Adobe Premiere Elements 8 - Manual (Page 291)

286 USING ADOBE PREMIERE ELEMENTS 8 EDITOR
Saving and sharing your movies
Last updated 8/12/2010
• Audio Interchange File Format (.aiff)
Note: Adobe Premiere Elements can import Dolby AC-3 audio in a stand-alone .ac3 file with .vob (DVD) or .mod (SD-
based camcorder) files, but it exports the audio from it as Dolby Digital Stereo only.
Note: Use Mp3 or AAC for audio-only exports for podcasts.
Compression and data-rate basics
About compression
When exporting a movie, you choose a codec to compress the information for storage and transfer (such as on a DVD),
and to decompress the information so it can be viewed again. The name “codec” comes from an abbreviation of its
function of compression and decompression. During compression, repetitive and unnecessary information in the
original file is discarded, causing the original file to lose information. For this reason, most codecs are considered lossy.
Some codecs, though lossy, still allow the file to retain a high level of quality. The DV and MPEG codecs are especially
good at maintaining excellent quality. Compressing video reduces its file size and data transfer rate, facilitating smooth
playback and reducing storage requirements. A variety of codecs are available; no single codec is the best for all
situations. For example, the best codec for compressing cartoon animation is generally not effective for compressing
live-action video. When you export from Adobe Premiere Elements, you generally only need to choose your medium
of delivery and the application will select the optimal codec for you.
If you intend for your exported movie to be played back from a hard disk or CD, make sure that the codec you use to
export your video is available to the audience for your movie. Most codecs for digital video and the web are already
available on a majority of systems. However, if you are using a codec that’s native to a particular product, make sure
that your target audience uses the same product, or can easily obtain the codec that you used.
If you intend to create a DVD or record to tape, codec compatibility is irrelevant—your audience only needs to have
the hardware necessary to play back the file.
About data rate
With some video codecs, you can specify the data rate, which controls the amount of video information that is
processed each second during playback. Specifying a data rate in
Adobe Premiere Elements sets the maximum data
rate because the actual data rate varies according to the visual content of each frame.
The data rate you specify depends on the purpose of the video. The following list describes data rate guidelines for
some uses:
DVD production The data rate should maximize quality while fitting the entire program within the space available on
the DVD. By default, Adobe Premiere Elements automatically adjusts the DVD data rate.
Non-DV videotape production The data rate should be well within the data transfer rate of your hard disk because the
video will be played back from the hard disk to the recording device. Check your documentation for information on
the data transfer rate of your hard disk.
Hard disk playback Determine the typical data transfer rate of your audience’s hard disks and set the data rate
accordingly. Generally, 7200 rpm hard disks have sustained data rates of 20 to 35 MB per second, which is high. In
comparison, the average data rate of digital video is 3.6 MB per second. So, to achieve high-quality playback, you may
not need to set the data rate as high as 20 to 35 MB per second. However, if you are exporting video for use in another
editing system or in a compositing application, such as Adobe After Effects, export at the maximum quality. Use a
lossless codec, which is one that compresses without discarding information, and specify the data rate that the editing
system supports for video capture and editing.