427-9030-01-12 Version 140
March 2018
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2
Basic Operation and Configuration
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.
By default, the video streams from the camera are sent using
multicast packets. With Multicast enabled, video packets are
shared by streaming clients, so additional clients do not cause
bandwidth to increase as dramatically.
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 boundaries. A value of 1 restricts the stream
to the same subnet. Greater values allow increasing access
between networks.
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, 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.
The parameters in the Settings section will have a
significant impact on the quality and bandwidth
requirements of the video stream. In general it is
recommended that the default values be used initially. Then
individual parameters can be modified and tested
incrementally to determine if the bandwidth and quality
requirements are met.
For video streams, the Codec options are H.264, MJPEG
and MPEG4.
The Bit Rate parameter is used with the CBR (Constant Bit
Rate) setting to attempt to keep the resulting bit rate of the
video at or near the target bit rate.
When the Rate Control parameter is set to CVBR
(Constrained Variable Bit Rate), the Bit Rate parameter is
used as an upper limit bit rate and the system keeps the
stream at or under the target bit rate.
The I-Frame Interval parameter controls the number of P-frames used between I-frames. I-frames are
full frames of video and the P-frames contain the changes that occurred since the last I-frame. A
smaller I-Frame Interval results in higher bandwidth (more full frames sent) and better video quality. A
higher I-Frame Interval number means fewer I-frames are sent and therefore results in lower
bandwidth and possibly lower quality.
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