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TeRmINoLoGy
GOP : The default is 15, and if set to 15, one I-Frame will be output per 15 frames as one
I-Frame and 14 P-Frames constitute the GOP.
The lower the GOP size is, the better the quality is; however, the bit rate as well as the data
size will increase, causing a lower of the fps. GOP(Group of Pictures) is a set of video frames
for MPEG4 and H.264 format compression, indicating a collection of frames from the initial
I-Frame (key frame) to the next I-Frame. GOP consists of 2 kinds of frames: I-Frame and
P-Frame. I-Frame is the basic frame for the compression, also known as Key Frame, which
contains one complete image data. P-Frame contains only the data that has changed from
the preceding I-Frame.
Entropy coding : Data transfer technology used to reduce the compression loss from encoding.
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CAVLC (Context-adaptive variable-length coding): Records a higher compression loss
rate than CABAC.
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CABAC (Context-adaptive binary arithmetic coding): Shows a lesser compression loss than
CAVLC.
Bitrate Control
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CBR(Constant Bitrate)
This will transfer video data in an equal size at all times, regardless of the video
complexity. The video quality may be deteriorated, depending on the video complexity.
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VBR(Variable Bitrate)
The amount of video data to transfer may differ, depending on the video complexity. This
enables receiving video data in an equal quality at all times.
TTL : TTL stands for "Time To Live", which you can specify to prevent loss of data packet that
passes through multiple-staged routers. Each router decreases the TTL value by one each
time a packet passes it through; If the TTL value reaches 0, the packet cannot further pass
through a router.
TCP : It is a general purpose protocol used for transmission that requires reliability. With
constant communication between the sender and recipient, it provides high reliability against
transmission data loss; however, it has imitation to transmit a large amount of data in real time
at a high speed.
It enables reliable data transmission over xDSL and cable network at a relatively slow speed.
UDP (Unicast): It refers to a system that transmits data between only one transmitter and one
receiver (1:1).
UDP (Multicast): It refers to the data transfer protocol in one-to-many (1:N) between the trans-
mitting and receiving terminals; although it alleviates the network load, it requires <Multicast>
router.
For more information such as whether the network over which the camera is installed sup-
ports <Multicast>, contact the network administrator.
UDP : It is a protocol appropriate to transmit a large amount of data such as multimedia data at a
high speed. However, with its nonconnection structure, it records a higher transmission efficiency
than TCP especially in a high LAN environment faster than 100Mbps.
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