Short Video Editing Encyclopedia

Imagine sitting in a small, family restaurant in the heart of Italy. You pick up the menu and see an array of words that make no sense to you. Your waiter comes by and patiently tries to help you but to no avail. No one understands you and your vain attempts to express yourself fail miserably. It's all a matter of communication.
Well, linear editing systems rely on communication in much the same way we do. Each system uses a distinctive language, called an editing protocol, that enables it to talk between its editing decks and its edit controller. If the editing decks or camcorders speak a different language than the edit controller does, they won't be able to understand one another and you will become incredibly frustrated.
The names of the various editing protocols are reminiscent of a confusing alphabet soup: RS-422, RS-232, Control-S, Control-L, Control-M, IR and the most recent addition to the alphabet, IEEE 1394. If you've ever tried to edit on a system made up of equipment from different manufacturers, you can understand the frustration. It's like trying to talk to someone from Mexico, France and Russia all at the same time. To avoid this, it's important to understand what editing protocols do, the various levels of sophistication and how to get a camcorder or editing deck to communicate to a foreign edit controller.

Editing protocols are nothing more than a means by which a piece of equipment sends and receives data (time code, in/out points) and various commands (record/stop/play) to and from other equipment. Camcorders and edit decks need a specific editing protocol to "talk" to edit controllers, switchers and titlers. These pieces of equipment need to be able to tell each other when to pause, rewind, fast forward and record. Prerolling tapes is a great example of how these machines talk to each other by means of an editing protocol.
After you've set your edit points and you're ready to edit, the edit controller uses an editing protocol to tell the decks to rewind the tape five seconds before your in point. It then rolls the tape forward to the edit. If you have to do this manually, it's a real pain and not too accurate. With an edit controller, you can set up a series of commands for the editing system to execute. The edit controller then stores these functions in its memory. Taking advantage of an edit controller, you can:

• Set your exact in and out points on both your source tape as well as your record tape.
• Set a trigger point and duration for a fancy transition or title when using your editor with a special effects generator or character generator.
• Trigger your devices at precise points by reading the time code on your tapes. The edit controller's memory and the use of a specific protocol also enable the editor to send a series of commands and have the machines execute all of them accurately. In the old days, before edit controllers with edit protocols existed, it wasn't uncommon to have to edit using a variety of fingers, elbows and some rather athletic moves to create a basic A/B roll edit between two sources, a switcher, character generator and an edit recorder.

As we listed already, there are many edit protocols with confusing names. Each has its own level of sophistication, editing language, connector and connection style and accuracy limitations. Very few of them are compatible. As you read this article, keep in mind your budget, production requirements in terms of accuracy and format and current equipment.

The infrared remote protocol, or IR for short, is the least sophisticated of the true edit protocols. You actually use an IR protocol every time you change channels on your TV using an infrared remote. Like the TV remote at home, this protocol provides only one-way communication (see Figure 1). The infrared emitter sends a signal to your editing deck or camcorder and tells it to fast forward, rewind, pause, change audio modes between linear and Hi-fi, reset the counter, stop and eject the tape. No information goes back to the infrared device, so it has no idea if the command is accepted or how far the VCR has shuttled the tape. You're responsible for that part of the communication. The infrared remote protocol, because it communicates only one way, can't read your tape's time code or control pulses, either, so your edits with this type of protocol are very "loose" or imprecise.
This type of editing protocol also requires you to precisely position the infrared emitter so that the equipment you are trying to control can pick up the signal (see Figure 2). If you move the IR controller out of position, you won't be able to send the edit commands to the devices.