Once you have created your content, you can compress it in the following ways:
In some applications (such as QuickTime Pro and iMovie HD), you can compress the file when you export it.
You can import an uncompressed file into iTunes and then compress it.
You can compress several files at once using a range of tools that do batch processing, such as Compressor, included with Final Cut Studio.
To compress a file using iTunes, make sure the file you want to compress is in the iTunes Library. To import the file into the iTunes Library, choose File > Import. Find and select the audio or video file to compress in the iTunes Library. To compress an audio file, choose Advanced > “Convert Selection to AAC” (requires iTunes importing preferences to be set to AAC). To compress a video, select the file within your iTunes library and choose Advanced > “Convert Selection for iPod”.
Note: If the file is already compressed, you should not re-compress it—that will lower the quality. You can tell if a file is already compressed by selecting the file in the iTunes Library, then choosing File > Get Info. In the Get Info Summary pane, compressed files will display the Kind as AAC or MP3 audio for audio files and MPEG-4 for video files.
© 2009 Apple Inc. All Rights Reserved. (Last updated: 2009-11-04)