Dataton WATCHOUT User's Guide

A 1200-by-480 movie to be presplit
across two overlapping 800 by
600 display areas.
Crop left
by 480
pixels.
Crop right
by 480
pixels.
This can all be avoided by splitting the image using the originating application,
prior to compression. Most applications allow you to crop the output to any
desired rectangle. In some cases, you can even set up batches to generate all
the individual movie files in one go.
Assuming that you have two 800 by 600 pixel displays with a 30% overlap,
and want to display a movie of 1200 by 480 pixels, the split would appear as
in the illustration to the left.
Include the overlap in the split, since the portion of the image in the overlap will
have to play on both displays. Likewise, if the displays aren’t overlapping you
will have to factor in any gap between the edges of the display areas by specifying
a corresponding gap when making the split.
Note that most applications specify cropping relative to the initial image size.
This means that the bottom and right edges need to be calculated based on the
height and width of the original (large) image.
▼ IMPORTANT: When splitting a large movie into smaller pieces like this,
avoid using a heavily compressed movie as the source. Doing so would introduce
an additional de-compression/re-compression step, resulting in
lower quality. Thus, whenever possible, start out with the original material,
such as individual, computer-generated, frame image files.
Chapter 6: Media Files 77