Apple Motion 3 - Manual (Page 1212)

1212 Appendix B Video and File Formats
JPEG
JPEG is similar to M-JPEG, except that the compression artifacts can be less severe at
similar data rates. JPEG movies may play back in real time on your system, depending
on your system’s speed and the data rate of the movie.
Note: JPEG movies cannot have alpha channels.
Third-Party Codecs
There are several manufacturers of video-editing solutions, most of whom use different
variations of the M-JPEG codec. Many make software-only QuickTime codecs that you
can install in your System folder, enabling you to play back movies with little or no
rerendering. For more information, contact the manufacturer of the editing system.
Note: Most third-party codecs cannot have alpha channels.
What Is Field Order?
All video displays, whether analog or digital, work by breaking a single frame of video
into individual lines of horizontal resolution running across the screen. Standard
definition NTSC and PAL are both interlaced video formats, as opposed to high
definition video, or video displayed on a computer screen, which are progressive-
scanned video formats. With progressive scanning, these lines are drawn one at a time,
from the top of the screen to the bottom.
Interlaced video, including NTSC and PAL, works differently. When you record footage
with your camcorder, each video frame is broken down into two fields, each containing
half of the total lines of resolution in the frame. The first field is recorded, then the
second, and both are laid down to tape, one after the other, so that both fields
constitute one frame. When you play the tape back, a television monitor displays each
recorded frame in two passes, first drawing field 1, then drawing field 2.
Field order refers to the order in which video fields are recorded from your video
equipment to your hard disk. If you remember that video fields come one after another
in time, as if playing 60 “frames” per second, it becomes a little easier to understand.
There are two options for field order:
 Upper (Field 2 is dominant, so the second field is drawn first.)
 Lower (Field 1 is dominant, so the first field is drawn first.)
Generally, Upper is used by 640 x 480 systems, while Lower is most common in
professional 720 x 486 and DV 720 x 480 systems.
It’s important to render digital video with the field order used by your hardware.
Because motion continues from one field to the next, it’s crucial that each field plays in
the correct order. Because different capture cards handle interlacing differently,
choosing the correct field order ensures proper playback.