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.

-CAVLC (Context-adaptive variable-length coding): Records a higher compression loss rate than CABAC.

-CABAC (Context-adaptive binary arithmetic coding): Shows a lesser compression loss than

CAVLC.

￿Bitrate Control

-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.

-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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