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From iMovie to QuickTime > From iMovie to QuickTime - Pg. 308

The Video Codecs: A Catalog So what good is it? Motion JPEG is the format used by many professional DV-edit- ing machines (such as those from Avid, Accom, and Discreet). Because there's no key-frame business going on, editors can make cuts at any frame. (Doing so isn't always possible in a fle created by a codec that stores only the difference between one frame and the next. A particular frame might contain data that describes only new information, as shown in Figure 12-4.) Tip: Motion JPEG is not the same thing as MPEG, which is the format used to store movies on the DVD discs you can rent from Blockbuster. Despite the similarity of names, the differences are enormous. For example, MPEG uses temporal compression and requires special software to create. ·None. If quality is everything to you, and disk space and Internet-ability are nothing, you can use this option, which (like the DV codecs) doesn't compress the video at all. The resulting QuickTime fle may contain so much data that your computer can't even play it back smoothly. You can, however, put it in a cryogenic tank in anticipation of the day when superfast computers come your way. ·PlanarRGB. This format is another one that's designed for use with still images, not with video. This one preserves the alpha channel of the graphic (a transparency POWER USERS' CLINIC