Digital Signal Processing Reference
In-Depth Information
Figure 18.3. IP streaming technology development.
alive mechanism was introduced, where a connection could be
reused for more than one request. Using a persistent connection
reduces the latency, because the TCP connection does not need to
be to re-negotiated after the first request has been sent.
The progression of products enabling streaming video and
audio is summarized in
Figure 18.3
.
Most of the discussion to this point has been about unicasting,
or sending video from one source to one destination. However,
many applications are multicast, such as live events, broadcast
style IP TV or security system and traffic cameras.
18.8 Multicast Video
Multicast could be accomplished by running many parallel
unicasts, assuming the video server has enough aggregate
bandwidth to support many video streams in parallel. Even if the
bandwidth did exist, it would be very inefficient. Instead, multi-
tasking is primarily supported in the router. The router is required
to recognize packets being multicast, replicate them, and send to
multiple destinations or addresses. This is not to be confused
with IP broadcasting, where a single packet is sent to all devices
on the local network.
Multicasting is generally not available on the public internet
but it can be enabled on private or corporate networks. It places
