Apple DVD Studio Pro 4 - Manual (Page 58)

16:9 and SD Projects
The DVD specification and DVD Studio Pro require 16:9 video to be anamorphic. An
anamorphic 16:9 video frame has the same number of pixels as a 4:3 video frame. When
displayed on a 16:9 monitor, the frame is horizontally stretched to fit the screen, and the
content appears normal. When viewed on a 4:3 monitor, however, the video content
appears horizontally compressed (see the illustrations in
Choosing an Aspect Ratio ).
The most common error is to letterbox your 16:9 video assets before bringing them into
DVD Studio Pro. Once a 16:9 asset has been letterboxed, it becomes a 4:3 asset with black
bars along the top and bottom of the video image. If you flag letterboxed source video
as 16:9 video when encoding it, you will have problems when you play it back later.
16:9 and HD Projects
HD projects can use a wide variety of video resolutions. Several of these are true 16:9
(1280 x 720p and 1920 x 1080i) while several others use the same anamorphic method
used in SD projects (720 x 480p, 720 x 576p, and 1440 x 1080i).
Using Pan-Scan to Display 16:9 Video
The pan-scan method of displaying 16:9 video on a 4:3 monitor was developed as a
compromise between letterbox, which displays all the video content but with black areas
at the top and bottom, and the only other alternative: filling the entire 4:3 screen, but
cropping some of the content. With pan-scan, you can choose which bits of the 16:9
content to crop, ensuring the action is not lost by displaying the center of the screen
only. The pan-scan method can result in sudden jumps from one side of the screen to
the other (for example, to follow a conversation’s dialogue), which may make your video
look as if edits have been made.
To make pan-scan work, you must have a pan-scan vector, a frame-based value that
controls which part of the content to use. Someone watching the video creates the vector,
deciding which parts should be seen. This vector must be available when the video is
MPEG-encoded. The MPEG encoder included with DVD Studio Pro does not support
pan-scan vector information. However, if the information is already part of an
MPEG-encoded video stream, created with an encoder that supports the vector
information, DVD Studio Pro passes this information along.
Virtually all movies shown on TV have been through the pan-scan process; however,
pan-scan vectors are rarely used for movies released on DVD. Instead, a version of the
movie is made using the 4:3 pan-scanned source and is not intended to be played as a
16:9 video on 16:9 monitors. The other side of the disc often contains the true 16:9 version,
set to display as letterboxed video on 4:3 monitors.
Important: Do not use pan-scan if your video does not actually support it. If you do, only
the center part of the frame will appear.
58 Chapter 4 Preparing Video Assets