Vivotek IP8371E, Руководство пользователя

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VIVOTEK
User's Manual - 59
The frame rate will decrease if you select a higher resolution.
■ Intra frame period
Determine how often to plant an I frame. The shorter the duration, the more likely you will get
better video quality, but at the cost of higher network bandwidth consumption. Select the intra
frame period from the following durations: 1/4 second, 1/2 second, 1 second, 2 seconds, 3
seconds, and 4 seconds. The default is 1/2 second if the stream resolution is set to 1080P.
■
Video quality
• Constant bit rate: A complex scene generally produces a larger file size, meaning
that higher bandwidth will be needed for data transmission. The bandwidth
utilization is configurable to match a selected level, resulting in mutable video quality
performance. The bit rates are selectable at the following rates:
20Kbps, 30Kbps,
40Kbps, 50Kbps, 64Kbps, 128Kbps, 256Kbps, 512Kbps, 768Kbps, 1Mbps, 2Mbps, 3Mbps,
4Mbps, 6Mbps, 8Mbps, 10Mbps, 12Mbps, 14Mbps, 16Mbps, 18Mbps, 20Mbps, 24Mbps,
28Mbps, and 32Mbps
. You can also select Customize and manually enter a value.
- Target bit rate : select a bit rate from the pull-down menu. The bit rate ranges
from 20kbps to a maximum of 32Mbps. The bit rate then can be a limiting factor for
controlling the quality and the bandwidth consumed for transmitting this video stream.
This bit rate restriction method is particularly useful when planning a configuration
consisting of numerous cameras where video streams can produce high demands
both on network bandwidth and storage space. For example, storing a 6Mbps stream
for 24 hours requires a 63GB disk space. The Network Camera will strive to deliver
video streams within the bit rate limitation you impose.
- Policy: If Frame Rate Priority is selected, the Network Camera will try to maintain
the frame rate per second performance, while image quality will be compromised. If
Image quality priority is selected, the Network Camera may drop some video frames
in order to maintain image quality.
• Fixed quality: On the other hand, if Fixed quality is selected, all frames are
transmitted with the same quality; bandwidth utilization is therefore unpredictable. If
Fixed quality is selected, frame rate performance will be compromised.
- Quality: You can select the following quality options - Medium, Standard,
Good, Detailed, and Excellent. The image quality will then be determined by the
compression rate. For example, a lower quality means a higher compression rate.
The higher the compression rate, the higher the possibility of image distortion, etc.
You can also select Customize and manually enter a logical value from 0 to 51
(H.264), 2 to 31 (MPEG-4), or 2 to 97(MJPEG).
- Maximum bit rate: With the guaranteed image quality, you might still want to place
a bit rate limitation to control the size of video streams for bandwidth and storage
concerns. The configurable bit rate starts from 1Mbps to 40Mbps.
You may also manually enter a bit rate number by selecting the Customized option.