Dataton WATCHOUT User's Guide

Pre-splitting Large Movies
In order to play a movie that’s larger than a single display, the movie must be
split into multiple movies, one for each display. A single display computer is
generally not capable of playing back a movie that’s larger than its display
size, even though some of the image would fall outside the visible display area.
While this function is built into WATCHOUT for still images, it is not handled
automatically for moving images. The primary reason for this difference is that
the original, large-size movie would most likely have to be compressed in
order to be stored and distributed to the display computers. These could then
handle the splitting, as they do for still images. In doing so, they would have to
decompress each frame, split it and then re-compress the result again for final
playback. This would mean that each movie frame will be compressed twice,
most likely using lossy compression in both cases. The end result would be a
loss of image quality.
In addition to this quality aspect, there are also storage and bandwidth considerations
related to distributing and storing the original (large) movie in order
to split it, as well as the processing time involved in compressing it twice. The
latter would be significant for such a large movie, particularly to achieve the
best quality).
76 Chapter 6: Media Files