Section 15.3. Phase 1: Prepare Your Video | iMovie HD & iDVD 5: The Missing Manual

15.3. Phase 1: Prepare Your Video

For the most professional results, prepare your video in iMovie HD (or some other video-editing program) before importing it into iDVD. Here are a couple of key issues you should address before you start to build your iDVD projects.

15.3.1. Safe Colors

Standard-definition American TV sets weren't designed to display extremely bright colors. Highly saturated colors, especially red, " bleed " on most TV sets, meaning that they seem to leak out beyond their natural boundaries on the screen.

To counter this problem, you can apply a brightness limiter to your iMovie footage before using it in iDVD. Brightness limiters cut out the top and bottom 5 percent of possible illumination levels, restricting video to the middle 90 percent of available colors, thereby ensuring you won't have bleeding colors.

Note: Although this color-bleed problem is specific to NTSC video (the standard in North America and Japan), you can also apply color limit technology to PAL projects (the standard in Europe and Australia). The problem doesn't affect HDTV sets.

The results are very subtle. In fact, you might not even notice the difference unless you examine spots of bright colors in solid white zones. The "after" clips will be slightly subdued, with grayer whites and less prominent colors.

Figure 15-1. You can find a brightness limiter for iMovie in the Practical Plugins Sampler pack at www.ericasadun.com/imovie.Download a copy, unstuff the file, and double-click the .dmg file to make the disk image appear onscreen. Drag the NTSC plug-in to your Home Library iMovie Plug-ins folder. If iMovie is running, quit and reopen it. Use the Clip viewer or the Timeline to choose the clips that need adjustment. Open the Effects pane; choose the NTSC Safe Colors effect. Leave the Effect In and Effect Out sliders at the proposed 00:00 positions . Click Apply. Wait as iMovie applies the NTSC Safe Colors effect to your footage. You may want to take a break and grab some coffee as you wait.

Figure 15-1 shows how to use a safe color plug-in in movie

15.3.2. Safe Zones

Most standard-definition tube televisions overscan to compensate for the way picture tubes age over time. Overscanning TVs display only the central portion of the video picture, while clipping (hiding) the rest behind the bezel (screen frame).

In particular, broadcasters refer to two danger margins of a video image: the title-safe area and the action-safe area (see Figures 15-2 and 15-3).

Tip: Flat-panel TV sets like plasmas and LCDs don't have picture tubes, and therefore don't overscan.

15.3.3. The Title-Safe Area

When a TV chops off parts of your title, making it difficult or impossible to read, your audience can't help but notice (see Figure 15-2). As noted on page 185, you can make sure that your iMovie titles will always be safe in the resulting DVD by turning off the QT Margins box as you add titles and credits. iMovie won't allow the title to expand into the outer 10 percent on either side.

Figure 15-2. Poor planning may produce overly wide titles that extend beyond visible screen boundaries when played back on a TV. Use title-safe settings to avoid this overextended, snipped text.

15.3.4. The Action-Safe Area

Professional broadcasters also refer to the action-safe area of the screen. It's not quite as broad a margin as the title-safe area, because your audience can usually figure out what's going on even if the action is slightly clipped at the outer edges of the screen. Still, it's vital that your action remains mostly within the central portion of the screen.

Imagine, for example, a science- fiction video. A mysterious enemy teleports your hero and his sidekick to a moon of Jupiter. The sidekick throws something to the herosomething that can save the day. In Figure 15-3 at top, for example, what's in the hero's hand may be obvious to you, but most TV viewers would have a hard time guessing what it is because it's outside of the action-safe zone.

In Figure 15-3 at bottom, the sidekick's hand and the phone he throws appear completely within the action-safe zone. Even if the TV winds up chopping off the outer edges of the picture, the visual story is preserved, and your hero can safely call home.

Figure 15-3. Top: Avoid placing key visual action outside the action-safe zone of your video. Objects that appear outside the title-safe area may be cropped; objects outside the action-safe region almost certainly will be cropped by North American picture-tube TV sets.
Bottom: Although you should keep all key visual elements within the title-safe zone, you may allow nonvital portions of those elements (such as the knuckles and cord in this example) to stray into the action-safe zone.

Note: Readers and their lawyers will please forgive the science of this example, in that (a) there is no such thing as teleportation, (b) there is no air to breathe on the moons of Jupiter, let alone to talk with, (c) the hero and his colleague would die almost instantly from catastrophic depressurization, and (d) even assuming the hero could make the call out, the speed of light ensures that it would take hours for his message to reach earth. When writing computer books, authors are limited by the royalty-free art collections they have on hand. The art used here appears courtesy of Ulead's Royalty Free Media collection (www.ulead.com/pap).

You can keep your action within the action-safe area in either of two ways:

Frame correctly to begin with. Keeping important visual features and motion away from the edges of your video as you record it is by far the easiest solution.
Resize the footage. You can also buy iMovie plug-ins (see the end of Chapter 6) that resize your video and center it within the frame. This approach, however, takes a lot of time and effort, and may degrade the video quality.