12.4. The Expert SettingsThe canned presets aren't the only ways you can turn your iMovie project into a QuickTime movie. By choosing Expert Settings from the pop-up menu shown in Figure 12-1, and then clicking the Share button, you embark on a tour of crazy nested dialog boxes. Along the way, you'll be offered control of every aspect of the compression process, including which codec it uses, the degree of sound compression, how many frames per second you want, and so on. The first dialog box to appear is the "Save exported file as" box, where you can type a name and choose a folder location for the file you're about to save (Figure 12-5, top). Resist the temptation , for now. The real power lies in the buttons and pop-up menus elsewhere in this little box. For starters, the Export pop-up menu (shown at top in Figure 12-5) offers a wealth of conversion options. This is your opportunity to save your film as:
You'll find this feature very handy in two situations. First, you can use iMovie as a quick-and-dirty piece of sound-recording software (see Chapter 8), and use this feature to export the recording as a sound file. Second, certain troubleshooting situations, described in Chapter 8 and elsewhere, call for your exporting and reimporting your finished soundtrackin essence, temporarily splitting it apart from the video. (You can even edit the soundtrack file in a sound-editing program along the way, if you're so inclined. That's one way to get rid of the occasional pop or crackle.)
But most of the time, you'll ignore this Export pop-up menu. Most of the time, you'll want to leave it set to "Movie to QuickTime Movie," and then click the Options button to make some settings changes. As illustrated in Figure 12-5, that Options button opens a very important dialog box: the Movie Settings box. Here's where you can export your finished product with exactly the size-smoothness-speed compromise you want. You'll notice that this box offers three buttons for video: Settings, Filter, and Size. Below that, you get one Settings button for Sound; and at the bottom of the box, you get options for Internet streaming. All of these settings are covered in the next few pages. 12.4.1. The Settings ButtonThe Settings button takes you to the powerful Compression Settings dialog box (Figure 12-6), the heart of the entire Expert software suite. Here's what the controls do:
12.4.1.1 Compressor pop-up menuThe unlabeled pop-up menu at the top lets you choose one of 27 codecsor None, which means that iMovie won't compress your project at all. Each codec is useful in a different situation; each compresses your footage using a different scheme that entails different compromises. You can read "The Video Codecs: A Catalog" on page 305 to learn about the codecs listed in this pop-up menu. For now, it's enough to note that for live video that will be played on modern computers, the Sorenson Video 3 codec almost always produces the highest quality at reasonably small file sizes. 12.4.1.2 Quality sliderThis slider offers another tradeoff between the size of the resulting QuickTime file and the quality of its picture. In general, the proposed value (usually Medium or High) offers the best balance between file size and picture quality. But on important projects, by all means experiment. Export a representative sample of your movie several times, moving the slider each time, so that you can compare the results. 12.4.1.3 Frames per secondThe number you specify here makes an enormous difference in the smoothness of the QuickTime movie's playback. As always, however, it's a tradeoffthe higher the number, the larger the QuickTime file, and the more difficult it is to email, store, or transfer. You can type any number between 1 and 29.97 in this box, or you can use the pop-up menu to the right of the "Frames per second" box. Here's what you can expect from these settings:
As described under "Quality slider" in the previous section, you don't have to export your movie in its entirety, just to see the effects of different frame-rate settings. Create a dummy project that contains only a few seconds of your movie, and try exporting it at each frame rate. Then play back the short QuickTime movies. You'll get a self-instruction course in the effects of different frames-per-second settings. 12.4.1.4 Key frame every __ framesYou can read about key frames earlier this chapterthey're the full frames that get "memorized" in your QuickTime movie, so that the QuickTime file can store less data for subsequent frames (see Figure 12-4). Additional key frames make your QuickTime file bigger, so you have an incentive to make them appear infrequently (that is, to type in a higher number in this box). But if the resulting QuickTime movie is something that your viewers might want to skip around in, key frames are very useful. Somebody might scroll back into the movie to a spot with no key frame. When playback begins at that point, the image might be scrambled for a fraction of a second, until the next key frame appears. In most cases, one key frame per second is about right. In movies that will be played back from beginning to end and never rewound or scrolled, it's safe to increase the number in this box. 12.4.1.5 Limit data rateEach delivery mechanisma CD-ROM, a cable modem, a 56 K modem, and so ondelivers information at a different rate. If you want to ensure that no frame-skipping or jerkiness occurs when somebody plays your movie, turn this checkbox on and type a number into the box. The precise number to type depends on your goals for the movie you're exporting. In other words, it depends on what kind of gadget will be playing the movie data. Here are some guidelines for the Sorenson codec: Table 12-1.
iMovie automatically adjusts the picture quality as necessary, on a moment-by-moment basis, so that the QuickTime movie will never exceed this rate. 12.4.1.6 OptionsWhen you choose the names of certain codecs from the Compressor pop-up menuMotion JPEG, Photo-JPEG , PNG, Sorenson Video, or TIFF, to be precisean Options button magically appears in the dialog box shown in Figure 12-6, top. In general, you can ignore this button and the extremely technical dialog box that appears when you click it. The "options" for the Sorenson codec aren't options at allonly a summary of your settings. And the options that appear for the other codecs offer only one useful option"Optimize for Streaming." You'd use this checkbox if you intended to prepare your movie for streaming Internet video, as described in the next chapter. Trouble is, you'd be foolish to use the JPEG, PNG, or TIFF codecs for this purpose to begin with. Codecs like Sorenson and H.263 offer far better quality, smaller size, and better compatibility. 12.4.2. The Filter ButtonChapter 6 details a number of special effects you can apply to clips in iMovie. But unbeknownst to nine out of ten iMovie fans, you can apply a second suite of special effects to your movie on its way out of iMovie. Simply click the Filter button (Figure 12-5) as you export a QuickTime movie. The dialog box shown in Figure 12-7 appears. By opening the various flippy triangles , you'll find a lot of effects you've seen before in iMovie (color balance, brightness and contrast, lens flare, fake old-film grain)and a few you haven't (blur or sharpen, emboss, edge detection).
The list of effects appears in the scrolling list at top left; a preview of the result appears in lower left. Use the controls on the right side of the dialog box to affect the intensity and other settings of the effect. As you work, remember that whatever filter you apply here applies to the entire movie you're about to export. You might be inclined to pooh-pooh this whole feature, in that case. Really, when would you ever want to apply the same degree of blur to an entire movie? But with a little forethought, you can still apply an effect to just one clip (or one section of your movie, using the invisible-title trick described on page 195). The trick is to create a new iMovie project containing only that clip. Export it using the DV/DVCPRO-NTSC or DV-PAL compressor (page 307) to make sure that you retain all your digital-video size and qualityand apply the filter you want in the process. When it's all over, you can reimport your exported, processed clip into the original iMovie file. CAUTION iMovie preserves your Expert settings from export to export, even if weeks or months elapse in between. That's an especially treacherous feature when it comes to these filters; you may sit through a 45 minute export the next time, only to find that the resulting movie is all Embossed and color-shifted because those are the settings you used last time. The only way to escape this nightmare is to reopen the Filter dialog box and choose None. 12.4.3. The Size ButtonAnd now, back to your tour of the dialog box shown in Figure 12-5. The Size button summons the dialog box shown at bottom in Figure 12-6, whereafter clicking "Use custom size"you can specify the dimensions for the playback window of your QuickTime movie. See Figure 12-3 for some examples of these different sizes. Of course, the larger the window you specify, the longer the movie will take to save, the slower it will be transmitted over the Internet, and the larger the resulting file will be. Keeping the dimensions you specify here in a width-to-height ratio of 4:3 is important. (In the business, they call the width-to-height ratio the aspect ratio of the picture.) The QuickTime software plays back most smoothly if your movie retains these relative proportions. Furthermore, if the width and height you specify aren't in a 4:3 ratio, iMovie will have to squish the picture accordingly , which may lend a funhouse-mirror distortion effect to your film.
The huge majority of QuickTime movies play in at one of several standard sizes, such as 160 x 120, 240 x 180, or 320 x 240. All of them maintain this 4:3 aspect ratio. Still, there are dozens of other possible sizes that maintain the correct proportions. 12.4.4. Audio SettingsAt the bottom of the dialog box shown in Figure 12-5 is a second button called Settings. This one lets you specify howand how muchyour soundtrack is compressed in the exported QuickTime movie (see Figure 12-8). 12.4.4.1 CompressorWhen most people think of codecsthose who've even heard of codecs, that isthey think of video compression. But iMovie offers a choice of audio codecs, too. This pop-up menu lets you specify which one you want to use. Many of them aren't, in fact, appropriate for movie soundtracks . Remember that these codecs are provided by QuickTime, not by iMovie, and that QuickTime is designed to be an all-purpose multimedia format. It's supposed to be just as good at creating pictureless sound files as it is at creating movies. For best results in most movies, use the QDesign or IMA setting. For the benefit of trivia fans, here's the complete list:
12.4.4.2 Rate, SizeA computer captures and plays back sound by capturing thousands of individual slices, or snapshots, of sound per second. As though describing somebody at a wine tasting, computer nerds call this process sampling the sound. The two controls here let you specify how many samples you want the Mac to take per second (the sampling Rate) and how much data it's allowed to use to describe each sample (the sampling Size). Even if that technical explanation means nothing to you, the principle is easy enough to absorb : The higher the Rate and Size settings (see Figure 12-8), the better the quality of the audio and the larger the size of the resulting QuickTime file. Here are a few examples of the kind of file-size increase you can expect for each of several popular rate and size settings. (Note that the information here is per channel. If you're going for stereo, double the kilobyte ratings shown here.)
12.4.4.3 Use: Mono/StereoThese radio buttons let you specify whether or not your movie's soundtrack is in stereo. As noted earlier in this chapter, exporting your QuickTime movie with a stereo format is often a waste of data. Most computers that might play back your movie, including tower Power Macs and iBooks, don't have stereo speakers. Furthermore, even though most camcorders include a stereo microphone, there's virtually no separation between the right and left channels, thanks to the fact that the microphone is mounted directly on the tiny camcorder. Nor does iMovie let you edit the right and left audio channels independently. Even if people are listening to your movie with stereo speakers, they'll hear essentially the same thing out of each. Therefore, consider using the Mono setting when you're trying to minimize the amount of data required to play back the soundtrack. |