Understanding Timecode

As you shoot, you're recording video to the MiniDV tape. If you ever want to find that footage again, you need to understand timecode, the method all camcorders use to label and keep track of footage. You'll use timecode constantly in iMovie, to the point where it becomes as natural as breathing.

As the tape advances, the camcorder notes where footage is being recorded and displays it in the viewfinder or on the LCD screen (Figure 2.2). A full timecode notation looks like this:

Figure 2.2. The camera assigns a timecode to each frame of film, which is used to manage your footage later in iMovie.

> 01:42:38:12 

The interpretation of those numbers is a lot like telling time on a digital clock, except for the last two digits:

> Hours:Minutes:Seconds:Frames 

So, our timecode number above is read as 1 hour, 42 minutes, 38 seconds, and 12 frames. Digital video records at 30 frames per second, so the last number starts at :00 and ends at :29.

When you're recording, you typically won't see all of those numbers. More common is something like 0:03:31 (zero hours, 3 minutes, and 31 seconds), because the camera doesn't split out partial seconds (so no frame numbers are shown). In iMovie, however, you can split clips between frames, not just between seconds, so the full number becomes important (see Chapter 8).

Keeping timecode intact

The camcorder's timecode indicator ticks away as you shoot, so in theory you can reach the end of a 60-minute tape with a timecode value of 59:59:29 (or thereabouts; I don't think I've ever actually wrapped up a tape that was exactly 60 minutes in length).

However, depending on how you've been shooting, you may notice that the timecode has started over at zero at some point. If this happens, your timecode is broken.

Before you complain to the manufacturer, look at how you were shooting. If you rewound the tape to review some footage, then started again a few seconds after the end of that clip, you inadvertently broke the timecode. The camera counts forward based on the last timecode recorded. If you move into an area of tape that hasn't been marked with a timecode, the camera doesn't know where to begin counting, and starts over at zero (Figure 2.3). Fortunately, there's a way to fix broken timecode as you're shooting but you'll record over any video recorded after the breaking point.

Figure 2.3. Broken timecode occurs when blank tape exists between sections of footage. The camcorder uses the last known timecode marker (in this example, 04:15) to compute the time for later frames. However, the portion of blank tape before the new footage has reset the timecode back to zero (00:00).

To fix broken timecode:

1. With your camera in Play (VCR) mode, rewind the tape until you see the last footage with unbroken timecode.

2. Advance the tape until you're about two seconds from the end of that footage.

3. Switch the camcorder to Camera mode and begin recording from that point.

I Broke It. So What?

It's not essential that you maintain unbroken timecode throughout your video. Such breaks aren't going to damage your footage, or even confuse iMovie. They will make it more difficult for you to go back and locate specific scenes that you've shot, however. It's far easier to insert your tape and advance to 0:27:18 than to remember that your scene is at 0:02:24 somewhere in the middle of the tape.

Tips

• iMovie doesn't use timecode to work with the tape in your camera. Most high-end video editing packages let you specify a timecode value and then the program advances or rewinds the tape to that point. In iMovie, that task is up to you. If you have unbroken timecode on your tape, it's a lot easier for you to find the footage you're looking for without having to review every minute.

• Maintaining unbroken timecode means less wear and tear on your camera. When you search by reviewing your footage, the tape is in contact with the playhead inside the camera. A camcorder's life span is based on the number of hours the playhead is used, so repeatedly scanning the video using the fast-forward and rewind features while it's playing contributes to the wear of the playhead. Instead, forward or rewind the cassette without playing it, when the tape is not in contact with the playhead. This doesn't mean you're going to kill the camera by viewing your footage, just that you are helping to speed the process a little.

iMovie Timecode versus Real-World Timecode

Video purists may bristle when I talk about timecode in iMovie, because the concept of timecode in iMovie is a bit different from the timecode used in the industry at large.

For the sake of simplicity, say you import a 5-minute clip into iMovie that appeared halfway through your MiniDV tape, or roughly 00:30:00:00 (zero hours, 30 minutes). When you select that clip in the Shelf, its timecode begins at 00:00:00:00 and ends at 00:05:00:00 (I'm using full-length timecode notation for this example; in iMovie, it appears as 05:00).

In professional editing programs like Final Cut Pro, the timecode for that clip would begin at 00:30:00:00 and end at 00:35:00:00 to reflect precisely where on the tape the clip originates. This is important if the editor needs to recapture an exact section of footage.

However, iMovie was designed for people who don't necessarily need to know exact timecode, which is why iMovie timecode remains relative to the length of the clip.