carries the clock time, so you’ll no longer be able to use DV Start/Stop Detection.
Copyright © 2002 South Coast Productions