8.Features
© China Daheng Group, Inc. Beijing Image Vision Technology Branch 144
Among them: the
𝑆𝑖𝑧𝑒
𝑝𝑘𝑡
is packet size,
𝐷𝑒𝑙𝑎𝑦
𝑝𝑘𝑡
is packet delay,
BandW
𝑟𝑒𝑠𝑒𝑟𝑣𝑒
is reserved bandwidth,
𝑆𝑝𝑒𝑒𝑑
𝑙𝑖𝑛𝑘
is link speed.
Effective network bandwidth:
Band𝑊
𝑎𝑣𝑖𝑎𝑙
= (𝑆𝑖𝑧𝑒
𝑝𝑘𝑡
× 8𝑏𝑖𝑡𝑠 × (1 − Band𝑊
𝑟𝑒𝑠𝑒𝑟𝑣𝑒
)/(𝑇
𝑑𝑎𝑡𝑎
+ 𝑇
𝑑𝑒𝑙𝑎𝑦
)
Example 1
: The packet size is 1500, the packet delay is 1000, the reserved bandwidth is 20%, and the
link speed is 1Gbps.
The time to transport a single stream packet is:
𝑇
𝑑𝑎𝑡𝑎
= (1500 × 8) 1000,000,000
⁄
= 12𝑢𝑠
The time of packet delay is:
𝑇
𝑑𝑒𝑙𝑎𝑦
= 1000 125,000,000
⁄
= 8𝑢𝑠
The effective network bandwidth is:
Band𝑊
𝑎𝑣𝑖𝑎𝑙
= (1464 × 8 × (1 − 0.2))/(12𝑢𝑠 + 8𝑢𝑠) = 468𝑀𝑏𝑝𝑠
Note: Each stream packet contains 36 bytes of network header data, and a packet with the size of 1500
bytes contains only 1464 bytes of valid data.
Example 2
: The packet size is 8192, the packet delay is 2000, the reserved bandwidth is 20%, and the
link speed is 1Gbps.
The time to transport a single stream packet is:
𝑇
𝑑𝑎𝑡𝑎
= (8192 × 8) 1000,000,000
⁄
= 66𝑢𝑠
The time of packet delay is:
𝑇
𝑑𝑒𝑙𝑎𝑦
= 2000 125,000,000
⁄
= 16𝑢𝑠
The effective network bandwidth is:
Band𝑊
𝑎𝑣𝑖𝑎𝑙
= (8156 × 8 × (1 − 0.2))/(66𝑢𝑠 + 16𝑢𝑠) = 637𝑀𝑏𝑝𝑠
8.5.4. Bandwidth Reserve
The Bandwidth Reserve is used to reserve a part of bandwidth for packet retransmission and control data
transfer between the camera and the host, and can be used for multiple cameras transmission, to limit the
bandwidth allocation of each camera. For example, the network bandwidth is 1Gbps, setting the reserved
bandwidth value to 20%, then the bandwidth will be reserved to 0.2Gbps. When the maximum bandwidth
required for transmission is greater than the current bandwidth available, the camera reduces the frame
rate to ensure the stability of the transmission.
