Image Processing Reference
Figure 2-4 PDA video player prototype. Source: courtesy of Christopher Barnatt.
a field headquarters. The problem is mainly one of picture size and available bandwidth
for delivery. Figure 2-4 shows an example design provided by Christopher Barnatt.
Online Interactive Multi-Player Games
Multi-player online gaming systems have become very popular in recent years. The real-
ism of the visuals increases all the time. So, too, does the requirement to hurl an ever-
growing quantity of bits down a very narrow pipe. The difficulty increases as the games
become more popular, with more streams having to be delivered simultaneously.
Online games differ significantly from normal video, because for a game to be com-
pelling, some aspects of what you see must be computed as a consequence of your actions.
Otherwise, the experience is not interactive enough. There are some useful techniques to
apply that will reduce the bit rate required. For example, portions of the image can be
static. Static images don't require any particular bit rate from one frame to the next since
they are unchanged. Only pixels containing a moving object need to be delivered.
More sophisticated games are evolving, and interactivity becomes more interesting
if you cache the different visual components of the scene in the local player hardware and
then composite them as needed. This allows some virtual-reality ( VR ) techniques to be
employed to animate the backdrop from a large static image.
Nevertheless, compression is still required in order to shrink these component assets
down to a reasonable size, even if they are served from a local cache or CD-ROM .
New standards-based codecs will facilitate much more sophisticated game play.
Codecs such as H.264 are very efficient. Fully exploiting the capabilities of the MPEG-4