Adobe ENCORE 2 Manual page 30

ADOBE ENCORE DVD 2.0 25
User Guide
About free/used space information
The Disc panel displays the available space and the used space for the specified disc size during the authoring
process. The display conveys size information only and has no bearing on quality. Adobe Encore DVD calculates the
free space using the transcoding data rate (whether it was set automatically or manually). It then combines this
estimated bit rate with the actual bit rate of any transcoded clips and, based on the disc size, calculates the space
remaining on your disc.
When transcoding assets, Adobe Encore DVD attempts to maintain the highest quality (highest data rate) for the
amount of video in the project. If you continue to add video to a project, the program lowers the video data rate to
squeeze in the additional content. Adobe Encore DVD will warn you if quality dips below a certain level once you
build the project or run Check Project. For more information, see "About transcoding" on page 28.
To check the space remaining on your disc
❖
Click the Disc tab to display the Disc panel. The disc graphic shows the space used and space remaining.
Asset types and amounts
Of all the content types, the video portion of a DVD occupies the most disc space. Depending on the data rate, one
minute of video can occupy anywhere from 180 to 588 MB. One minute of compressed audio, on the other hand,
occupies only 11.5 MB. Still menus are negligible in terms of size. (See "Average asset size" on page 27.)
The amount of video in a project directly affects the optimal data rate. You need an accurate tally of the amount of
video in a project to develop a bit budget and to choose a disc size. If the project contains one hour of video, for
example, it can be transcoded at twice the data rate as a project with two hours of video content. Although the video
content in each project occupies the same amount of disc space, the quality of the hour-long video will be superior
(though not necessarily by a factor of 2).
See also
"About transcoding" on page 28
Data rates
Data rates, usually expressed in Mbps (megabits per second, or 1,000,000 bits/sec), specify the amount of data
contained in an asset stream and directly affect the quality of video. The data rate is used during transcoding to
compress the asset. For video assets, the Adobe Encore DVD transcode presets use data rates ranging from 4 to 9
Mbps. You can edit the presets' data rates, but you cannot exceed 9.0 Mbps, nor can you go below the Adobe Encore
DVD minimum data rate of 2.0 Mbps. Typical data rates for video range between 4 and 6 Mbps. If bit budgeting
targets a data rate less than 6 Mbps, you should consider using variable bit rate (VBR) encoding. For more infor-
mation about VBR, see "To calculate a bit budget" on page 26. For more information about transcoding, see "About
transcoding" on page 28.
While data rates are a general indicator of quality, there are no hard-and-fast rules to equate data rate to quality. That
is, a data rate of 4 Mbps may or may not produce a high-quality asset—quality depends on the image data and type
of compression used as well as data rate. For example, video of a seated person shot against a solid background can
probably be compressed to a lower data rate than a fast-paced car chase with constantly changing visuals, with no
noticeable differences in quality.