FLIR FC Series Installation Manual page 46

Advanced Configuration
For enhanced security, RTSP authentication can be
enabled.
By default, the video streams from the camera are sent
using unicast packets rather than multicast. This means a
given packet of IP Video will be sent separately to each
client that has that video stream open. Therefore each
additional client will cause the bandwidth to increase and
cause more overhead on the system in comparison to
multicast.
The Multicast option can be used to limit how much
bandwidth is required for multiple clients, but it requires a
higher level of network administration and an
understanding of how multicast traffic is manged (multicast
addresses, routers and switches, and so on). With
Multicast enabled, new fields are shown, Destination
Network IP address and Destination Port, as well as TTL
(time-to-live). If more than one camera is providing
multicast streams on the network, be sure to configure
each stream with a unique multicast Destination Network
IP address and Destination Port combination.
The time-to-live field controls the ability of IP packets to
traverse network or router boundaries. A value of 1 restricts
the stream to the same subnet. Values greater than 1 allow
ever increasing access between networks.
There are some challenges with streaming video over an IP network, when compared to applications
which are less time-critical, such as email and web browsing. There are requirements which must be
fulfilled to ensure satisfactory video quality in professional security environments. There are many
parameters and factors related to network infrastructure, protocols, codecs, and so on that can affect
the quality and bit rate of a video stream when it is established between the camera and a client.
The video streaming is done using a protocol generally referred to as Real-time Transport Protocol
(RTP), but there are actually many protocols involved, including Real-Time Transport Control
Protocol (RTCP) and Real Time Streaming Protocol (RTSP). In the background, a "negotiation"
takes place to establish a session between the client (such as FLIR Latitude, or a third party VMS or
video player) and the camera. The ports which form a session are negotiated using a protocol such
as RTSP. A client typically requests a video stream using its preferred settings, and the camera can
respond with its preferred settings. As a result, many of the details are established dynamically,
which may run contrary to network security requirements.
In some networks, the RTP/RTSP traffic is carried (tunneled) over Hypertext Transfer Protocol
(HTTP) as that may allow the traffic to cross network boundaries and firewalls. While this method
involves more overhead due to encapsulation, it may be necessary for clients to access the video
streams when HTTP proxies are used.
RTSP is originated and received on even port numbers and the associated RTCP communication
uses the next higher odd port number; the default RTSP Port is 554.
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