5

Field order refers to the order in which each pair of video fields is recorded. Because video
fields are recorded sequentially, it’s as if each 29.97 fps clip is really playing at 60 “frames”
per second.
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 required by your playback system.
Because motion continues from one field to the next, it’s crucial that each field plays in
the correct order.
Using Square or Nonsquare Pixels When Creating Graphics
When you’re preparing to import graphics into Motion, be aware of the pixel aspect ratio
you’re using and whether your project requires you to work with square or nonsquare
pixels.
• Use nonsquare pixels for standard-definition projects in NTSC or PAL.
• Use square pixels for full-raster high-definition projects as well as multimedia video
that will be played back only on computers and doesn’t use captured video footage.
• Use square pixels for graphics used in projects with decimated raster frame sizes, such
as DVCPRO HD formats recorded with a squeezed 1280 x 1080 frame size, but which
are later stretched during playback to 1920 x 1080. Raster decimation is a strategy for
lowering the data rate of recorded HD video; however, the final result is almost always
mastered at the nearest corresponding full-raster resolution. By creating composited
graphics and animation at the full-raster resolution used for output, you’ll simplify your
asset creation, and guarantee the highest quality.
Graphics created on a computer, whether scanned, painted, or rendered, will look distorted
on a standard-definition video display unless you account for the different pixel aspect
ratio. Fortunately, this is easy to do, because every nonsquare video frame size has an
equivalent square frame size that you can use to create your graphics.
To create graphics that look correct when output to video
1 In your graphics application, create a frame size that’s the square pixel equivalent of the
video frame size you’re using.
See the chart below for equivalent sizes. For example, if you’re working in DV-PAL with
a nonsquare video frame size of 720 x 576, your graphic should have a square pixel frame
size of 768 x 576.
1426 Appendix B Video and File Formats