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Audio Settings > Audio Settings - Pg. 303

iMovie will have to squish the picture accordingly, which may lend a funhouse-mirror distortion effect to your flm. 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. The Expert Settings 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 how--and how much--your soundtrack is compressed in the exported QuickTime movie (see Figure 12-8). Compressor When most people think of codecs--those who've even heard of codecs, that is--they 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 fles as it is at creating movies. For best results in most movies, use the QDesign or IMA setting. For the beneft of trivia fans, here's the complete list: ·24-bitInteger,32-bitFloatingPoint,32-bitInteger,64-bitFloatingPoint. If you don't already know what these are, then you're not a hardware or software engineer who traffcs in this kind of audio fle. These formats are high-quality, no-compres- sion fle formats that aren't appropriate for movie soundtracks. ·ALaw2:1.Use this low-quality, low-compression European standard only when requested, such as when you're exporting audio-only fles for people who require ALaw as an exchange format. ·AMRNarrowband.This item, which debuted in QuickTime 6.3, stands for Adap- tive 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 (page 304), click Options, and turn on the Half Rate option. ·AppleLossless.This item, also part of QuickTime 6.3 and later, is the only truly lossless audio codec available to you. "Lossless" means that although this codec cuts the audio track's fle size in half, it doesn't lose any of the sound quality in the process. The resulting fles are too big for the Web or emailing, but Apple Lossless is a great alternative to "None" when you're saving a movie for best-quality playback from a hard drive. ·IMA4:1. This codec was one of the frst QuickTime movie audio compressors. It provides excellent audio quality--you can't change it to a sample size less than 16-bit--and plays back equally well on Windows and Macintosh. chapter12:fromimovietoquicktime 303