2.5 Video Stream Types
H.264 Protocols and Communication Methods:
o Real-time Transport Protocol (RTP): RTP is a protocol that allows programs to manage the real-
time transmission of multimedia data, via unicast or multicast.
o Real Time Streaming Protocol (RTSP): RTSP serves as a control protocol to negotiate the type of
transport protocol to use for the stream. RTSP is used by a viewing client to start a unicast session.
o User Datagram Protocol (UDP): UDP is a communications protocol that offers limited service for
exchanging data in a network that uses the Internet Protocol (IP). UDP is an alternative to the
Transmission Control Protocol (TCP). The advantage of UDP is that it is not required to deliver all
data and may drop network packets when there is network congestion. This is suitable for live video
as there is no point in re-transmitting old information that will not be displayed anyway.
o Unicasting: Unicasting is communication between a single sender and a single receiver over a
network. This means that the video stream goes independently to each user and each user gets a
personal stream. A benefit of unicasting is if one stream fails it only affects one user.
o Multicasting: Multicasting is a bandwidth-conserving technology that reduces bandwidth usage by
simultaneously delivering a single stream of information to multiple network recipients. This
technology is used primarily on delimited networks (intranets) as each user needs an uninterrupted
data flow and should not rely on network routers.
2.6 How to Stream H.264
Deciding on the combination of protocols and methods to use depends on user viewing requirements a
local network properties. Setting the preferred method(s) is done on the Setup page.
o RTP+RTSP: This method (actually RTP over UDP and RTSP over TCP) should be the first
consideration for live video, especially when it is important to always have an up-to-date video
stream, even if some of the images are lost due to network problems. This can be configured as
unicast or multicast.
o RTP/RTSP/Multicasting: This provides the most efficient use of bandwidth, especially when there
are large numbers of clients connecting simultaneously. Note, however, that a multicast broadcast
cannot pass a network router unless the router is configured to allow this. For example, it is
impossible to multicast over the Internet.
o RTP/RTSP/Unicasting: This should be used for video-on-demand broadcasting so that there is no
video traffic on the network until a client connects and requests the stream. However, as more and
more unicasts clients connect, the traffic on the network will increase and may cause congestion.
Although there is a maximum of 8 unicast viewers, note that all multicast viewers combined count
as 1 unicast viewer.
o RTP/RTSP: This unicast method is RTP tunneled over RTSP. This could be used to exploit the fact
that it is relatively simple to configure firewalls to allow RTSP traffic.
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