Data Transport Methods

Source (video) data from a VNC 325 encoder can be distributed to multiple decoders and
displays (one-to-many) or to a single decoder and display (point-to-point). Video data is
transported from the source (encoder) to the display (decoder) using one of three methods,
in order of preference, which are detailed in the following sections:
• Multicast real-time protocol (RTP) — Best choice
• Unicast RTP — Second choice
• Unicast Transport Control Protocol (TCP) — Acceptable
You need to select among these three methods using the HTML pages, see “Configure
Encoders or Decoders“ on page 25.

Multicast RTP

The multicast real-time protocol (RTP) data transport method is connected as shown in
figure 3. Multicast RTP is a one-to-many protocol that allows a source to be displayed on
an infinite number of displays. This transport method uses a real-time variation of User
Datagram Protocol (UDP), called RTP. In figure 3, the streaming data is identified as “RTPm”.
System Control
System Control
Network
Netw
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Monitoring and
Control
IP Encoder IP Decoder 2
IP Decoder 1
IP Decoder 3
IP Decoder 4
IP Decoder n-1
IP Decoder n
Any number of decoders can
be part of the multicast RTP group.
RTPm
Program Data
RTPm
Program Data
RTPm
Program Data
RTPm
Program Data
RTPm
Program Data
Decoder Configured as Controller
Figure 3. Typical Multicast RTP Application
NOTES: • The UDP protocol is a standard Internet network protocol that is connection-
less, meaning that it does not use the hand-shaking that provide reliability,
ordering, or data integrity but is overhead intensive. Therefore, UDP can
be unreliable. On the other hand, RTP provides very low latency, which is
important for video transport.
• The VN-Matrix 325 supports IGMP V2 for multicast streaming.
VN-Matrix 325 Serial Digital Over IP CODEC • Installation and Setup 8