iMovie 6 & iDVD: The Missing Manual

12.4. The Expert Settings

The 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:

• An AVI file to give to your Windows PC-using friends . (Choose Movie to AVI .)

• A huge folder full of still images , one per frame of your movie. (Choose Movie to Image Sequence . Click Options to specify the file formatlike JPEG or Photoshopand how many stills per second you want.)

• A soundtrack . Here's a great opportunity to convert the audio tracks of your movie into standalone sound files. (Choose Sound to AIFF, Sound to Wave , or whatever format you want.)

  You'll find this feature very handy every now and then. For example, 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 GarageBand or another 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 Button

The 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 menu

The Compression Type pop-up menu at the top lets you choose one of 29 codecsor None, which means that iMovie won't compress your project at all. Each codec compresses your footage using a different scheme that entails different compromises. You can read "The Video Codecs: A Catalog" in Section 12.4.4.3 for details. For now, note that for live video that will be played on modern computers, the H.264 codec almost always produces the highest quality at reasonably small file sizes.

12.4.1.2. Quality slider

This 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 second

The 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:

• 8, 10 . These movies are very compact, and make good candidates for transmitting over the Internet. They also look very jerky.

• 12,15 . These are by far the most common frame rates for today's QuickTime movies. By playing only half as many frames as you'd see on a TV show, the QuickTime movie saves itself a lot of data, making it smaller on the disk and more likely to succeed when played on slower computers. And yet this many frames per second tricks the eye into perceiving satisfying , smooth motion; most people can sense that they aren't seeing quite the motion quality they'd see on TV, but don't miss the other fifteen frames each second.

  RARELY ASKED QUESTION 30 fps Drop-Frame

  OK, I'll bite. Why on earth did the USA, which is supposed to be so technically advanced, settle on a TV standard that plays at such an oddball frame rate? Why is it 29.97why couldn't it be rounded off to 30 ? The 29.97 frame rate, known in the TV business as 30 fps drop-frame , dates back to the dawn of color TV. As they prepared to launch color TV broadcasts in January 1954, network engineers wanted to make sure that the expensive black-and-white TV sets of the day could receive the color shows, too. (Talk about backward-compatible software!) Trouble was, when they tried to broadcast a color signal at the then-standard 30 frames per second, the extra color information wound up distorting the audio signal. Eventually, they hit upon a discovery: If they slowed down the frame rate just a hair, the distortion disappeared. The video, meanwhile, looked just as good at 29.97 frames per second as it did at 30. A standard was born.

• 24, 25 . An actual Hollywood movie plays 24 frames per second, and the European television signal (PAL) plays at 25. These settings, in other words, are provided for situations where you want excellent motion quality, without going all the way to the extreme of 29.97 frames per second of the American TV standard (NTSC). You save a little bit of disk space, while still showing as many frames as people are accustomed to seeing in motion pictures.

• 29.97 . If you're wondering how this oddball number got into the pop-up menu, you're not alone. As it turns out, every source that refers to television broadcasts as having 30 frames per second (including other chapters in this book) is rounding off the number for convenience. In fact, a true television broadcast plays at 29.97 frames per second. (iMovie can reproduce that rate for you, if it's important to do so. In fact, this is iMovie's top frame rate.)

• 30 . Don't fall for itthis choice is for suckers. NTSC (North American) digital video itself is 29.97 frames per second, so asking it to save a QuickTime movie with an even higher rate is like thinking you'll be wealthier if you exchange your dollar bills for quarters .

  FREQUENTLY ASKED QUESTION Oddly Shaped Movies

  I'm doing a project where I need my movie to be perfectly square, not in a 4:3 width-to-height ratio. But every time I try to specify these dimensions in the Expert QuickTime Settings dialog box, I get a distorted , squished iMovie movie. What can I do ? What you're really asking is how to crop your movie. Remember that iMovie creates DV movies, which have a 4:3 aspect ratio. If you want any other proportions without squishing the picture, you have to trim off some of the edges, thus cropping it. Unfortunately, neither iMovie nor QuickTime Player Pro (Chapter 14) offers any simple method of cropping the picture. There is software that can do so, however: Cleaner 6.5 (www.discreet.com), the $475 professional QuickTime-compression software. As shown here, it lets you draw a dotted -line rectangle that indicates how you'd like the picture to be cropped. If you're using iMovie for professional purposes, a program like Cleaner is a worthwhile investment. Think of it as a much more powerful and flexible version of the Expert QuickTime Settings dialog box (Figure 12-5). Its sole purpose is to compress movies, using much more efficient and intelligent software than that built into iMovie. And if you have more expertise than cash, the freeware program ffmpegX can crop video, too. You have to do it by typing in coordinates (rather than adjusting a visual cropping frame), but it works. (You can download ffmpegX from the "Missing CD" page at www.missingmanuals.com.)

  If you do try choosing 30 from this pop-up menu, when you click OK, you'll be scolded, told you're out of line, and then returned to the dialog box to make another choice.

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__frames

You 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 rate

Each 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:

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. Options

When 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, H.263, and H.264 offer far better quality, smaller size, and better compatibility.

12.4.2. The Filter Button

Chapter 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).

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 in Section 7.2.6). The trick is to create a new iMovie project containing only that clip. Export it using the DV/DVCPRO-NTSC or DV-PAL compressor (Section 12.5) 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.

12.4.3. The Size Button

And 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 Settings

At 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. Compressor

When 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:

• Linear PCM . If you're scoring at home, it stands for Pulse code modulation (PCM) with linear quantization, and it means "None." That is, Linear PCM represents an uncompressed audio filefull quality, massive size on disk, time-consuming to download from the Internet.

• ALaw 2:1 . Use this low-quality, low-compression European standard only when requested , such as when you're exporting audio-only files for people who require ALaw as an exchange format.

• AAC . If you choose this audio codec, you'll save your soundtrack in AAC formatthe same one used for songs you buy from the iTunes music store.

  Figure 12-8. It probably goes without saying that the better the audio quality you specify, the larger your QuickTime movie will be. In any case, this is the dialog box where you make such decisions. Audio isn't nearly as data-greedy as video, so compressing it isn't quite as urgent an issue (unless you want your movie to play over the Internet).

  The sound quality is superb, although it depends on the settings you make when you click Options. (Choose, for example, 128 kbits/second from the Bit Rate pop-up menu to match the quality of iTunes songs.) The file size, meanwhile, is only a fraction of the original. It's a welcome and useful choice for movies not intended to be played over the Internet.

• AMR Narrowband . This item stands for Adaptive Multi-Rate, meaning that it thins out its stream of data whenever possible (as opposed to using the same number of bits per second throughout the movie). It's intended for movies in the 3GPP format (a standard developed for cell phones).

  Use it if you have a 3GPP-compatible phone. For other phones, use the Qualcomm PureVoice codec (Section 12.4.4.2), click Options, and turn on the Half Rate option.

• Apple Lossless . This item is the only truly lossless audio compression available to you. "Lossless" means that although this codec cuts the audio track's file size in half, it doesn't lose any of the sound quality in the process. The resulting files are too big for the Web or emailing, but Apple Lossless is a great alternative to Linear PCM when you're saving a movie for best-quality playback from a hard drive.

• IMA 4:1 . This codec was one of the first QuickTime movie audio compressors. It provides excellent audio qualityyou can't change it to a sample size less than 16- bitand plays back equally well on Windows and Macintosh.

  It's great for movies that will be played from a hard drive or CD-ROM. Be aware, however, that the resulting disk-space savings aren't very great. For example, the compression isn't good enough for QuickTime movies that will be played over the Internet.

• MACE 3:1, MACE 6.1 . These options are included for people who want to swap sound files with very old Macs. They feature high compression, but very low quality. Playback works only on Macs.

• QDesign Music 2 . An engineering breakthrough , this is the sound codec to use for online or emailed movies. It maintains terrific audio quality, but compresses the sound a great deal, producing files small enough to deliver over the Internet. Apple's favorite example: One minute of music from an audio CD requires 11 MB of disk space, but after compression by this codec, it consumes only 150 K and sounds almost as good.

• Qualcomm PureVoice . The good news is that this codec compresses the audio down to almost nothing, which makes it great for transmission over the Internet or playing on a cellphone. The bad news: The quality is just barely enough to produce intelligible recordings of human speech. In other words, it isn't quite as good as telephone quality. The very low quality makes it lousy for music or anything else besides speech. (And no wonderQualcomm, who developed this codec, makes cell phones.)

• uLaw 2:1 . Like ALaw, uLaw is a common format for exchanging sound files with Unix computers.

12.4.4.2. Rate, Size

A 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.)

• 11 kHz, 8 bits . Sounds like you're hearing the audio track over a bad telephone connection. Tinny. Use it only for speech. 662 K per minute.

• 11 kHz, 16 bits . Sounds a lot better. Roughly the sound quality you get from the built-in Mac speaker. 1.3 MB per minute.

• 22 kHz, 16 bits . Starting to sound very good. Suitable for playing on a computer equipped with external speakers . 2.6 MB per minute.

• 44.1 kHz, 16 bits . This is the real thing, the ultimate audio experience. CD-quality audio. Suitable for listening to with headphones. The ultimate storage and transmission headache , toothis much data requires 5.3 MB per minute, mono. But of course, you'd never go this far without also including the stereo experience (make that 10.6 MB per minute in stereo).

12.4.4.3. Use: Mono/Stereo

These 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 Power Macs and Mac Minis, 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.