Section 11.3. Notes on DV Tapes | iMovie 6 & iDVD: The Missing Manual

11.3. Notes on DV Tapes

As noted in Chapter 1, DV cassettes present the promise of immortality for your video. Because you can transfer the footage nearly indefinitely from camcorder to computer (or to camcorder) without ever losing quality, there's no reason your footage can't stick around forever.

The tapes themselves are not immortal, however. Although you can record and rerecord them dozens of times, you can't do so indefinitely, as most people assume. You'll know when a particular cassette is starting to go when you begin to notice dropouts in the videopops in the picture, tiny rectangular pixels of the wrong color . At that point, it's time to retire that cassette.

Tip: Follow the advice on the little set of label stickers that comes in each tiny DV cassette box. Keep the tapes in their boxes, away from dust, heat, magnets, electricity, marauding children, and so on.

11.3.1. The Two-Cassette System

Consider conceiving of each iMovie project as a two-cassette affair. Designate one cassette (or set of cassettes) as your raw-footage tapes, and a second set as the finished-movie tapes. (Video editors call these the original and master tapes, respectively.)

Doing so, and labeling the tapes carefully , makes it less likely that you'll accidentally record over some important movie that you slaved at for days. It also makes life simpler when friends come over and suddenly say, "Hey, let's see what you did with your Mac!" If you keep all of your iMovie creations on a single special cassette, you won't have to hunt for a particular tape to show them your prize-winning creations.

11.3.2. Labeling and Logging

DV cassettes are so tiny that you'll find it almost impossible to write more than a few words onto their little white labels. If you want to write more, you'll have to use the fold-out cardboard index card that comes inside the cassette's little plastic box.

Tip: As noted earlier, it's a good idea to label your DV cassettes before you record them, especially if you'll be filming an event that requires multiple tapes (such as weddings or shows). Your annotation doesn't have to be elaborate ( 1, 2, 3 , and so on is fine), just something to prevent you from shoving an already-recorded cassette into the camcorder, forgetting , in the heat of the moment, that it's not a blank.

While shooting, professional film and video makers keep careful track of which cassette contains which shots, and which takes of those shots were useful. In fact, they typically write "G" ( good ) or "NG" ( no good ) on the log sheet as they complete each shot.

This kind of logging can save you lots of time when you sit down to transfer the footage from camcorder to Mac, because you don't have to sit there watching the entire hour of tape. You already know that the first 15 minutes were fantastic, followed by 15 minutes of lousy stuff that you can fast-forward past, and so on.

11.3.3. Long Play Mode

Most DV camcorders let you squeeze 90 minutes onto each 60-minute cassette by using Long Play ( LP) mode, in which the tape travels more slowly through the camcorder. On a DV camcorder, LP mode doesn't bear the same stigma of lousy picture quality that it does on VHS equipment. In fact, there's no difference in quality between LP and Standard Play mode. The data is stored as a stream of numbers ; the computer doesn't care how fast they're slipping through the camcorder innards.

You should, however, be aware of several LP side effects. For example, you lose the ability to dub in a second soundtrack after having recorded some video. That's not much of a sacrifice, however, since you can do the same thing and more in iMovie. In theory, LP mode also increases the chance of getting dropouts.

Avoid recording LP and standard-speed footage on the same cassette; in fact, for best results, use LP-recorded tapes only in the camcorder that recorded them. Swapping LP tapes among different camcorder modelsor even different units in the same camcorder lineinvites dropouts and other video noise, because the playback heads in each camcorder are aligned differently. LP recordings use a much narrower stripe of tape to record video information (6.7 microns wide, instead of 10 microns wide in Standard Play mode), so even minor differences in the position of the heads in different camcorders can result in LP playback problems.

Clearly, LP recording is something of a black art. For the smoothest sailing in your DV career, avoid it except when getting 90 minutes on a tape is crucial to your project.

11.3.4. The Protect-Tape Tab

In the old days of audiocassettes and VHS tapes, you could prevent an important recording from being accidentally erased by a clueless family member. You simply had to pry out or break off a tiny, plastic, square "protect" tab on the top edge of the cassette. Doing so left a hole that prevented the recorder from recording.

The trouble with that system, of course, was if you changed your mind, the only way you could "unlock" the tape to permit recording again was to cover the little hole with a piece of tape. This tape trick was an inelegant solution, and often a risky one, because tape peeling off inside a VCR was a one-way ticket to the repair shop.

DV and Hi-8 cassettes (for Digital8 fans) are far more sophisticated. They have a sliding shutter that covers the "can't record" hole (see Figure 11-4), making it much easier to prevent recording on a particular tape and then change your mind.

Note: The record-lock tab on Digital8 (Hi-8) tapes works backwards from mini-DV cassettes. The little red slider covers the hole to prevent recording, and must be open to record.

Figure 11-4. You need a sharp fingernail, pocket knife blade , or other implement to slide this very small shutter (top right). But at least you'll never need tape to cover the hole.