ADOBE PREMIERE PRO 2.0
User Guide
375
About data rate
With some video codecs, you can specify the
data rate
, which controls the amount of video information that must
be processed each second during playback. Specifying a data rate actually sets the maximum data rate, because the
actual data rate varies depending on the visual content of each frame.
To maximize the quality of encoded video, set the data rate as high as the target delivery medium can support. If you
plan to stream video to an audience using dial-up Internet access, this may be as low as 20 kilobits per second;
however, if you plan to distribute video on DVD, it may be as high as 7 megabits per second.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. In Adobe Premiere Pro, the DVD data rate is automatically adjusted by the Adobe Media Encoder when
you choose File > Export > Export To DVD.
Non-DV videotape production
The data rate should fall within the capabilities of the computer and hard disk that
perform the final playback to tape.
Hard-disk playback
If the final video will be played back from a hard disk, determine the typical data transfer rate
of your audience’s hard disks and set the data rate accordingly. If you are exporting video to be used in another editing
system or to be imported into a compositing application, you’ll want to export at the maximum quality. Use a lossless
codec or the codec supported by your video capture card, and specify the data rate that the editing system supports
for video capture and editing.
CD-ROM playback
The data rate for video played from a CD-ROM depends on the speed of the drive. For example,
if you are preparing a final video file for a quad-speed CD-ROM drive (600 kilobytes per second), you might specify
between 300 and 500 kilobytes per second to account for both the data rate of the drive and for the system overhead
required to move the data.
Intranet playback
The data rate can be 1 megabit per second or faster, depending on the speed of your intranet.
Because they are limited in scope, intranets generally use higher quality communications lines than standard
telephone lines, so they are usually much faster than the Internet.
Streaming video over the web
The data rate should account for real-world performance at the target data rate. For
example, the data rate for streaming video designed for a 56-kilobit-per-second connection is often set to 40 kilobits
per second. That’s because factors such as data volume and line quality often prevent telephone-based Internet
connections from consistently achieving their stated data rate. For broadband connections, set the data rate for
streaming video to 128 kilobits per second.
Downloading a video file over the web
The data rate is less important than the size of the video file on disk, because
the main concern is how long it takes to download the file. However, it still may be desirable to reduce the data rate
for downloaded video because doing so reduces the size of the video file, making it download faster.
If you use Adobe Premiere Pro, use the Get Properties For command to analyze the data rate of files you export.
Exporting to videotape or DVD
Exporting to videotape
You can record your edited sequence onto videotape directly from your computer. The format and quality of the
video depends on the Editing Mode you specified in the Project Settings dialog box.