Even though all types of time code appear the same on the display panel (00:00:00:00), they differ in the way they are recorded onto videotape.

You can insert time code directly into the video signal itself, in an invisible part of the video signal known as the vertical interval. This vertical-interval time code (VITC) must be recorded at the same time as the picture. And you can't copy VITC time code directly from one tape to another. To copy VITC, you must send the video signal through a regenerator. The regenerator outputs a clean, new VITC signal, which you can then record to a new tape.

Longitudinal time code, on the other hand, is a separate signal that you can record onto a separate linear track that runs along the length of the tape. The best-known type of linear time code is SMPTE (developed by the Society for Motion Picture and Television Engineers). You can record SMPTE onto the monaural linear audio track on a VHS or S-VHS tape, but not onto the hi-fi track.

Not to be outdone, Sony developed two proprietary types of time code: rewriteable consumer time code (RCTC) for consumer 8mm/Hi8 equipment, and industrial 8mm time code for industrial/professional 8mm/Hi8 equipment. Sony set aside a particular sector of the tape to hold either of these types of time code without disturbing the video or audio signals. RCTC and 8mm time code are not compatible with each other. The main difference between them is that industrial 8mm time code is guaranteed to be frame accurate; RCTC is not. Officially, RCTC is accurate to within +/- 2 to 5 frames, though half the time it's right on the money.

If you do all of your production in-house using your own equipment, then you should be able to pick a particular time-code system and buy gear that's compatible with that kind of time code. But if you shoot your own footage and take it to a service bureau to edit it, you could run into trouble if the service bureau uses a different time-code system. There's a question that's worth a phone call.

Time code not only affords accurate edits, it can also help you protect your precious original footage.

If you use your original video footage for editing, all that jogging back and forth to find and log scenes can put lots of wear and tear on the tape. Instead of risking the quality of your original footage, you can create what's called a "window dub" for review. To create a window dub, you play back the original footage while a time-code reader superimposes the numbers onto the screen. When you record this onto another tape, it shows all of your footage with the time code numbers "burned-in" on top of it. (If you're using a service bureau for your editing, ask if they can make a window dub using your type of time code.) The window dub is not useful for final product (you can't get rid of the numbers once they are burned-in), so you can treat it with contempt. Shuttle back and forth until the tape is as thin as tissue, it doesn't matter--it's only a window dub. Your original stays in the box, pristine and unscathed, until it's time for the final edit.

Preparing for a complicated edit session is easy with time code. All you need to do is make a list of which scenes you want to keep and which scenes, figuratively speaking, end up on the cutting-room floor.

View your window dub until you see the shot you like and pause the tape where you want the edit to begin. Write down the numbers that appear on the screen. Now let the tape run until you find the end of the shot. Write down this new set of numbers. Put a brief description of the shot next to the numbers. Do this for every "keeper" scene and you've made an EDL.

Maybe you have editing software or a stand-alone edit controller that can read time code. If so, you can perform the process this way: run the tape until you find the shot. Punch a button that saves the time-code number into the computer memory. Find the end of the shot and punch a button to save the end time. If you're using a computer-based logger, you might be able to type in a description of the shot, or even save a small graphical image from the video (a "picon") to identify the clip visually.

Whatever method you use to log your footage, the logging step can save you time and money if you plan to edit at a service bureau. If the clock is ticking (and you are paying for each tick), you don't want to waste this time searching for footage.

Once you've logged all your shots, you have the main ingredients to cook up an edit-decision list (EDL). With a paper EDL, you arrange your shots in the order that you want them in the final edited show. If you take all of your raw footage to a service bureau and give these numbers to the person who is pushing the buttons, you can get through the session in the smallest amount of time.

If you have a system that can save time-code numbers as you create your EDL (such as a computer-based system), you may be able to save the electronic EDL on a floppy disk and hand this EDL to the service bureau. If the bureau's equipment is compatible, they can feed the EDL into the their equipment and assemble the show automatically. Of course, you will still want to add titles, sound effects, music and so on, but an EDL can still save a lot of time.